JP7395873B2 - Gear cutting tool grinding method, grinding device, grinding wheel shape and grinding condition determining device - Google Patents

Description

The present invention relates to a method for grinding a gear cutting tool, a grinding device, and a device for determining grinding wheel shape and grinding conditions.

A gear cutting tool for cutting a gear is formed into a shape based on the shape of the gear to be cut. When the cutting edge surface of the gear cutting tool is worn out, regrinding (regrinding) is performed to reshape the blade (see Patent Document 1). Incidentally, in recent years, there has been a demand for gear machining that allows high-speed cutting from a cost perspective, and skiving machining is known. Patent Document 2 describes that in a gear cutting tool (skiving cutter) for skiving processing, the left and right blade side surfaces and the tooth tip surface are simultaneously ground by one grinding wheel.

Patent No. 4763611 JP 2017-226019 Publication

Here, some gear cutting tools are provided with a front relief angle and a side relief angle. The front clearance angle is the clearance angle on the cutting edge surface of the gear cutting tool. The side clearance angle is the clearance angle on the side surface of the blade of the gear cutting tool. Further, the gear cutting tool is designed based on the front relief angle, side relief angle, pressure angle perpendicular to the blade, rake angle, and helix angle on the reference circle.

To resharpen the gear cutting tool used in skiving, each blade is reshaped by grinding the axial end face (rake face) of the gear cutting tool. The relationship between the front clearance angle Φ and the side clearance angle ε of the gear cutting tool becomes a parameter that determines the amount by which the blade of the gear cutting tool can be resharpened.

In order to extend the life of a gear cutting tool, it is necessary to secure a large amount of resharpening of the blade of the gear cutting tool. In addition, in order to improve grinding efficiency, it is required to grind opposing blade sides (left and right blade sides) using one grinding wheel.

The present invention provides a method for grinding a gear cutting tool that allows a large amount of re-sharpening to be achieved by simultaneously grinding opposing blade sides using a single grinding wheel, and a device for determining the shape of the grinding wheel and grinding conditions. It is to provide.

(1. Grinding method of gear cutting tool)
A method for grinding a gear cutting tool according to the present invention is a method of simultaneously grinding opposing blade sides of a gear cutting tool used for skiving using a grinding wheel formed in a disc shape, the method comprising: Based on the amount of re-sharpening and the shape error of the gear machined by the gear cutting tool, the target of the gear cutting tool is different from the reference front clearance angle and reference side clearance angle as the standard specifications of the gear cutting tool. A target specification determining step of determining a target front relief angle and a target side relief angle as specifications, and a step of determining a front relief angle and a side relief angle as manufacturing specifications of the gear cutting tool. a manufacturing specification determining step of determining the manufacturing specifications of the gear cutting tool, and determining the shape and shape of the grinding wheel based on the manufacturing specifications of the gear cutting tool in order to keep the clearance angle within the allowable value; The method includes a shape and condition determining step of determining grinding conditions, and a grinding step of grinding the gear cutting tool using the grinding wheel according to the grinding conditions.

(2. Grinding device for gear cutting tools)
A grinding device for a gear cutting tool according to the present invention is a grinding device for simultaneously grinding opposing blade sides of a gear cutting tool used for skiving processing using a grinding wheel formed in a disc shape. Based on the re-sharpening amount of a target specification determination unit that determines a target front clearance angle and a target side clearance angle as target specifications; and a target specification determination unit that determines a front clearance angle and a side clearance angle as manufacturing specifications of the gear cutting tool, and a target front clearance angle and a target side clearance angle as manufacturing specifications of the gear cutting tool. a manufacturing specification determination unit that determines the manufacturing specifications of the gear cutting tool, and a shape of the grinding wheel based on the manufacturing specifications of the gear cutting tool, in order to make the side clearance angle within the allowable value; and a shape and condition determining unit that determines grinding conditions, and a grinding unit that uses the grinding wheel to grind the gear cutting tool according to the grinding conditions.

(3. Grinding wheel shape and grinding condition determining device)
The grinding wheel shape and grinding condition determining device according to the present invention provides a grinding method for simultaneously grinding opposing blade sides of a gear cutting tool used for skiving using a grinding wheel formed in a disk shape. A grinding wheel shape and grinding condition determination device that determines the shape and grinding conditions of a grinding wheel, the grinding wheel shape and grinding conditions determining device determining the shape and grinding conditions of the gear cutting tool based on the amount of re-sharpening of the gear cutting tool and the shape error of the gear machined by the gear cutting tool. a target specification determining unit that determines a target front relief angle and a target side relief angle as target specifications of the gear cutting tool that are different from a reference front relief angle and a reference side relief angle as reference specifications; Manufacturing specifications for determining the manufacturing specifications of the gear cutting tool so that the front clearance angle and side clearance angle as manufacturing specifications of the tool are within tolerance values from the target front clearance angle and the target side clearance angle. and a shape and condition determining unit that determines the shape and grinding conditions of the grinding wheel based on the manufacturing specifications of the gear cutting tool.

According to the gear cutting tool grinding method, grinding device, and grinding wheel shape and grinding condition determining device according to the present invention, a target front relief angle and a target side relief angle that allow a large amount of re-grinding are determined, and the determined target The manufacturing specifications of the gear cutting tool are determined based on the front clearance angle and the target side clearance angle. As a result, a skiving gear cutting tool can be obtained that allows for a large amount of re-sharpening and can simultaneously grind at least the opposing blade sides with one grinding wheel. Therefore, the total cost of gear cutting tools can be reduced at sites where gears are mass-produced.

It is a diagram of a grinding device (grinding machine) that uses a gear cutting tool as an object to be ground and includes a grinding wheel. FIG. 1A is a diagram seen from the IB direction in FIG. 1A. It is a gear cutting tool for cutting gears, and is a view of the gear cutting tool as an object to be ground, viewed from a direction perpendicular to the central axis. FIG. 2B is a cross-sectional view of the gear cutting tool of FIG. 2A viewed from the central axis direction. FIG. 2 is a perspective view of a grinding wheel for grinding a gear cutting tool. FIG. 3B is a cross-sectional view of the outer peripheral edge of the grinding wheel shown in FIG. 3A when viewed from a direction perpendicular to the central axis. FIG. 2 is a diagram of a gear to be cut, viewed from a direction perpendicular to the central axis. It is a figure showing the relationship between standard specifications and target specifications of a gear cutting tool. It is a figure which shows the relationship between the gear tooth thickness error and the resharpening amount of a gear cutting tool when a front relief angle and a side relief angle are changed. It is a figure which shows the relationship of the target specification of a gear cutting tool, a calculation auxiliary value, and a first example of manufacturing specification. It is a figure which shows the relationship of the target specification of a gear cutting tool, a calculation auxiliary value, and a second example of manufacturing specification. FIG. 3 is a diagram showing a processing device of a gear cutting tool grinding device. It is a flow chart for explaining a gear cutting tool grinding method. It is a first flowchart for explaining a method for determining manufacturing specifications of a gear cutting tool. It is a second flowchart for explaining the determination method of manufacturing specifications of a gear cutting tool.

(1. Configuration of gear cutting tool grinding device 20)
The gear cutting tool grinding device 20 will be described with reference to FIGS. 1A and 1B. This gear cutting tool grinding device 20 uses a grinding wheel 3 to grind at least the opposing blade side surface 2d (see FIG. 2A) of the blade 2a of the gear cutting tool 2 for cutting the gear 1 (see FIG. 4). Further, the gear cutting tool grinding device 20 may also grind the cutting edge surface 2c of the gear cutting tool 2 at the same time using the grinding wheel 3. The gear cutting tool grinding device 20 is, for example, a tool grinder or an angular grinder.

The gear cutting tool grinding device 20 includes a main shaft unit 21 that rotatably supports the gear cutting tool 2, which is the object of grinding, around the central axis X2 (θ22) of the gear cutting tool 2 on a bed (not shown). Furthermore, the gear cutting tool grinding device 20 includes a grindstone head 22 that supports the grinding wheel 3 rotatably around the central axis X3 (θ3) of the grinding wheel 3.

The spindle unit 21 and the grindstone head 22 are provided so that their positions and postures can be changed relative to each other. That is, the gear cutting tool grinding device 20 includes a drive device (not shown) for relatively changing the position and orientation of the spindle unit 21 and the grindstone head 22.

In detail, as shown in FIGS. 1A and 1B, the grindstone head 22 can adjust the intersection angle η in grinding the gear cutting tool with respect to the main spindle unit 21 (parallel line between the central axis X2 of the gear cutting tool 2 and the grinding wheel It is possible to adjust the angle of inclination by an intersection angle η from a state in which the center axis X3 of the vehicle 3 is orthogonal to the center axis X3 of the vehicle 3. Further, the grindstone head 22 is movable relative to the spindle unit 21 in three orthogonal axes directions. The intersection angle η between the grindstone head 22 and the spindle unit 21 is adjusted according to the helix angle β (shown in FIG. 2A) of the gear cutting tool 2. Note that the spindle unit 21 and the grindstone head 22 only have to move relative to each other, and the spindle unit 21 may be configured to be movable.

The gear cutting tool grinding device 20 further includes a processing device 40. The processing device 40 determines target specifications of the gear cutting tool 2 based on the reference specifications of the gear cutting tool 2, and determines manufacturing specifications of the gear cutting tool 2 based on the determined target specifications. Then, the processing device 40 determines the shape and grinding conditions of the grinding wheel 3 based on the determined manufacturing specifications of the gear cutting tool 2, and grinds the gear cutting tool 2 with the grinding wheel 3 based on the determined grinding conditions. do. Note that reference specifications, target specifications, and manufacturing specifications regarding the gear cutting tool 2 will be described later.

Further, in grinding the gear cutting tool 2, the processing device 40 controls the rotation of the gear cutting tool 2, the rotation of the grinding wheel 3, and the relative position and orientation of the spindle unit 21 and the grinding wheel head 22. The processing device 40 may be an embedded system such as a CNC (Computer Numerical Control) device or a PLC (Programmable Logic Controller), or may be a personal computer, a server, or the like.

(2. Shape of gear cutting tool 2)
The outline of the shape of the gear cutting tool 2 will be described with reference to FIGS. 2A and 2B. As shown in FIGS. 2A and 2B, the shape of the gear cutting tool 2 includes a plurality of blades 2a on the outer peripheral surface around the central axis X2. The gear cutting tool 2 includes a rake face 2b having a rake angle γ on the end face in the axial direction. The rake face 2b may be tapered around the central axis X2 of the gear cutting tool 2, or may be formed into a plane facing in a different direction for each blade 2a.

Moreover, the circumscribed circle of the plurality of blades 2a of the gear cutting tool 2 is formed in the shape of a truncated cone. That is, the cutting edge surfaces 2c of the plurality of blades 2a serve as front clearance surfaces having a front clearance angle Φ with respect to the rake surface 2b. Therefore, the distance from the central axis X2 of the gear cutting tool 2 at the cutting edge surface 2c gradually decreases as one goes from one end surface of the blade 2a to the blade line direction (equal to the blade groove direction). Further, the plurality of blades 2a have a pressure angle α between the tangent Lt of the blade side surface 2d and the radius line Lr perpendicular to the central axis X2 at the intersection of the blade side surface 2d and the reference circle C, that is, the pitch point P. ing.

Further, the blade side surfaces 2d of the plurality of blades 2a serve as side relief surfaces having a side relief angle ε with respect to the rake surface 2b. Furthermore, the plurality of blades 2a have a twist angle β with respect to the central axis X2. However, the helix angle β of the blade 2a varies as appropriate depending on the helix angle of the teeth 1a of the gear 1 and the intersection angle between the gear 1 and the gear cutting tool 2 during cutting. Therefore, there are cases where the blade 2a does not have the helix angle β.

(3. Outline of shape of grinding wheel 3)
The outline of the shape of the grinding wheel 3 will be explained with reference to FIGS. 3A and 3B. As shown in FIG. 3A, the grinding wheel 3 mainly grinds the opposing blade side surface 2d of the blade 2a of the gear cutting tool 2, with the gear cutting tool 2 as a grinding target. The grinding wheel 3 is formed into a disk shape around a central axis X3. As shown in FIG. 3B, the outer peripheral edge 3a of the grinding wheel 3 has a shape that corresponds to the shape of the blade groove of the gear cutting tool 2 so that the opposing blade sides 2d of the blade 2a of the gear cutting tool 2 can be simultaneously ground. is formed. Further, by adding step portions 3b to both end surfaces of the outer peripheral edge portion 3a of the grinding wheel 3, it is possible to simultaneously grind the opposing blade side surface 2d and the blade edge surface 2c.

(4. Shape of gear 1)
The outline of the shape of the gear 1 will be explained with reference to FIG. 4. As shown in FIG. 4, the shape of the gear 1 to be cut by the gear cutting tool 2 includes a plurality of teeth 1a on the circumferential surface around the central axis X1. In this embodiment, the gear 1 is an external gear, but an internal gear can also be applied. Further, in FIG. 4, the gear 1 is a spur gear, but various gears such as a helical gear can be used.

(5. Grinding method)
Grinding of the gear cutting tool 2 is performed as follows. First, the gear cutting tool 2 is positioned such that a parallel line between the central axis X2 and the central axis X3 of the grinding wheel 3 have an intersection angle η. At this time, the disc of the grinding wheel 3 is in a state where it almost coincides with the direction of the blade groove of the gear cutting tool 2. That is, the grinding wheel 3 is positioned between the adjacent blades 2 of the gear cutting tool 2, that is, in the blade groove. The helix angle β of the gear cutting tool 2 and the intersection angle η between the gear cutting tool 2 and the grinding wheel 3 are substantially the same. However, in this example, as will be described later, the helix angle as a reference specification (design specification) of the gear cutting tool 2 and the intersection angle η between the gear cutting tool 2 and the grinding wheel 3 are different.

In this state, the gear cutting tool 2 is rotated around its central axis X2, the grinding wheel 3 is rotated around its central axis X3, and the movement of the grinding wheel 3 is synchronized with the rotation of the gear cutting tool 2. In the synchronous operation, the grinding wheel 3 is relatively moved in the axial direction of the gear cutting tool 2 so as to match the blade groove of the gear cutting tool 2, and the grinding wheel 3 is also relatively moved in the radial direction of the gear cutting tool 2. The amount of movement in the radial direction corresponds to the front clearance angle of the gear cutting tool 2. In this way, the gear cutting tool 2 is ground by the grinding wheel 3.

(6. Standard specifications and target specifications of gear cutting tool 2)
The standard specifications and target specifications of the gear cutting tool 2 will be explained with reference to FIGS. 5 and 6. As shown in FIG. 5, the standard specifications of the gear cutting tool 2 include the module m, the pressure angles α _L and α _R of the left and right blade sides 2d, the number of teeth Z, the helix angle β, the standard circle diameter D, and the outer diameter Da. , the blade bottom circle diameter Df, the front clearance angle Φ (reference front clearance angle), the side clearance angle ε (reference side clearance angle), and the rake angle γ are set. Among the standard specifications of the gear cutting tool 2, the module m, the pressure angles α _L and α _R of the left and right blade sides 2d, the number of teeth Z, the helix angle β, the standard circle diameter D, the outer diameter Da, and the blade bottom circle diameter Df. , the rake angle γ are determined based on the specifications of the gear 1 to be machined by the gear cutting tool 2. Here, since the pressure angle α of the left and right blade side surfaces 2d is different, the pressure angle α L of the left blade side surface 2d is taken as the pressure angle α _L , and the pressure angle α _{R of the right blade side surface 2d is taken as the pressure angle α R.}

Among the standard specifications of the gear cutting tool 2, the front clearance angle Φ and the side clearance angle ε are determined based on the relationship of equation (1). Note that in equation (1), α indicates a pressure angle, and, for example, approximate values of the left and right pressure angles α _L and α _R are used.

When the gear cutting tool 2 is ground by the grinding wheel 3 so that the front clearance angle Φ and the side clearance angle ε obtained from equation (1) are obtained, the re-grinding amount of the gear cutting tool 2 and the tooth thickness of the gear 1 are The relationship with the error is as shown by the broken line A in FIG. Re-sharpening of the gear cutting tool 2 is a process of reshaping each blade 2a by grinding the rake face 2b located on the axial end face of the gear cutting tool 2. As shown by the broken line A in FIG. 6, the more the gear cutting tool 2 is resharpened, the larger the tooth thickness error of the gear 1 becomes. In the range where the tooth thickness error of the gear 1 is included in the tolerance shown by the two-dot chain line in FIG. 6, the re-sharpening amount for the basic gear cutting tool 2 described above is Ta.

Therefore, the inventors considered setting specifications different from the standard specifications of the gear cutting tool 2 as described above, and determined target specifications of the gear cutting tool 2 that can increase the amount of resharpening. did. Here, since the relationship between the front clearance angle Φ and the side clearance angle ε of the gear cutting tool 2 is a parameter that determines the amount that the gear cutting tool 2 can be resharpened, the target specifications of the gear cutting tool 2 are as follows: The front clearance angle Φ ₀ and the target side clearance angle ε ₀ were determined. The target front clearance angle Φ ₀ and the target side clearance angle ε ₀ are different values from the front clearance angle Φ and the side clearance angle ε in the standard specifications of the gear cutting tool 2. Therefore, the target specifications of the gear cutting tool 2 do not satisfy the relationship of equation (1).

When the gear cutting tool 2 is ground by the grinding wheel 3 so that the gear cutting tool 2 has the target specifications, the relationship between the re-grinding amount of the gear cutting tool 2 and the tooth thickness error of the gear 1 is shown in FIG. This is shown by solid line B. When the gear cutting tool 2 is resharpened, the tooth thickness error increases in the opposite direction (in the upper side of FIG. 6, in the positive direction) than in the case of the standard specifications of the gear cutting tool 2. However, when the amount of re-sharpening is further increased after that, the tooth thickness error becomes smaller once and then gradually becomes larger. In other words, the target specifications of the gear cutting tool 2 are such that the tooth thickness error (shape error) of the first tooth wheel machined by the gear cutting tool 2 with respect to the resharpening amount of the gear cutting tool 2 is an extreme value within a predetermined tolerance. The specifications are as follows.

In a range where the tooth thickness error of the gear 1 is included in the tolerance shown by the two-dot chain line in FIG. 6, the re-sharpening amount for the gear cutting tool 2 having the target specifications is Tb. The regrinding amount Tb is a much larger value than the regrinding amount Ta of the gear cutting tool 2 having the above-mentioned standard specifications. In other words, it can be said that the gear cutting tool 2 having the target specifications is a tool that can undergo a large amount of resharpening.

(7. Problems in grinding gear cutting tool 2 with target specifications)
When grinding the gear cutting tool 2 with the grinding wheel 3, among the specifications of the gear cutting tool 2, the pressure angles α _L and α _R of the left and right blade sides 2d, the number of teeth Z, the helix angle β, the reference circle diameter D, The shape of the grinding wheel 3 is formed so that the rake angle γ is obtained, and the relative posture between the grinding wheel 3 and the gear cutting tool 2 is determined. The gear cutting tool 2 is then ground by moving the grinding wheel 3 with respect to the gear cutting tool 2 along the target front relief angle Φ.

Here, in the gear cutting tool 2 having the standard specifications satisfying the above-mentioned formula (1), by moving the grinding wheel 3 along the front clearance angle Φ with respect to the gear cutting tool 2, the The desired side clearance angle ε can be obtained. However, when the grinding wheel 3 is moved along the front relief angle Φ ₀ with respect to the gear cutting tool 2 in the gear cutting tool 2 having target specifications that do not satisfy formula (1), the obtained As for the side clearance angle, the desired target side clearance angle ε ₀ cannot be obtained. In other words, the grinding conditions cannot be determined based on the target specifications of the gear cutting tool 2 itself.

Therefore, by separately grinding the left and right blade side surfaces 2d of the gear cutting tool 2 having the target specifications, the desired target side relief angle ε ₀ can be obtained. However, if the left and right blade sides 2d are respectively ground by separate grinding wheels 3, the grinding efficiency will be significantly reduced. Therefore, it is required to be able to simultaneously grind the left and right blade side surfaces 2d using one grinding wheel 3, and to obtain the target side clearance angle ε ₀ of the gear cutting tool 2 having the target specifications.

In order to solve these problems, specifications of the gear cutting tool 2 in manufacturing (hereinafter referred to as manufacturing specifications of the gear cutting tool 2) are separately set based on the target specifications of the gear cutting tool 2. . Here, the manufacturing specifications of the gear cutting tool 2 are made to satisfy formula (1). Then, based on the manufacturing specifications of the gear cutting tool 2, the shape and grinding conditions of the grinding wheel 3 are determined. By doing so, it becomes possible to obtain a gear cutting tool 2 having target specifications using one grinding wheel 3.

(8. Target specifications and manufacturing specifications of gear cutting tool 2)
The relationship between target specifications and manufacturing specifications of the gear cutting tool 2 will be explained with reference to FIGS. 7 and 8. Note that FIG. 7 shows a first example of manufacturing specifications, and FIG. 8 shows a second example of manufacturing specifications.

The target specifications of the gear cutting tool 2 are, as shown in the left column of FIGS. 7 and 8, the module m, the pressure angles α _L and α _R of the left and right blade sides 2d, the number of teeth Z, the helix angle β, and the reference circle. The diameter D, target front clearance angle Φ ₀ , target side clearance angle ε ₀ , and rake angle γ are set. Here, since the pressure angle α of the left and right blade side surfaces 2d is different, the pressure angle α L of the left blade side surface 2d is taken as the pressure angle α _L , and the pressure angle α _{R of the right blade side surface 2d is taken as the pressure angle α R.}

Next, approximate values for the long-life gear cutting tool 2 shown in the center column of FIGS. 7 and 8 are determined. Here, it is assumed that the tooth surface of the gear 1 to be processed by the gear cutting tool 2 has an involute shape. Therefore, assuming that the blade side surface 2d of the gear cutting tool 2 has an involute shape (assuming that the tooth profile of the axis-perpendicular cross section of the gear cutting tool 2 is an involute tooth profile), the blade shape of the gear cutting tool 2 is defined. The lead L determined from the basic circle diameter Db and the helix angle β of the blade 2a is determined as an approximate value. The basic circle diameter Db and the lead L are used as calculation auxiliary values.

The basic circle diameter Db is obtained by D·cos α using the standard circle diameter D and the pressure angle α. Here, as mentioned above, since the blade side surface 2d of the gear cutting tool 2 for skiving processing is different on the left and right sides, the left and right pressure angles α _L and α _R are set in the target specifications of the gear cutting tool 2. ing. Therefore, in this example, the pressure angle approximation value α ₀ is determined from the two pressure angles α _L and α _R , and the basic circle diameter Db is expressed by the reference circle diameter D and the pressure angle approximation value α ₀ . The pressure angle approximation value α ₀ as a calculation auxiliary value is obtained, for example, from equation (2). Note that the pressure angle approximate value α ₀ may be the average value of the left and right pressure angles α _L and α _R , as shown in equation (3).

Next, the manufacturing specifications of the gear cutting tool 2 are determined (right column in FIGS. 7 and 8). As shown in the right column of Fig. 7, the manufacturing specifications of the first example include the approximate pressure angle α1, the number of teeth Z, the helix angle β1, the rolling circle diameter D1 (corresponding to the reference circle diameter), and the front clearance angle. Φ ₀ , side relief angle ε1, rake angle γ, base circle diameter Db, and lead L are included.

Here, as shown in the right column of FIG. 7, in the manufacturing specifications of the first example, the number of teeth Z, front clearance angle Φ ₀ , and rake angle γ are the same values as the target specifications of the gear cutting tool 2. Therefore, they are represented by the same symbols. On the other hand, in the manufacturing specifications of the first example, the pressure angle approximate value α1, helix angle β1, rolling circle diameter D1 (corresponding to the reference circle diameter), and side clearance angle ε1 are different from the design specifications or calculation auxiliary values. It is a value. Further, in the manufacturing specifications of the first example, the basic circle diameter Db and the lead L are the same values as the calculation auxiliary value.

In addition, as shown in the right column of FIG. 8, in the manufacturing specifications of the second example, the number of teeth Z, side clearance angle ε ₀ , rake angle γ, base circle diameter Db, and lead L are the target of the gear cutting tool 2. Since it is the same value as the specifications, it is represented by the same code. On the other hand, in the manufacturing specifications of the second example, the pressure angle approximate value α1, helix angle β1, rolling circle diameter D1 (corresponding to the reference circle diameter), and front relief angle Φ1 are different from the target specifications or calculation auxiliary values. It is a value. Furthermore, in the manufacturing specifications of the second example, the basic circle diameter Db and the lead L are the same values as the calculation auxiliary value. Note that the front clearance angle Φ1 and the side clearance angle ε1 in the manufacturing specifications can also be set to values different from the target specifications.

Next, a method for determining the pressure angle approximate value α1, torsion angle β1, rolling circle diameter D1, and side relief angle ε1 (or front relief angle Φ1) in the manufacturing specifications will be explained. The basic circle diameter Db can be expressed by Equation (4) using the reference circle diameter D and the pressure angle approximate value α ₀ determined by Equation (2) or Equation (3). Furthermore, in this example, since the basic circle diameter Db is the same value in the manufacturing specifications as the value obtained as the calculation auxiliary value, it can be expressed by equation (4) using the rolling circle diameter D1 and the pressure angle approximation value α1. can.

Then, by modifying the equation (4), the approximate pressure angle value α1 can be expressed by the equation (5) using the approximate pressure angle value α ₀ and the rolling circle diameter D1. Further, the twist angle β1 can be expressed by equation (6) using the lead L and the rolling circle diameter D1.

Then, the reference circle diameter D expressed by formula (7) obtained by transforming formula (4) is substituted into formulas (5) and (6) as the initial value of rolling circle diameter D1, and the pressure angle Find the approximate value α1 and twist angle β1. In the manufacturing specifications shown in FIG. 7, the obtained pressure angle approximate value α1 and torsion angle β1 are substituted into equation (8) to obtain the side clearance angle ε1. Then, the above process is repeated one by one while changing the rolling circle diameter D1 until the obtained side clearance angle ε1 falls within a predetermined tolerance value from the target side clearance angle ε ₀ . Note that this sequential processing is performed using, for example, the general Newton method.

Then, when the side clearance angle ε1 falls within a predetermined tolerance value from the target side clearance angle _ε0 , the manufacturing specifications at that point are determined. Then, the gear cutting tool 2 is ground using the grinding wheel 3 based on the obtained manufacturing specifications. The shape of the grinding wheel 3 is determined from the generation diagram using the number of blades Z, front clearance angle Φ ₀ , rake angle γ, helix angle β1, and rolling circle diameter D1.

Further, in the manufacturing specifications shown in FIG. 8, the pressure angle approximation value α1 and torsion angle β1 obtained are substituted into equation (9) to obtain the front clearance angle Φ1. Then, the above process is repeated one after another while changing the rolling circle diameter D1 until the obtained front clearance angle Φ1 falls within a predetermined tolerance value from the target front clearance angle Φ ₀ . Note that this sequential processing is performed using, for example, the general Newton method.

(9. Processing device 40 of gear cutting tool grinding device 20)
The processing device 40 of the gear cutting tool grinding device 20 will be explained with reference to FIGS. 9-12. As shown in FIG. 9, the processing device 40 includes a reference specification storage section 41, a target specification determination section 42, a calculation auxiliary value calculation section 43, a manufacturing specification determination section 44, and a grinding wheel shape and grinding condition determination section 45. , and a grinding section 46.

Here, the reference specification storage section 41, the target specification determination section 42, the calculation auxiliary value calculation section 43, the manufacturing specification determination section 44, and the grinding wheel shape and grinding condition determination section 45 are configured to It functions as a condition determining device 40a. Further, the reference specification storage section 41, the target specification determination section 42, the calculation auxiliary value calculation section 43, and the manufacturing specification determination section 44 function as a manufacturing specification determination processing device 40b.

Processing by the processing device 40 of the gear cutting tool grinding device 20 (method for grinding the gear cutting tool 2) will be described with reference to FIG. 10. The standard specification storage unit 41 stores standard specifications of the gear cutting tool 2 determined based on the gear specifications of the gear 1 to be machined. Specifically, the standard specification storage section 41 stores table data of standard specifications of the gear cutting tool 2 shown in the left column of FIG.

The target specification determining unit 42 acquires the standard specifications of the gear cutting tool 2 (step S111). The target specification determining unit 42 determines target specifications of the gear cutting tool 2 based on the standard specifications of the gear cutting tool 2 and the amount of resharpening of the blade 2a of the gear cutting tool 2 (step S112, target specifications decision process). Specifically, the target specifications determination unit 42 determines the target specifications shown in the right column of FIG. That is, the target specification determining unit 42 determines the target front clearance angle Φ ₀ and the target side clearance angle ε ₀ based on the relationship between the re-grinding amount and the shape error (tooth thickness error) shown in FIG.

The calculation auxiliary value calculation unit 43 calculates the pressure angle approximate value α ₀ , the basic circle diameter Db, and the lead L as calculation auxiliary values, as shown in the center column of FIG. 7 and the center column of FIG. 8 (step S113). .

The manufacturing specification determining unit 44 determines the manufacturing specifications of the gear cutting tool 2 based on the target specifications of the gear cutting tool 2 and the calculation auxiliary value (step S114, manufacturing specification determining step). Specifically, the manufacturing specification determination unit 44 sets the front clearance angle Φ1 and the side clearance angle ε1 as the manufacturing specifications of the gear cutting tool 2 to allowable values from the target front clearance angle Φ ₀ and the target side clearance angle ε ₀ . In order to keep it within the range, the rolling circle diameter D1, pressure angle α1, and helix angle β1 of the gear cutting tool 2 are determined as the manufacturing specifications of the gear cutting tool 2. Steps S111 to S114 can be understood as manufacturing specification determination processing for the gear cutting tool 2 (step S11).

As shown in FIG. 9, details of the manufacturing specification determination section 44 include a rolling circle diameter calculation section 441, a pressure angle/torsion angle calculation section 442, a manufacturing relief angle calculation section 443, and a determination section 444.

Here, the first process (method for determining the manufacturing specifications of the gear cutting tool 2) by the manufacturing specification determining section 44 will be explained with reference to FIG. 11. The rolling circle diameter calculating section 441 calculates the calculation result based on the target front clearance angle Φ ₀ and the target side clearance angle ε ₀ determined by the target specification determining section 42 and the calculation auxiliary value calculated by the calculation auxiliary value calculation section 43. , the rolling circle diameter D1 is calculated (step S1141).

The pressure angle/torsion angle calculation unit 442 calculates the reference circle diameter D stored in the reference specification storage unit 41, the rolling circle diameter D1 calculated by the rolling circle diameter calculation unit 441, and the calculation by the calculation auxiliary value calculation unit 43. Based on the calculated auxiliary values, the pressure angle approximate value α1 and torsion angle β1 are calculated (step S1142).

The manufacturing relief angle calculation unit 443 calculates the rake angle γ stored in the reference specification storage unit 41, the target front relief angle Φ ₀ determined by the target specification determination unit 42, and the pressure angle/torsion angle calculation unit 442. A side clearance angle ε1 is calculated based on the calculated pressure angle approximate value α1 and torsion angle β1 (step S1143).

The determination unit 444 determines whether the side clearance angle ε1 calculated by the manufacturing clearance angle calculation unit 443 is within the allowable range of the target side clearance angle ε ₀ determined by the target specification determination unit 42 ( Step S1144). If the determination unit 444 determines that the side clearance angle ε1 is outside the allowable range of the target side clearance angle _ε0 (step S1144: No), the rolling circle diameter calculation unit 441 calculates a new rolling circle diameter D1. Calculate (step S1145).

Then, the processing from step S1142 to step S1144 is repeated until the determination unit 444 determines that the side clearance angle ε1 is within the allowable range of the target side clearance angle _ε0 . If the determination unit 444 determines that the side clearance angle ε1 is within the allowable range of the target side clearance angle _ε0 (step S1144: Yes), the rolling circle diameter D1, pressure angle approximate value α1, and torsion at that time are determined. Angle β1 is determined (step S1146).

Further, a second process (method for determining manufacturing specifications of the gear cutting tool 2) by the manufacturing specification determination unit 44 will be explained with reference to FIG. 12. Note that the same steps as those shown in FIG. 11 are given the same step numbers. The rolling circle diameter calculating section 441 calculates the calculation result based on the target front clearance angle Φ ₀ and the target side clearance angle ε ₀ determined by the target specification determining section 42 and the calculation auxiliary value calculated by the calculation auxiliary value calculation section 43. , the rolling circle diameter D1 is calculated (step S1141).

The pressure angle/torsion angle calculation unit 442 calculates the reference circle diameter D stored in the reference specification storage unit 41, the rolling circle diameter D1 calculated by the rolling circle diameter calculation unit 441, and the calculation by the calculation auxiliary value calculation unit 43. Based on the calculated auxiliary values, the pressure angle approximate value α1 and torsion angle β1 are calculated (step S1142).

The manufacturing relief angle calculation unit 443 calculates the rake angle γ stored in the reference specification storage unit 41, the target side relief angle ε0 determined by the target specification determination unit 42, and the pressure angle/torsion angle calculation unit 442. The front clearance angle Φ1 is calculated based on the pressure angle approximate value α1 and the torsion angle β1 (step S1147).

The determining unit 444 determines whether the front clearance angle Φ1 calculated by the manufacturing clearance angle calculating unit 443 is within the allowable range (within the allowable value) of the target front clearance angle Φ ₀ determined by the target specification determining unit 42. (Step S1148). If the determining unit 444 determines that the front clearance angle Φ1 is outside the allowable range (outside the allowable value) of the target front clearance angle Φ ₀ (step S1144: No), the rolling circle diameter calculating unit 441 calculates a new The rolling circle diameter D1 is calculated (step S1145).

Then, the processes from step S1142 to step S1144 are repeated until the determination unit 444 determines that the front clearance angle Φ1 is within the allowable range (within the permissible value) of the target front clearance angle _Φ0 . If the determining unit 444 determines that the front relief angle Φ1 is within the allowable range (within the allowable value) of the target front relief angle Φ ₀ (step S1144: Yes), the rolling circle diameter D1 and the pressure angle at that time Approximate value α1 and twist angle β1 are determined (step S1146).

Then, as shown in FIG. 10, the grinding wheel shape and grinding condition determination unit 45 determines the shape and grinding conditions of the grinding wheel 3 based on the manufacturing specifications of the gear cutting tool 2 (step S12, condition determination). process). Specifically, the shape and grinding conditions of the grinding wheel 3 are the number of teeth Z, front clearance angle Φ ₀ or side clearance angle ε ₀ , rake angle γ, helix angle β 1, and rolling in the manufacturing specifications of the gear cutting tool 2. It is determined based on the circle diameter D1.

Steps S11 to S13 can be understood as a process for determining the shape and grinding conditions of the grinding wheel 3 (step S11). The grinding unit 46 grinds the gear 1 using the gear cutting tool 2 based on the determined shape of the grinding wheel 3 and grinding conditions (step S13, grinding process).

According to the grinding method of the gear cutting tool 2, the grinding device 20 (40), and the grinding wheel shape and grinding condition determining device 40a of the present embodiment, the target front relief angle Φ ₀ and the target side relief can increase the amount of re-grinding. The angle ε ₀ is determined, and the manufacturing specifications of the gear cutting tool 2 are determined based on the determined target front clearance angle Φ ₀ and target side clearance angle ε ₀ . Thereby, a gear cutting tool 2 for skiving processing can be obtained, which can increase the amount of re-grinding and simultaneously grind at least the opposing blade side surfaces 2d with one grinding wheel 3. Therefore, the total cost of the gear cutting tool 2 can be reduced at a site where gears 1 are mass-produced.

1: Gear, 1a: Teeth, 2: Gear cutting tool, 2a: Blade, 3: Grinding wheel, 20: Gear cutting tool grinding device, 21: Spindle unit, 22: Grinding head, 40: Processing of gear cutting tool grinding device Apparatus, 41: Reference specification storage unit, 42: Target specification determination unit, 43: Calculation auxiliary value calculation unit, 441: Rolling circle diameter calculation unit, 442: Pressure angle/torsion angle calculation unit, 443: Manufacturing relief angle calculation Part, 444: Determination part, 45: Grinding wheel shape and grinding condition determination part, 46: Grinding part

Claims (8)

A method of simultaneously grinding opposing blade sides of a gear cutting tool used for skiving using a disc-shaped grinding wheel, the method comprising:
Based on the amount of re-sharpening of the gear cutting tool and the shape error of the gear machined by the gear cutting tool, the difference between the reference front clearance angle and the reference side clearance angle as standard specifications of the gear cutting tool is determined. a target specification determining step of determining a target front clearance angle and a target side clearance angle as target specifications of the gear cutting tool;
Determining the manufacturing specifications of the gear cutting tool in order to make the front clearance angle and side clearance angle as manufacturing specifications of the gear cutting tool within tolerance values from the target front clearance angle and the target side clearance angle. manufacturing specification determination process,
a shape and condition determining step of determining the shape and grinding conditions of the grinding wheel based on the manufacturing specifications of the gear cutting tool;
a grinding step of grinding the gear cutting tool under the grinding conditions using the grinding wheel;
A method for grinding a gear cutting tool. The target specifications of the gear cutting tool are specifications in which the shape error of the gear machined by the gear cutting tool with respect to the resharpening amount of the gear cutting tool has an extreme value within a predetermined tolerance. The method for grinding a gear cutting tool according to claim 1. In the manufacturing specification determining step, the target front clearance angle, the target side clearance angle, the pressure angle as the manufacturing specification, the helix angle as the manufacturing specification, and the rake angle as the reference specification are predetermined. The gear cutting tool according to claim 1 or 2, wherein the rolling circle diameter, pressure angle, and helix angle of the gear cutting tool as the manufacturing specifications of the gear cutting tool are determined so as to satisfy the following relationship. Grinding method. The manufacturing specifications determining step includes the target front clearance angle Φ1, the target side clearance angle ε1, the pressure angle α1 as the manufacturing specifications, the torsion angle β1 as the manufacturing specifications, and the reference specifications as the The rolling circle diameter, pressure angle, and helix angle of the gear cutting tool as the manufacturing specifications of the gear cutting tool are determined so that the rake angle γ satisfies equation (1A) as the predetermined relationship. The method for grinding a gear cutting tool according to claim 3.

The gear cutting tool according to claim 3 or 4 , wherein the pressure angle as the manufacturing specification is a pressure angle approximate value determined based on the respective pressure angles of both side blade sides of the gear cutting tool. Grinding method. The pressure angle approximation value _α0 is determined based on equation ( 2A ), the pressure angle _αL of the left blade side surface, and the pressure angle _αR of the right blade side surface of the gear cutting tool, according to claim 5. How to grind a gear cutting tool.

A grinding device that simultaneously grinds opposing blade sides of a gear cutting tool used for skiving using a disc-shaped grinding wheel,
Based on the amount of re-sharpening of the gear cutting tool and the shape error of the gear machined by the gear cutting tool, the difference between the reference front clearance angle and the reference side clearance angle as standard specifications of the gear cutting tool is determined. a target specification determining unit that determines a target front clearance angle and a target side clearance angle as target specifications of the gear cutting tool;
Determining the manufacturing specifications of the gear cutting tool in order to make the front clearance angle and side clearance angle as manufacturing specifications of the gear cutting tool within tolerance values from the target front clearance angle and the target side clearance angle. A manufacturing specification determining department,
a shape and condition determining unit that determines the shape and grinding conditions of the grinding wheel based on the manufacturing specifications of the gear cutting tool;
a grinding section that grinds the gear cutting tool according to the grinding conditions using the grinding wheel;
A grinding device for gear cutting tools. In a grinding method in which opposing blade sides of a gear cutting tool used for skiving are simultaneously ground using a disc-shaped grinding wheel, the grinding wheel shape and grinding conditions are determined. A device,
Based on the amount of re-sharpening of the gear cutting tool and the shape error of the gear machined by the gear cutting tool, different targets are set for the reference front clearance angle and reference side clearance angle as standard specifications of the gear cutting tool. a target specification determining unit that determines a front clearance angle and a target side clearance angle;
Determining the manufacturing specifications of the gear cutting tool in order to make the front clearance angle and side clearance angle as manufacturing specifications of the gear cutting tool within tolerance values from the target front clearance angle and the target side clearance angle. A manufacturing specification determining department,
a shape and condition determining unit that determines the shape and grinding conditions of the grinding wheel based on the manufacturing specifications of the gear cutting tool;
A grinding wheel shape and grinding condition determining device comprising:

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