KR20120085779A - Tool grinding machine - Google Patents

Abstract

The present invention relates to a multi-axis computer controlled machine tool for relief grinding of single-row and multi-row thread hobs 46. The device can be angularly positioned (turn) to correspond to two types of grinding methods: grinding method by cup-shaped grinding wheel 55 and grinding method by pencil-shaped grinding wheel 52. Both the cup-shaped grinding wheel 55 and the pencil-shaped grinding wheel 52 can be used to grind this released geometry of the hob and milling cutter without replacing the grinding spindle assembly or changing the device structure. Or angularly oriented spindles that provide the flexibility of using or using additional device axes for spindle reorientation.

Description

Tool grinding device {TOOL GRINDING MACHINE}

FIELD OF THE INVENTION The present invention relates to machine tools, such as tool grinding devices, and more particularly to multi-axis, high precision computer controlled machining for grinding to a relieved (relief bet) tooth profile of a rotary cutting tool. It's about machines.

When grinding tooth profiles of cutting tools such as gear hobs, worm gear hobs, fixed normal pitch hobs, and milling cutters having a module size larger than 8 modules, the overall tooth profile of both flank and tip contours Multiple grinding wheels are used to complete. As the module size increases from 8 to approximately 16, various approaches to grinding may be used depending on the additional sharpening run to any completed tooth and the width of the groove in the tooth root of the tooth profile. Its additional sharpening run, ie the length of the cam-released tooth surface, can be maximized using a pencil-shaped tapered cone grinding wheel with a relatively small diameter relative to the length. The released length of the teeth depends on the point of interference with the next adjacent teeth of the grinding wheel when the radial cam is grinding the relief along this helix of the hob screw or along the split position in the case of a milling cutter.

Due to the geometry of this groove, there is a practical surface grinding speed limit and bending / shear strength weakening of the tip of the pencil-shaped wheel that must be considered. When approaching the practical application limits of pencil-shaped wheel grinding, other grinding processes may be employed utilizing cup-shaped grinding wheels having a relatively large diameter relative to the width. As a result, the surface grinding speed and strength of the wheel portion for grinding the tooth root portion thereof are overcome. However, a drawback of the cup-shaped grinding wheel is that its large diameter limits the length of the side being cam-released to the point of interference as described above. When the module size exceeds 16 modules and increases to 50 modules, the use of cup-shaped wheels is limited due to the interference of the wheels with the adjacent teeth described above. In most cases, a pencil-shaped tapered cone grinding wheel should be used for this size hob of more than 16 modules to provide a suitable relieving length for the additional sharpening run.

In current tool manufacturing, this blend of profiles generated from multiple grinding wheels and wheel geometries can be used in multiple setups (e.g. up to five setups), this tooth flank, this tip tooth The tip radius and tooth tip outside diameter are ground separately. By means of CNC machine tool operating techniques and rotary truing / dressing devices, the pencil-described above to cover a number of external surfaces such as, for example, this bottom radius / lamp, this pressure angle flank, this tip radius and this tip outer diameter, Profile or cup-shaped grinding wheels can be contoured. In the above example, the finishing grinding process can be reduced to the hybrid profile of only two pencil-shaped or cup-shaped grinding wheels. Probe measurement of a profile using a probe such as Renishaw 3D with ultrasonic touch sensing is based on the positioning of the grinding wheel relative to these reference points on the left and right and the profile of the profile to achieve the required tooth profile and thickness. Helps with hybridization

In the above, many tool manufacturing equipment employ | adopts the several grinding | polishing apparatus dedicated to only one of a pencil-shaped wheel or a cup-shaped wheel. Some tool manufacturing facilities have introduced machine tool designs that allow for the physical orientation (orientation) of pencil-shaped or cup-shaped wheels by replacement of the spindle assembly and drive mechanism. Usually it requires the use of a dedicated grinding device having a physical orientation that can be used for grinding only pencil-shaped wheels or for grinding only cup-shaped wheels. In most but not all cases, cam-releasing motion on a machine tool uses a single axis that provides radial motion for cam relief, which limits the flexibility of the machine.

The present invention can be angularly positioned (turn) to replace the grinding spindle assembly to correspond to two types of grinding methods: grinding method by cup-shaped grinding wheel and grinding method by pencil-shaped grinding wheel. Use both cup-shaped grinding wheels and pencil-shaped grinding wheels to grind these released geometries of hobs and milling cutters without changing the device structure, or use additional device axes for spindle reorientation. A machine tool having an angularly oriented spindle that provides flexibility for use.

1 (a), 1 (b) and 1 (c) show the lead setting angle relationship of the cup-shaped grinding wheel to a universal module size hob tooth profile.
2 (a), 2 (b) and 2 (c) show the lead setting angle relationship of the pencil-shaped grinding wheel to a universal module size hob tooth profile.
FIG. 3 shows the design plane for the radial cam relief movement from the front profile to the rear profile along the involute helicoid.
4 shows the change in pressure angle from the front to the rear of the fixed normal pitch hob tooth profile.
FIG. 5 shows cam-releasing relationships and orientations for hob workpieces and grinding wheel spindles, which are the main components of the device oriented for use with a pencil-shaped grinding wheel.
FIG. 6 shows cam-releasing relationships and orientations for hob workpieces and grinding wheel spindles, which are the main components of the device oriented for use with the cup-shaped grinding wheel. .
7 is an enlarged view of the grinding spindle assembly of the present invention in the operating position in the apparatus.
8 is an enlarged view of an automatic wheel replacement unit attached to the device base for replacing the grinding wheel pack and the refrigerant manifold between the grinding spindle mounting interface and the storage station.

Before describing in detail any feature and at least one configuration of the present invention, it should be understood that the present invention should not be limited to only the detailed configurations illustrated in the following description or the drawings. The invention can be of different configurations and can be practiced and carried out in various ways. Also, the terminology used herein is for the purpose of description and should not be regarded as limiting.

As used herein, the expressions "including", "having", "comprising", and variations thereof are intended to encompass the additional items as well as the items listed thereafter and equivalents to those items. do. The use of phrases to identify elements of a method or process is merely for identification and does not indicate that the elements should be executed in a particular order.

In describing the drawings, reference to directions such as up, down, up, down, rear, bottom, top, front, rear, etc. will be made below. It is done. These directions are not intended to be taken literally or to limit the invention in any form. Also, the terms "first", "second", "third", and the like are used herein for the purpose of description and are not intended to indicate or impart importance or severity.

1 (a), 1 (b) and 1 (c) are a series of hobs along one of the threaded paths (4) of a single or multi-row screw, as one hob tooth (3) of them, a screw involute heli 9 the front profile 5 of the cutting surface defined by the intersection of the cord 2 and the straight or torsion groove 6 and the adjacent hob teeth 9 of the grinding wheel 1 along the involute helicoid 2. Involute Helicoid of one hob tooth (3) with a released rear profile (7) near the end of the sharpening execution section in this position, limited in length by the point of interference (8) The angle relationship of the grinding wheel in the coordinate system with respect to the cup-shaped grinding wheel 1 in contact with (2) is shown. As the relationship defined in Figs. 1 (a), 1 (b) and 1 (c), the fixed angle (HA) 10 of the grinding spindle assembly, the grinding wheel pressure angle (PA) 11, and the axial pressure of the hob teeth Angle (APA) 12, the lead angle of the involute helicoid as viewed from the front (LAS ₁ , LAS ₂ ) 13, the turning setting angle 14 of the grinding head assembly as viewed from the front, and the relieving direction 15 relative to the coordinate system.

2 (a), 2 (b) and 2 (c) are a series of hobs along one of the threaded paths 19 of a single or multi-row screw, with one hob tooth 18 of them, a screw involute heli The front profile 5 of the cutting surface defined by the intersection of the cord 17 and the straight or torsion groove 21 and the adjacent hob teeth 24 of the grinding wheel 16 along the involute heloid 17. Involute Helicoid of one hob tooth 18 with a released rear profile 22 near the end of the sharpening execution section in this position, limited in length by the point of interference 23 with The angle relationship of the grinding wheel in the coordinate system with respect to the pencil-shaped or cone-shaped grinding wheel 16 in contact with (17) is shown. As a relation defined in FIGS. 2 (a), 2 (b) and 2 (c), the fixed angle 25 of the grinding spindle assembly, the true / dressed pressure angle PA on the grinding wheel and the axial pressure of the hob Angle (B) 26, which is the difference between the angles (APA) 27, and the lead angle of the involute helicoid when viewed from the front (LAS ₁ , LAS ₂ ) 28, the turning setting angle 29 of the grinding head assembly as viewed from the front, and the relieving direction 30 relative to the coordinate system.

Figure 3 forms the design planes used to optimize the grinding wheel geometry to reduce the deviation from the theoretical tooth profile with or without involute correction and the inherent error for this pressure angle contact point of the hob tooth grinding wheel. Doing. Design planes are formed in the front zone 31, the middle zone 32 of the cam relief 32, and the rear zone 33. The associated nominal hob outer radius 34, nominal hob middle radius, and nominal hob radius 36 at the end of the sharpening run are also shown.

Figure 4 shows the characteristic error of the hob teeth of the involute profile generated by a conventional machine tool manufacturing method. In theory, each time the hob is sharpened from front to back, a new and different hob is produced. Sharpened hobs are newly created hobs that only cut gears in approximate form. Also, the more the hob is sharpened again, the worse the error. Figure 4 shows no theoretical intrusion modification for the sake of illustration, so that the theoretically correct forward position 37 of the new hob and the sharpened rear position 38 near the end of the grinding run along this involute helicoid Hob shows two axial zones of this involute helicoid profile. Intrinsic error 39 (error A and error B) is characterized by both zones 37 and 38 when a grinding wheel or forming tool having a fundamentally defined geometric profile is driven in a path defined by the device relief movement. Occurs when trying to contact the helicoid surface

An example of recognizing and attempting to resolve the aforementioned inherent error problem is "Spur Gears, author of Buckingham, Earl, published by McGraw-Hill Book Co. Inc., New York, 1928. ), Which discloses a method for releasing hob facets utilizing the special properties of involute helicoids. By this method, the contact between the surface being released and the grinding wheel is the linear generatrix of the involute helicoid, and the surface itself being the involute helicoid. However, this method does not provide any preparation for modifications such as semi-topping ramps, involute corrections and protuberances. In the case of fine pitch hobs (small hobs), the intrinsic error can be ignored, and for low quality large pitch hobs, the magnitude of the error is not critical. In the case of a precision hob, the intrinsic error point can be identified by the following equation.

(1)

(One)

If the Q factor is greater than 20, a hob with a straight axial profile represents an approximate area that will result in cutting a gear with a true involute profile. As the Q factor decreases, the hob tooth axial profile becomes more curved and the probability of intrinsic error increases.

Computer analysis of the grinding wheel contact pattern with this modified involute helicoid, setup angle and offset of the grinding wheel can optimize but not eliminate the grinding process to reduce inherent errors. Calibration device motion to change the pressure angle relationship during the release process can minimize intrinsic errors to an acceptable level to provide a more precise, longer running hob. The grinding wheel head assembly 40 (FIG. 6) of the present invention can provide a grinding wheel rocking motion synchronized with the releasing motion to minimize inherent errors.

The CNC control of the grinding device of the present invention (such as Fanuc's 160iB computer control) is a horizontal plane when the grinding head assembly is positioned around a horizontal plane to use a cup-shaped grinding wheel for grinding. By a single axis moving in, or using a multi-axis to provide cam-releasing motion when the grinding head assembly is positioned around a vertical plane to use a pencil-shaped grinding wheel for grinding. It may be operated to provide radial or offset radial cam relief movement at a compound angle. The grinding head assembly may also impart a rocking motion to the grinding wheel that is added to the radial or offset radial cam-releasing motion, which alters the turning orientation of the grinding wheel relative to the pressure angle of the hob tooth profile. In other words, it acts to reduce this pressure angle in the rear region of the hob teeth relative to the front and middle regions of the tooth profile being released. This motion makes it possible to fabricate fixed normal pitch hobs that could not be produced by the hob grinding method prior to the present invention.

5 shows a table 41, a direct motor driven head stock 42, a live center tailstock 43, a steady rest 44 to assist in loading the arbor assembly, a work holding arbor 45 (FIG. 6), Hob workpiece 46, linear motor driven longitudinal slide assembly 47, linear motor driven vertical slide assembly 48, linear motor driven horizontal radial infeed slide assembly 49, pencil-shaped Pencil with grinding spindle turning assembly 50 oriented for grinding wheel grinding, inclined (preferably 25 degree) grinding spindle housing 51 with spindle 65, and spindle mounting adapter 66 An apparatus of the present invention having a shape grinding wheel 52 is illustrated. Vector 53 illustrates a relative compound angular radial relief motion (ie cam relief motion). Head stock 42 and longitudinal slide assembly 47 create a hob screw lead, and the vertical slide assembly 48 and the horizontal slide assembly 49 combine to produce a cam-releasing motion 53 and a cam Selective rocking of the grinding wheel swing assembly 50 added to the relief movement 53 requires 5-axis synchronization to minimize inherent pressure angle profile errors.

6 shows a table 41, a direct motor driven head stock 42, a live center tailstock 43, a steady rest 44 to assist in loading the arbor assembly, a work holding arbor 45, a hob workpiece ( 46), linear motor driven longitudinal slide assembly (47), linear motor driven vertical slide assembly (48), linear motor driven horizontal radial infeed slide assembly (49), cup-shaped grinding wheel grinding A cup-shaped grinding wheel with a grinding spindle pivot assembly 50 oriented for orientation, an inclined (preferably 25 degree) grinding spindle housing 51 with a spindle 65, and a spindle mounting adapter 66) 52, an apparatus of the present invention having the present invention is illustrated. Vector 56 illustrates a relative compound angular radial relief motion (ie, cam relief motion). Determine the cam screw relieving position of the head stock 42 and the longitudinal slide assembly 47 for generating the hob screw lead, and the horizontal slide assembly 49 has three axes for generating the cam relieving motion 53. Synchronization is required The offset setting angle and vertical axis 48 height of the grinding wheel pivot assembly 50 is held in a fixed position during the cam releasing process during cup-shaped wheel grinding.

The grinding wheel head assembly 40 mounted to move in a vertical direction preferably comprises a variable speed high frequency grinding spindle, and at least positively up to a predetermined set-up compound angle depending on the profile of the grinding wheel, the threaded leads of the cutter and the orientation of the grinding spindle. Or it can automatically swing over a vertical plane arc of minus 120 degrees. The grinding spindle housing 51 preferably has an angular position defined from the vertical turning plane of the grinding wheel head assembly 40 with the grinding wheel close to the workpiece and the direct drive motor of the spindle 65 away from the workpiece. Oriented at an angle of 25 degrees from the vertical turning plane.

The preferred 25 degree orientation of the grinding spindle 65 is a rapid horizontal movement in which the grinding wheel head assembly 40 is positioned at an angle of approximately plus or minus 30 degrees from the horizontal plane and the rotational and longitudinal movements combined with relief grinding. When using the cup-shaped grinding wheel 55 (FIG. 6) in the state of use, additional clearance is provided between the grinding spindle motor housing 51 and the outer diameter of the workpiece. The grinding spindle, which is preferably oriented at 25 degrees, also has the pencil-shaped grinding wheel 52 (FIG. 5) with the grinding wheel head assembly 40 positioned at an angle of approximately plus or minus 40 degrees or its approximation from the vertical plane. Both rapid vertical and horizontal motions combined with rotational and longitudinal motions facilitate the generation of relief grinding motions. In addition to the above-described movements, the grinding wheel head assembly may also have a set-up angle in the relieving movement to create a large modular normal pitch hob that will later correct the tooth profile pressure angle in the rear and front relieving hobs or the flanks. Approximately plus or minus 3.5 degrees may be oscillated from the position. Although a defined 25 degree orientation of the grinding spindle is preferred, the invention is not limited to this. Other angular orientations may be contemplated, which is within the scope of the present application.

7 shows a grinding wheel replacement device cabinet 57, a grinding wheel turning assembly 50 including an inclined grinding spindle 51, a probe 58 for setup and inspection functions (eg, Renishaw 3D). ), And a further device configuration including a table mounted rotary dresser (wheel truing) assembly 59. The automatic grinding of the hobs and the mixing of the multiple wheel profiles are preferably carried out on each tooth flank of the groove by the in-cycle replacement of the grinding wheel pack mounted on the spindle adapter, the use of the probe 58. Determination of rough grinding wheel position relative to the pitch point, acoustic touch sensing to determine the contact position of the grinding wheel profile against the existing tooth profile of the hob, and multiple grinding wheel technologies (CBN) using a table-mounted dresser 59 Contouring using device axes with acoustic touch functionality to generate a grinding wheel profile, including measurement of a ground profile for error correction and hybridization by the probe system 58, and profile Includes automatic analysis and feedback for error correction.

8 shows an automatic wheel replacement with a wheel pack (commonly denoted 62) assembled to a grinding spindle adapter and a number of stations mounted on a rotating carousel 61 storing a corresponding refrigerant manifold 63. An example of a device 60 is shown. The programmable slide assembly 64 facilitates the simultaneous replacement of the wheel pack 62 and the refrigerant manifold 63 between the grinding spindle 51 (FIG. 7) and the plurality of stations on the carousel 61. . Automatic wheel and refrigerant manifold replacement device 60 (located within cabinet 57) is attached to the machine tool to facilitate full automatic grinding of the hob or milling cutter. The automatic wheel changer multi-stages multiple grinding wheels mounted on the spindle adapter with the corresponding refrigerant manifolds, automatically replacing the grinding wheel packs with the refrigerant manifold between the automatic wheel changer and the grinding spindle and thus the entire hob Or it can automatically provide the many wheels needed to complete a milling cutter tooth profile. The standard number of stations in the wheel changer is preferably eight, but an intermediate magazine storage device may be connected to the wheel changer to increase the number of available wheel packs with the refrigerant manifold, limited by availability or space constraints. Can be. Probe systems (eg, Renishaw 3D) are incorporated to provide two-groove setup positioning for multiple grinding wheels while simultaneously providing post-grinding inspection with automatic profile path correction feedback for trueing / dressing. Measurement and reporting of ground profile quality in accordance with the internationally accepted hob and milling cutter specifications of the AGMA (American Gear Manufacturers Association) and DIN (German Industrial Standards Commission) are also planned.

The apparatus of the present invention is capable of grinding single-row and multi-row thread hobs, preferably with a cutting surface defined by a number of straight or torsion grooves, in this size range of approximately 8-50 modules larger than 200 mm outer diameter. The apparatus is also capable of relief grinding of large milling cutters, preferably larger than 200 mm, of which axial division is made and whose cutting surface is defined by a number of straight or torsional grooves. The apparatus is preferably a precision glass scale in any combination of rotary motion, vertical motion, horizontal motion, longitudinal motion and grinding head pivoting motion for carrying out relief grinding of each tooth profile of the hob or milling cutter. It incorporates programmable rapid response direct and linear motor drive axes with position feedback. Tapered or contoured outer diameter hobs can also be ground.

While the invention has been described with reference to preferred embodiments, it should be understood that the invention is not limited to the specific embodiments. It is intended that the present invention include modifications apparent to those skilled in the art without departing from the spirit and scope of the appended claims.

Claims (15)

As a grinding device for grinding a rotary cutting tool,
table;
A workpiece spindle for rotating the workpiece about the workpiece axis;
A tool spindle for rotating the tool about the tool axis;
A vertical assembly having a first side facing the workpiece spindle;
The tool spindle is located on the first side of the vertical assembly and movable vertically along the first side of the vertical assembly, the tool spindle relative to the first side of the vertical assembly Can pivot about a pivot axis extending in an orthogonal direction,
And the tool spindle is inclined and oriented at a predetermined inclination angle with respect to the first side of the vertical assembly. The grinding apparatus according to claim 1, wherein the vertical assembly is located on the table and is movable in at least one of a longitudinal direction of the table and a width direction of the table. The grinding apparatus according to claim 1, wherein the inclination angle is 25 degrees. The grinding apparatus of claim 1, wherein the tool comprises a pencil-shaped grinding wheel. The grinding apparatus of claim 1, wherein the tool comprises a cup-shaped grinding wheel. The grinding apparatus according to claim 1, wherein the tool spindle is located in the pivot assembly and a probe is located on the pivot assembly. The grinding apparatus according to claim 1, further comprising an automatic tool changer comprising a plurality of tool storage stations. 2. The grinding device of claim 1, wherein the grinding device is operable to provide one or more of a radial cam motion and an offset radial cam motion relative to the workpiece. 9. The grinding device of claim 8, wherein the grinding device is operable to additionally impart a rocking motion of the tool added to at least one of the radial cam motion and the offset radial cam motion. The grinding apparatus of claim 1, wherein the workpiece comprises a single threaded hob, a multiline threaded hob, or a milling cutter. As a grinding method of grinding a rotary cutting tool with the grinding wheel provided on the grinding apparatus,
Providing rotation of the rotary cutting tool about a workpiece axis;
Providing rotation of the grinding wheel about a tool axis;
Providing relative movement between the rotary cutting tool and the grinding wheel in up to three directions orthogonal to each other;
A vertically oriented first side of the vertical assembly on the grinding apparatus is directed towards the rotary cutting tool, and the grinding wheel is predetermined relative to the vertically oriented first side of the vertical assembly on the grinding apparatus Providing a pivoting movement of the grinding wheel about a pivot axis orthogonal to the vertically oriented first side of the vertical assembly on the grinding device in an inclined and oriented orientation at an oblique angle of;
Engaging the grinding wheel and the rotary cutting tool with each other and moving the grinding wheel and the rotary cutting tool relative to each other to perform one or more of a radial cam movement and an offset radial cam movement. Grinding method characterized by including. 12. The method of claim 11, further comprising: rocking the grinding wheel to add a rocking motion of the grinding wheel to at least one of the radial cam motion and the offset radial cam motion. Grinding method. 12. The grinding method according to claim 11, wherein the inclination angle is 25 degrees. 12. The method of claim 11, wherein the grinding wheel comprises one of a pencil-shaped grinding wheel and a cup-shaped grinding wheel. 12. The method of claim 11, wherein the workpiece comprises a single threaded hob, a multiline threaded hob or a milling cutter.

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