JP4196206B2 - Cutting method and machining path creation method - Google Patents

Description

  The present invention relates to a cutting method and a method for cutting a shape having a portion having a large cutting area such as a corner portion or a groove portion (in the present specification and claims, for convenience, simply referred to as a corner portion). This relates to a machining path creation method in

  As a method for suppressing excessive cutting load and chatter vibration and performing efficient or high-speed machining in corner cutting, there is a conventional method of reducing the cutting depth in the tool radial direction. (For example, see Patent Documents 1 and 2)

JP 2002-132315 A JP 2002-283118 A

  However, in the above prior art, it is difficult to suppress the occurrence of chatter vibration of the tool at the corner portion (path closest to the wall) even if the cutting amount is reduced in the tool radial direction. Such chatter vibrations occur when the bending direction (tilt direction) of the tool suddenly changes at the corner, and the return of bending occurs and the contact area with the machining surface in the tool axial direction portion increases instantaneously (cutting load also increases). It is thought to be due to the increase. Such a phenomenon is unavoidable if the cutting amount in the tool axis direction is large, even if the cutting amount in the tool radial direction is suppressed. In particular, this tendency becomes prominent when it is necessary to process with a long tool protrusion.

FIG. 12 shows how the bending direction of the tool changes sharply at the corner. As shown in FIG. 12A, the bending direction of the tool 12A in the machining path (tool path) 12B is the arrow A direction before passing the corner part 12C, but in the corner part 12C from the arrow A direction. It changes suddenly in the direction of i. When the bending direction of the tool 12A changes suddenly, the bending return occurs, and the contact range L of the tool axis direction z portion with the machining surface 12D instantaneously increases from L1 to L2, as shown in FIG. This is a cause of chatter vibration of the tool 12A. In the figure, X, Y, and Z indicate respective axes in the three-dimensional space.
Therefore, it is conceivable to reduce the cutting depth in the tool axis direction z. However, this significantly increases the volume in all machining paths, and the calculation amount and calculation time of the machining path, and further, the amount of path data and machining time are extremely increased. is what happened.

The object of the invention described in claim 1 is to increase the volume in all machining paths, that is, without significantly increasing the calculation amount of the machining path, the calculation time, the path data amount, the machining time, etc. An object of the present invention is to provide a cutting method capable of suppressing the generation of excessive cutting load and chatter vibration in a corner portion and capable of speeding up the processing.
An object of the invention described in claim 2 of the claims is to provide a machining path creation method suitable for realizing the cutting method of claim 1.

In order to achieve the above object, the invention according to claim 1 is a method of cutting a shape having a corner portion, wherein the machining path is divided into a corner portion section and a non-corner portion section. For the part section, repeated micro cutting is performed by sequentially repeating the cutting in the tool axis direction with a small cutting amount set smaller than the unit cutting amount in the tool axis direction in the non-corner section section. When the depth of cut is reached, it is characterized in that the process shifts from micro cutting repeated machining in the corner section to the cutting of the next non-corner section following the corner section.
The machining path creation method according to claim 2 of the claims is the machining method according to claim 1, wherein the contour machining path creation method creates a contour-like overall machining path with a unit cut amount in the tool axis direction at the time of cutting. One step, a second step for searching for a corner portion in the entire machining path created in the first step, and a corner portion searched in the second step in the tool axis direction smaller than the unit cut amount A third step of creating an additional path with a set fine cutting depth, and a fourth step of rearranging the entire machining path created in the first process and the corner part additional path created in the third process in the actual machining order. And a fifth step of creating a transfer path that connects the respective processing paths in the corner portion.

In the invention according to claim 1, the machining path is divided into a corner section and a non-corner section, and the corner section has a small cutting amount smaller than a unit cutting amount in the non-corner section. Repeated cutting, repeated micro cutting. Then, when the cutting by the micro cutting repetitive processing reaches the unit cutting amount in the non-corner section, the process shifts from the micro cutting repetitive processing to the cutting of the non-corner section.
According to this, generation | occurrence | production of an excessive cutting load and chatter vibration can be suppressed in the cutting process of a corner part. Also, the increase in machining path calculation amount, calculation time, further path data amount, machining time, etc. (volume in the machining path) does not extend to all machining paths, but is limited to the necessary minimum, that is, the corner part. If it sees as the whole cutting process, the high-speed process by which generation | occurrence | production of the excessive cutting load and chatter vibration was suppressed is realizable.
The invention according to claim 2 of the claims is that, in the first step, a contour-shaped overall machining path is created with a unit cut amount in the tool axis direction at the time of cutting, and in the second process, In the third step, an additional path is created in the tool axis direction with a fine cutting depth set smaller than the unit cutting depth in the third step. In the fourth process, the entire machining path created in the first process and the corner part additional path created in the third process are rearranged in the actual machining order, and in the fifth process, each machining path in the corner part is connected to each other. Since the transfer path is created, the cutting method of claim 1 can be easily realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol shows the same or equivalent part between each figure referred in this specification.
FIG. 1 is an explanatory diagram of an embodiment of a cutting method according to the present invention. In this figure, X, Y, and Z indicate each axis in the three-dimensional space.
The cutting method shown in FIG. 1 is applied when, for example, a rectangular tube or square box shaped machining shape 212 having a corner portion 211 as shown in FIG. 2 is obtained by cutting using an NC machine tool.
In the embodiment shown in FIG. 1, the cutting is performed on the entire processing path 111 on X and Y planes (processing paths shown by abstracting processing paths 1, 8, 15, and 22 described later) at the corner section 112 and the non-corner section. Dividing into the section 113, the corner section section 112 is performed as follows.
That is, the corner section 112 sequentially repeats the cutting in the tool axis direction z with the minute cutting amount C2 set smaller than the unit cutting amount C1 in the tool axis direction z at the time of cutting in the non-corner section section 113. Repeat cutting.
Then, when this micro cutting repetitive processing reaches the unit cutting amount C1 in the tool axis direction z at the time of cutting in the non-corner section 113, the micro cutting repetitive processing in the corner section 112 is changed to this corner section 112. Next, the process shifts to cutting of the next non-corner section 113. That is, the process returns to normal cutting with the unit cutting depth C1.
It should be noted that the extent to which the corner section 112 is set before and after the corner 114 is arbitrarily set.

  The cutting process including the micro-cutting repeated process described above is repeated until the four corner portions 211 (see FIG. 2) make a round. After one round, the tool 115 is lowered by a cutting amount C1 at a predetermined position in the non-corner section 113, that is, the start position (X, Y) of all machining, and cutting including repeated micro-cutting is performed again at the height position (Z). The processing is repeated until the four corner portions 211 (see FIG. 2) are completed. Thereafter, similar cutting is repeated to obtain the illustrated processed shape 212.

  The numbers given to the machining paths in FIG. 1 indicate the machining order in the illustrated corner portion 211. That is, first, cutting by the processing path 1 (cutting by the unit cutting amount C1) is performed, and the tool 115 rises at a predetermined position before the corner section 112 (corner section 211), and then cutting by the processing path 2 I do. When the cutting of the corner section 112 by the machining path 2 is finished, the tool 115 moves to the machining start position by the machining path 3 and performs the machining by the machining path 3. Thereafter, similarly, cutting with the minute cutting amount C2 is repeated up to the machining path 7. That is, micro cutting repeated processing in the corner section 112 is performed. The tool 115 in FIG. 1 shows a state immediately after returning to normal cutting with the unit cutting amount C1 from this minute cutting repeated machining.

When the tool 115 makes a round of the machining path 111 (see FIG. 2) and performs the cutting process by the machining path 8 and reaches a predetermined position before the corner section 112, the tool 115 rises, and then the machining path 9 Perform cutting with. Thereafter, similarly, the cutting with the minute cutting amount C2 is repeated up to the machining path 14.
After that, in the corner section 112, cutting (micro cutting repeated machining) is performed with the minute cutting amount C2 up to the machining paths 16 to 21, and then to the machining paths 23 to 28. In this case, the machining path 16 is a machining path 15, and the machining path 23 is a machining path 22 from the machining path 22.

In FIG. 1, the intervals between the machining paths 1 and 8, 8 and 15, and 15 and 22 are equal to the unit cutting amount C1. Further, the intervals (minute intervals) between the machining paths 2, 3, 3, 4, 4, 5, 5, 6 and 6, 7 are equal to the minute cut amount C 2. The intervals between the machining paths that are carved in the axial direction of the tool 115 between the machining paths 9 to 14, 16 to 21, and 23 to 28 are also equal to the minute cutting amount C2. In this example, the intervals between the machining paths 7 and 9, 14 and 16, and 21 and 23 are also set equal to the minute cutting amount C2.
Here, each machining path 1 to 28 indicates a path at the lower limit position of the cutting effective range in the axial direction z of the tool 115, and is on a contour line (same coordinate value on the Z axis). Further, the dotted line in FIG. 1 indicates the locus (transfer path) of the tool 115 that moves to the next cutting start position every time the cutting of the minute cutting depth C2 is completed in the repeated small cutting in the corner section 112. Is illustrated.

According to such a cutting method, the machining path is divided into the corner section 112 and the non-corner section 113. For the corner section 112, the minute cutting amount C2 is smaller than the unit cutting amount C1 in the non-corner section 113. Since the cutting is repeated and the minute cutting is repeated, it is possible to suppress excessive cutting load and chatter vibration in the corner 211. Specifically, even when a tool 115 having a long protruding dimension (large deflection) is used, the cutting load in the cutting process of the corner portion 211 can be suppressed to be extremely small, and machining with almost no chatter vibration is possible. High-speed feed machining is possible in the part 211.
As a method for suppressing the cutting load to be extremely small, the cutting amount in the tool radial direction is conventionally reduced, whereas in the present invention, the cutting amount in the tool axis direction is reduced. In the conventional method, both the chip thickness at the high peripheral speed portion of the tool in the cutting process and the contact range in the tool axis direction with respect to the machining surface are large, whereas according to the method of the present invention, the above-mentioned chip thickness and tool axis direction are increased. The contact range is both small, and chatter vibration hardly occurs in the method of the present invention.
Further, when the cutting by the micro cutting repetitive processing reaches the unit cutting amount C1 in the non-corner section 113, the micro cutting repetitive processing is shifted to the non-corner section 113 cutting. That is, the increase in the calculation amount of the machining path, the calculation time, further the amount of path data, the machining time, etc. (volume in the machining path) does not extend to the entire machining path, but is limited to the corner section 112. As a result, it is possible to realize high-speed machining in which generation of excessive cutting load and chatter vibration is suppressed.

Next, a method for creating a machining path in the above-described cutting method will be described.
FIG. 3 is a flowchart showing an example of a method for creating the machining path.
First, in step 301, as shown in FIG. 4, contour-shaped overall machining paths 1, 8, 15, and 22 are created with a unit cut amount C1.
In step 302, the corner portion 211 in the overall machining path 1, 8, 15, 22 is searched.
For example, there are methods illustrated in FIGS. 5 to 7 as the search method of the corner portion 211, but any method may be adopted.
FIG. 5 illustrates a method for searching by the folding angle θ of the entire machining paths 1, 8, 15, and 22. If the bending angle θ is an obtuse angle as shown in (a), it is determined as a non-corner portion, and if it is an acute angle as shown in (b), it is determined as a corner portion.
FIG. 6 illustrates a method of virtually searching the remaining machining width w1 of the previous process in a planar manner (imaginary by offsetting the machining path of the own process) and searching with the remaining machining width w1. If the remaining machining width w1 is less than a predetermined threshold value w0 as shown in (a), it is determined as a non-corner part, and if it is equal to or greater than the threshold value w0 as shown in (b), it is determined as a corner part. Is done. Note that Δr in FIG. 6 is a value obtained by subtracting the own process tool radius from the previous process tool radius.
FIG. 7 exemplifies a method of simulating the machining residue (cutting volume) of the previous process by calculation and searching with the cutting volume when simulating the machining path of the own process. If the cutting volume v1 is less than the predetermined threshold value v0 as shown in FIG. 5A, it is determined as a non-corner portion, and if it is equal to or greater than the threshold value v0 as shown in FIG. The

In step 303, only the searched corner portion 211 is created in the tool axis direction z with an additional route (corner portion additional route) with a small cutting amount C2 set smaller than the unit cutting amount.
For example, the corner part addition route creation method includes the method illustrated in FIGS. 8 and 9, and any method may be adopted.
8 and 9 show corner part path copying methods, in which FIG. 8 illustrates a tool axis direction copying method and FIG. 9 illustrates a machining shape copying method. In the tool axis direction copying method illustrated in FIG. 8, the additional path is copied at each height in the tool axis direction z, and in the copying method along the machining shape illustrated in FIG. In each direction).
In addition to the method illustrated in FIG. 8 and FIG. 9, contour processing paths (processing paths 2 to 6, 9 in FIG. 1) are generated in the same manner as the creation method of the entire processing paths 1, 8, 15, 22 in step 301. -13, 16-20, and 23-27), there is a corner path creation method.

  In step 304, the entire machining paths 1, 8, 15, and 22 created in step 301 and the corner part addition path created in step 303 are rearranged in the actual machining order (see FIG. 10). As can be seen from FIGS. 1 and 10, the machining path 7 is the machining path 1, the machining path 14 is the machining path 8, the machining path 21 is the machining path 15, and the machining path 28 is the machining path 22. included.

In step 305, transfer paths (see dotted lines in FIG. 11) that connect the respective processing paths (processing paths 1 to 7, 8 to 14, 15 to 21, and 22 to 28 in FIG. 1) in the corner portion 211 are connected. create.
Steps 303 to 305 are executed for all the corner portions 211 searched in step 302.
According to the machining path creation method described above, the cutting method shown in FIG. 1 can be easily realized.

It is explanatory drawing of one Embodiment of the method of this invention. It is a perspective view which shows an example of the process shape to which this method is applied. It is a flowchart which shows an example of the process path | route preparation method applied to the cutting method shown in FIG. It is a figure which shows an example of the whole process path | route produced in step 301 in FIG. It is a figure for demonstrating an example of the corner part search method in step 302 in FIG. It is a figure for demonstrating another example similarly. It is a figure for demonstrating another example similarly. It is a figure for demonstrating an example of the creation method of the corner part addition path | route in step 303 in FIG. It is a figure for demonstrating another example similarly. It is explanatory drawing of the route rearrangement in step 304 in FIG. It is a figure which shows an example of the transfer route produced in step 305 in FIG. It is a figure for demonstrating generation | occurrence | production of chatter vibration in the cutting process of a corner part.

Explanation of symbols

1 to 28, 111: machining path, 112: corner section, 113: non-corner section, 114: corner, 115: tool, 211: corner section, 212: machining shape, C1: unit cut amount, C2: minute cut amount.

Claims (2)

In a method of cutting a shape having a corner portion,
The machining path is divided into a corner section and a non-corner section, and for the corner section, cutting in the tool axis direction is performed with a small cutting amount set smaller than the unit cutting amount in the tool axis direction in the non-corner section. Repeatedly repeats micro cutting, and repeats micro cutting in the corner section to the next non-corner section following the corner section when the repeated machining reaches the unit cutting depth. The cutting method characterized by shifting. The cutting method according to claim 1,
A first step of creating a contoured overall machining path with a unit cut amount in the tool axis direction during cutting;
A second step of searching for a corner portion in the entire machining path created in the first step;
A third step of creating an additional path with a small cut amount set smaller than the unit cut amount in the tool axis direction for the corner portion searched in the second step;
A fourth step of rearranging the entire machining path created in the first step and the corner part addition route created in the third step in the actual machining order;
A machining path creation method comprising: a fifth step of creating a transfer path that connects the machining paths in the corner portion.

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