TW202338533A - Method for machining workpiece and system for machining workpiece - Google Patents

Abstract

A method for machining a workpiece that is carried out by a machining system has: a first step for finding a first error, which is a contour error of a tool found from an outer shape of a tool as measured by a tool-shaped measurement device; a second step for finding a second error, where a machining error found from the shape of a machining surface of the workpiece as measured by three-dimensional workpiece measurement devices has been converted into the contour error of the tool; and a third step where a movement means moves the tool with the respect to the workpiece on the basis of a prescribed NC program. In the third step, the NC program corrects the position of the tool on the basis of a combined error in which the second error has been added to the first error.

Description

Processing method of the workpiece and processing system of the workpiece

The present invention relates to a processing method of a workpiece and a processing system for the workpiece, and particularly to a method for processing a workpiece by correcting the contour of a tool.

The conventionally known processing system (NC work system) for processing a workpiece has a processing machine (NC machine tool) which is based on an NC program (program) and has a tool (tool) relative to the workpiece (workpiece). Processing is performed on the workpiece while moving.

In conventional NC work systems, tools such as end mills are rotated while relatively moving the tools according to specific numbers (values such as decimals) contained in the NC program to process the workpiece. . Here, Patent Document 1 is disclosed as a representative document of conventional technology.

Furthermore, the applicant proposed a technique (Patent Document 2) in which the position of the held tool is corrected by including an arithmetic expression for calculating the position of the held tool in an NC program. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. Sho 63-233403 [Patent Document 2] Japanese Patent No. 6574915

[Problem to be solved by the invention]

However, there will be a contour error (the difference between the ideal tool contour shape and the actual tool contour shape) in the tool. In machine tools that perform ultra-precision machining, the contour errors of tools such as end mills account for the majority of the shape errors of the workpiece.

According to the technology proposed by the present applicant, the calculation formula for calculating the position of the held tool is included in the NC program to correct the position of the held tool (Patent Document 2), and it is possible to completely eliminate problems caused by the tool. error.

However, it is impossible to correct machining errors caused by factors other than the tool.

Normally, in order to correct machining errors caused by factors other than the tool, the machined shape of the finished workpiece must be measured on or off the NC machine, and the 3D model must be corrected using CAD based on the measurement results. The corrected 3D model is corrected using the CAM correction NC program.

However, there is a problem that the correction of the above-mentioned 3D model requires a lot of work and must consume a lot of time.

The present invention was developed in view of the above-mentioned problems, and its purpose is to provide a processing method and a processing system for a workpiece, which can correct the processing error and implement the workpiece without rewriting the NC program. Processing with good precision. [Technical means to solve problems]

One aspect of the present invention is a processing method of a workpiece performed by a processing system having a workpiece holding means, a tool holding means and a moving means, the workpiece holding means holding the workpiece The workpiece, the tool holding means holds a tool for processing the workpiece held by the workpiece holding means, and the moving means is for using the workpiece held by the tool holding means. The tool performs processing and moves the tool relative to the workpiece. The processing method includes a first step, a second step and a third step. The first step is to obtain a first error, and the first error is derived from The contour error of the tool is calculated from the outer shape of the tool measured by the first measuring device. The second step is to determine the second error. The second error is derived from the shape of the tool measured by the second measuring device. The machining error calculated from the shape of the machined surface of the workpiece is converted into the contour error of the tool. The above-mentioned third process is based on the predetermined NC program, and the above-mentioned moving means moves the above-mentioned tool relative to the above-mentioned workpiece. In the third step, the NC program corrects the position of the tool based on a composite error obtained by adding the second error to the first error.

Another aspect of the present invention is a workpiece processing system for carrying out the above-described method of processing a workpiece. [Effects of the invention]

According to the present invention, the effect of correcting machining errors without rewriting the NC program and processing the workpiece with high accuracy can be exerted.

The processing system 1 for performing the processing method of a workpiece according to the embodiment of the present invention will be described.

FIG. 1 is a schematic structural diagram of a processing system 1 for performing a processing method of a workpiece according to an embodiment of the present invention.

As shown in FIG. 1 , the machining system 1 has an NC machine tool 2 such as a cutting machine (machining center) as a processing machine. In the NC machine machine 2 , a tool 3 (a machining tool: for example, a ball end mill) is used. The processed object (workpiece) 5 is processed.

This NC machine tool 2 includes a workpiece holding part 7 and a tool holding part 9, and the tool holding part 9 is moved in a predetermined direction by a moving part (moving means) 11.

The NC machine tool 2 is connected to a control unit 13 (control device). The control unit 13 includes PC33a or PC33 and CAM39 for creating an NC program used in the control unit 13, based on the NC program created by PC33a or PC33 and CAM39. , the control unit 13 controls the operation of the NC machine tool 2 .

This NC machine tool 2 further includes a tool shape measuring device 31 and a workpiece three-dimensional measuring device 32 . The tool shape measuring device 31 and the workpiece three-dimensional measuring device 32 will be described in detail later.

The workpiece three-dimensional measuring device 32 has been described with an embodiment in which the measurement is performed on the NC machine tool 2. However, as will be described later, the workpiece three-dimensional measuring device 32 may be measured outside the NC machine machine 2.

Furthermore, the gist of the present invention is a technique for correcting the position of the tool by including an arithmetic expression for calculating the position of the tool (the tool that has been held) in the NC program, so as to correct the error caused by the tool (the contour of the tool itself). Errors) and errors caused by factors other than the tool are corrected to process the workpiece (workpiece).

Here, examples of errors caused by factors other than tools include errors caused by the shape of the workpiece, errors caused by individual differences in processing machines, and the like.

The error caused by the shape of the workpiece refers to the error caused by the change of cutting resistance due to the shape of the workpiece, resulting in different machining allowances of the tool. For example, in pocket machining of a square shape, the cutting resistance is small because the tool forms point contact in the straight portion. On the other hand, at the corners, the cutting resistance becomes larger because the contact points of the tool increase. In this case, the cutting resistance changes at the straight portion and the corner portion, and the deflection amount of the tool changes at the corner portion, resulting in cutting residue.

Errors caused by individual differences in processing machines refer to errors caused by differences in the movement trajectories of the tool due to the inherent characteristics of the processing machine. Parameters such as the gain of the servo motor will cause differences in the operation of the processing machine. Especially in the case of machining machines, instead of moving correctly along the specified point on the code specified in the NC program, the movement trajectory of the tool is corrected in a smooth movement. At this time, if there is a difference in the movement of the processing machine, the movement trajectory of the tool will be different. In addition, mechanical deflection caused by the surrounding environment (high temperature environment, etc.) and the influence of the processing machine itself (such as heat generation) may cause the tool position to shift from its original position. In such a situation, the movement trajectory of the tool will also be different.

Although errors caused by factors other than the tool include accidental errors such as disturbances, this specification assumes that machining errors caused by the shape of the workpiece, machining errors caused by individual differences in the processing machine, etc. are reproducible. error.

That is, in the NC machine tool 2 of the embodiment, the first tool error shape including the error caused by the tool 3 measured by the tool shape measuring device 31 is acquired, and the shape measured by the workpiece three-dimensional measuring device 32 is acquired. The second tool error shape that cancels errors caused by factors other than tool 3 is measured, the above-mentioned first tool error shape and the above-mentioned second tool error shape are synthesized, and based on the synthesized tool error shape, the shape caused by tool 3 is The shape of the tool 3 is corrected to process the workpiece by eliminating errors and errors caused by factors other than the tool 3 .

Furthermore, the shape correction of the tool 3 is performed by a technique of correcting the position of the tool 3 by including the calculation expression for calculating the position of the tool 3 in the NC program.

In FIG. 1 , the workpiece holding portion 7 is configured to hold the workpiece 5 . The tool holding part 9 is configured to hold the tool 3 . The workpiece 5 held by the workpiece holding part 7 is processed using the tool 3 held by the tool holding part 9 . An example of processing is cutting processing.

FIG. 2 shows the workpiece 5 and the tool 3 in the NC machine tool 2 according to the embodiment of the present invention. In the following description, a ball end mill is exemplified as the tool 3 . A cutting edge is provided on the outer periphery of tool 3 .

Here, let a predetermined direction in the space be the X direction (X-axis direction; transverse direction), and let another predetermined direction in the space that is orthogonal to the X-direction be the Y direction (Y-axis direction; front-to-back direction). Furthermore, let the direction orthogonal to the X direction and the Y direction be the Z direction (Z axis direction; up and down direction). Under this definition, the X direction and the Y direction become the horizontal direction, and the Z direction becomes the up and down direction, but it is not limited to this. The X direction or the Y direction may be an up-down direction, and the X direction, the Y direction, and the Z direction may be inclined relative to the horizontal direction or the up-down direction.

Furthermore, as shown in FIG. 2 , the tool 3 includes a cylindrical base end portion 15 and a hemispherical front end portion 17 . The outer diameter of the base end portion 15 and the diameter of the front end portion 17 are consistent with each other, and are formed in a shape such that one end of the base end portion 15 in the extending direction of the central axis C1 is connected to the front end portion 17 . The central axis of the distal end portion 17 and the central axis C1 of the base end portion 15 coincide with each other.

In this embodiment, a ball end mill is used as the tool 3 for explanation. However, the tool 3 is not limited to this. A radius end mill (radius end mill; an end with a flat bottom surface and a rounded corner R) may also be used. milling cutter) and other tools.

Here, the center of the circular end surface of the distal end portion 17 (the end surface connected to the circular end surface of the base end portion 15 ) is set as the center C2 of the distal end portion 17 . This center C2 is located on the central axis C1 of the tool 3 .

The cutting edge of the tool 3 is formed on the outer periphery of the tip portion 17 and the end portion of the base end portion 15 (the end portion on the tip portion 17 side). The other end of the base end 15 of the tool 3 is engaged with the tool holding part 9 and is held by the tool holding part.

And by rotating the tool 3 held by the tool holding part 9 (rotating about the central axis C1 as a rotation center), the workpiece 5 is cut using the cutting edge.

The moving part 11 is configured to move the tool 3 relative to the workpiece 5 in order to process the workpiece 5 using the tool 3 . That is, the tool 3 may be moved relative to the workpiece 5 , or the workpiece 5 may be moved relative to the tool 3 .

The control unit 13 is configured to move the tool 3 relative to the workpiece 5 by controlling the moving unit 11 based on the NC program.

Furthermore, as shown in FIG. 1 , the NC machine tool 2 for the workpiece 5 includes a base 19 , a table 21 , a machine column 23 , a spindle support 25 , a spindle housing 27 , and a spindle 29 .

The table 21 is supported by the base 19 through a linear guide bearing (not shown), and is relatively moved (moved and positioned) in the X direction with respect to the base 19 by an actuator such as a linear motor (not shown).

The machine column 23 is integrated with the base 19 . The spindle support 25 is supported by the machine column 23 through a linear guide bearing (not shown), and moves relative to the machine column 23 in the Y direction by an actuator such as a linear motor (not shown).

The spindle housing 27 is supported by the spindle support 25 through a linear guide bearing (not shown), and moves relative to the spindle support 25 in the Z direction by an actuator such as a linear motor (not shown).

The spindle 29 is supported by the spindle housing 27 through bearings, and is rotated relative to the central axis (the common central axis of the tool 3 extending in the Z direction) C1 by an actuator such as a motor (not shown). The spindle housing 27 is rotatable.

The tool holder 9 is provided on the spindle 29 , and the workpiece holder 7 is provided on the upper surface of the table 21 . Thereby, the tool 3 moves relative to the workpiece 5 in the X direction, the Y direction, and the Z direction.

Next, the first tool error shape for eliminating the contour error (first error) of the tool 3 measured by the tool shape measuring device 31 will be described.

Furthermore, the NC program includes an arithmetic expression (for example, a mathematical expression using four arithmetic operations, etc.) for calculating the position of the tool 3 (coordinates with respect to the workpiece 5), as will be described later.

That is, the present invention is configured to synthesize the first tool error shape described below and the second tool error shape described below, and determine the time when moving the tool 3 based on the synthesized tool error shape based on the solution of the above calculation expression. the corrected position coordinates.

The position of the tool 3 is corrected using the normal vector V1 of the processing surface relative to the processing point T1 of the tool 3 (details will be described later) and the contour error of the tool 3 . Thereby, the three-dimensional position of the tool 3 is corrected in at least any one of the X direction, the Y direction, and the Z direction (determined according to the shape of the normal vector V1).

Furthermore, the contour error of the tool 3 is determined in advance by the tool shape measuring device 31 shown in FIG. 1 before the workpiece 5 is actually processed.

The tool shape measuring device 31 is installed at a predetermined position of the NC machine tool 2 . Then, the tool 3 is positioned at a position where the tool shape measuring device 31 (laser, camera, etc.) can measure the shape of the tool 3, and the tool 3 is rotated (rotated about the central axis C1), whereby the tool 3 is rotated on the machine (the NC machine tool 2). On the machine) determine the shape of tool 3.

The difference between the measured outer shape of the tool 3 and the ideal outer shape of the tool 3 (the outer shape of the tool 3 without shape error) (difference in each part of the tool 3) is defined as the contour error of the tool 3 itself (the first error ).

FIG. 3 is an explanatory diagram of the contour error (first error) of the tool in the machine for processing a workpiece according to the embodiment of the present invention.

The dotted line in Fig. 3(a) represents the ideal outer shape of the tool 3, and the solid line in Fig. 3(a) represents the actual outer shape of the tool 3 with shape error. In FIG. 3(a) , the tool is not rotated around the central axis C1. In addition, the tool 3 shown by the solid line in Figure 3(a) is located slightly to the right relative to the central axis C1.

The dotted line in Fig. 3(b) represents the ideal shape of the tool 3, and the solid line in Fig. 3(b) represents the actual tool 3 with shape error (the tool 3 shown by the solid line in Fig. 3(a)). The appearance when the central axis C1 rotates.

The outer shape of the tool 3 shown by the solid line in Fig. 3(b) is, of course, line symmetrical with respect to the central axis C1. If the workpiece 5 is processed by the front end 17 of the tool 3, as shown in Figure 4, the contour error of the tool 3 can be obtained as long as 1/4 of the arc of the front end 17 (that is, the angle range of 90˚) That’s it.

FIG. 4 is an explanatory diagram of the contour error (first error) of the tool in the machine for processing a workpiece according to the embodiment of the present invention.

The tool shape measuring device 31 is disclosed in Japanese Patent Application Laid-Open No. 63-233403, for example.

Details of the process of eliminating the contour error of the tool 3 measured by the tool shape measuring device 31 are described in Japanese Patent No. 6574915 filed by the applicant.

Next, in order to eliminate errors (machining errors) caused by factors other than the tool 3 , a second tool error shape based on machining errors such as cutting residues of the workpiece 5 measured by the workpiece three-dimensional measuring device 32 will be described.

First, the workpiece three-dimensional measuring device 32 for measuring the machined shape of the workpiece 5 on the NC machine tool 2 will be described. Figure 5 is a schematic diagram of a three-dimensional workpiece measurement device composed of a touch sensor on an NC machine tool.

As its schematic structure is shown in FIGS. 1 and 5 , the workpiece three-dimensional measurement device 32 is composed of a touch sensor generally called a touch probe.

The spindle housing 27 of the spindle support 25 of the NC machine tool 2 is equipped with a touch sensor 32 that is separate from the tool 3 and can be replaced with the tool 3 . The touch sensor 32 is used to measure the size of the processed surface of the workpiece 5 processed by the NC machine tool 2 .

Furthermore, the data on the shape of the machined surface of the workpiece 5 measured by the touch sensor 32 is sent to the PC 33a and stored.

This workpiece 5 is the same as the workpiece 5 (sample) completed by subsequent formal processing. Therefore, the processed surface of the workpiece 5 becomes the same as the processed surface completed by the actual processing.

In PC33a, as will be described later, the measured points (design values), shape errors, and measurement points of the measured machined surface of the workpiece 5 are obtained using predetermined software based on the data on the measured dimensions of the machined surface of the workpiece 5. Vector etc.

In the case of the workpiece three-dimensional measurement device 32 composed of an on-machine touch sensor shown in FIG. 5 , the processed workpiece 5 does not need to be moved from the NC machine tool 2 to measure the workpiece 5 . Machined surface.

However, in this case, the spindle housing 27 of the spindle support 25 of the NC machine tool 2 must be equipped with a touch sensor 32 that is separate from the tool 3 .

In the above embodiment, as the workpiece three-dimensional measuring device 32 , a touch sensor is used on the NC machine tool 2 to measure the processed shape of the workpiece 5 . However, as another embodiment, the workpiece three-dimensional measuring device 51 that measures the processed shape of the workpiece 5 outside the NC machine tool 2 can also be used.

FIG. 6 is a schematic diagram of a workpiece three-dimensional measuring device 51 for measuring the machined shape of the workpiece 5 outside the NC machine tool 2 .

As shown in FIG. 6 , the workpiece three-dimensional measuring device 51 has a workbench 53 for placing the workpiece 5 processed by the NC machine tool 2 at a predetermined position, and a workpiece 5 placed on the workbench 53 . The shape sensor 55 above measures the processed surface of the workpiece 5 after processing. The shape sensor 55 is moved up, down, left and right relative to the fixed workpiece 5 to measure the processed surface of the workpiece 5 .

Here, the external workpiece three-dimensional measurement device 51 of the NC machine tool 2 obtains the measurement point (design value), the shape error, and the normal vector of the measurement point based on the measured size data of the processing surface of the processing workpiece 5 etc. and sent to PC33a.

In the case of this embodiment, it is of course necessary to have a workpiece three-dimensional measuring device 51 that measures the processed shape of the workpiece 5 outside the NC machine tool 2 to obtain its measurement points (design values), shape errors, normal vectors of the measurement points, etc. .

Next, a processing procedure of a processing machine for a workpiece (workpiece) according to an embodiment of the present invention will be described with reference to FIG. 7 .

FIG. 7 is a flowchart of a processing procedure of the workpiece processing machine according to the embodiment of the present invention.

First, in step S11 of FIG. 7 , an NC program for processing the workpiece 5 is generated based on a commercially available CAM, that is, the three-dimensional coordinates based on the processing path of the tool 3 are generated. Here, a ball end mill is used as the tool 3 .

Next, in step S12, a correction vector (normal vector) is added to the NC program, and in step S13, the NC program is loaded into the control unit 13 of the NC machine tool 2.

The processing of steps S11 to S13 is performed using the PC33a or PC33 and CAM39 that create the NC program.

Here, the position of the tool 3 is corrected using the normal vector of the processing surface at the processing point of the tool 3 and the contour error of the tool 3 . Thereby, the three-dimensional position of the tool 3 is corrected in at least any one of the X direction, the Y direction, and the Z direction (determined according to the shape of the normal vector).

Next, the process of eliminating errors caused by the tool 3 and errors caused by factors other than the tool in steps S14 to S16 described below will be described.

First, in step S14, the shape of the tool 3 for processing the workpiece 5 is measured using a tool shape measuring device 31 such as a laser, and the outline error of the tool 3, that is, the first error is determined from the shape of the tool 3. The first tool error shape is obtained from the first error (first step). The first tool error shape refers to the contour shape of the tool 3 including the first error.

That is, as shown in FIG. 1 , the tool shape measuring device 31 is installed at a predetermined position of the NC machine tool 2 so that the tool 3 is positioned at a position that can be measured by the tool shape measuring device 31 (laser, camera, etc.). The tool 3 rotates (rotates around the central axis C1), thereby measuring the outer shape of the tool 3 on the machine (on the machine of the NC machine tool 2).

The difference between the measured outer shape of tool 3 and the ideal outer shape of tool 3 (the outer shape of tool 3 without shape error) (difference for each part of tool 3) is determined as the contour error of tool 3 (first error) . The ideal shape of the tool 3 is stored in the control unit 13 as shape data, and is defined based on the shape and size of the tool 3 .

FIG. 8 is an explanatory diagram showing the shape of the first tool error based on the contour error of the tool. As described above, if the contour error of the tool 3 is measured at every minute angle of 0.1˚, for example, a small wave-like contour error CV1 can be obtained as shown in the curve of FIG. 8(a) .

If high-frequency components are filtered out from the curve (contour error CV1) shown in FIG. 8(a) , a certain degree of wavy contour error CV2 as shown in the curve in FIG. 8(b) can be obtained. As described below, the contour shape of the tool 3 including the contour error CV2 shown in the curve of FIG. 8(b) is corrected as the first tool error shape (hereinafter referred to as "first tool error shape CV2").

FIG. 9 shows the processing range of the workpiece that changes depending on the radius of the arc of the tool 3 and the radius of the arc of the machined surface of the workpiece. When the difference between the radius of the arc of the tool 3 and the radius of the machined surface of the workpiece 5 is small, the CT3 value of the contact length (contact area) between the workpiece 5 and the tool 3 becomes larger.

In this way, even if the shape of the tool 3 for processing the workpiece 5 is measured by using the tool shape measuring device 31 such as a laser, the first error is obtained from the shape of the tool 3, and the first error is obtained from the first error. As for the tool error shape, tool correction based only on the first tool error shape may still cause errors (machining errors) caused by factors other than the tool 3 .

In order to cope with such machining errors, the present invention performs the processing below step S15 and below.

In step S15 of FIG. 7 , in order to eliminate processing errors caused by factors other than the tool 3 , the second error is obtained from the processed workpiece measured by the workpiece three-dimensional measuring device 32 The machining error calculated from the shape of the machined surface of 5 is converted into the contour error of the tool 3, and the second tool error shape is obtained from this second error (second step). The second tool error shape refers to the contour shape of the tool 3 including the second error.

Described in detail below, the contour error of the tool 3 is obtained from the shape of the machined surface of the workpiece 5 measured by the workpiece three-dimensional measuring device 32, and the calculation of the second tool error shape including the contour error of the tool 3, that is, the second error. Come up with a method.

First, trial processing is performed on the trial workpiece 5 . During trial processing, the moving unit 11 moves the tool 3 relative to the trial workpiece 5 based on the NC program. At this time, the NC program performs position correction of the tool 3 based on the correction amount of the NC program described below. That is, the NC program corrects the position of the tool 3 based on the first tool error shape CV2 including the first error. Thereby, the machining error of the workpiece 5 based on the contour error of the tool 3 is corrected, and the tool 3 is operated, thereby processing the trial workpiece 5 .

As shown in FIG. 5 , the shape of the machined surface of the workpiece 5 after processing is measured by the workpiece three-dimensional measuring device 32 composed of a touch sensor on the NC machine tool 2 .

That is, before formal processing, the front end of the touch sensor 32 is brought into contact with the machined surface of the test workpiece 5 processed by the NC machine tool 2, thereby measuring the shape of the machined surface of the test workpiece 5.

Here, the workpiece 5 used for the trial is the same as the workpiece 5 used for the actual processing later (test piece). Therefore, the machined surface of the workpiece 5 for trial use is also the same as the machined surface of the workpiece 5 for formal machining that is completed by formal machining.

The front end of the touch sensor 32 is brought into contact with the machined surface of the workpiece 5 to be tested, whereby the shape of the machined surface of the workpiece 5 to be tested is measured by the touch sensor 32 . The measurement data is sent to and stored in the PC 33 a that creates the NC program used in the control unit 13 .

In PC33a, based on the measured dimensions of the machined surface of the workpiece 5 to be tested, predetermined software is used to obtain measurement points (design values), shape errors, normal vectors of the measurement points, etc.

That is to say, PC33a uses the measurement software for machine tools developed by Hexagon, a three-dimensional measuring machine manufacturer, for example, and performs measurements from the CAD approach from the normal vector direction relative to the measurement point, enabling high-end on-machine measurement. Measure to obtain the measurement point (design value), shape error, normal vector of the measurement point, etc.

Furthermore, PC33a is performed based on the measurement points (design values) of the test workpiece 5 obtained using the above-mentioned measurement software for machine tools, the shape error, the normal vector of the measurement points, and the CAD model representing the shape of the ideal workpiece after processing. Compare, calculate and find out which part of the machined surface 5a of the workpiece 5 has the machining error.

FIG. 10 is a schematic diagram showing how the shape of the processed surface 5 a of the workpiece 5 is measured by the workpiece three-dimensional measuring device 32 including the touch sensor shown in FIG. 5 .

In FIG. 10 , as an example of the machining error, there is a cutting residue of 2 μm on the 45° surface of the machined surface 5 a of the workpiece 5 for trial use.

In this embodiment, the workpiece three-dimensional measuring device 32 composed of a touch sensor is used on the NC machine tool 2 to measure the machined surface 5a of the workpiece 5 subjected to the test operation. On the PC 33a, based on the measured Based on the dimensional data of the machined surface of the workpiece 5 used in the test, the measured points (design values), shape errors, normal vectors of the measured points, etc. are obtained using established software on the PC33a.

However, the above-mentioned workpiece three-dimensional measuring device 51 can also be used outside the NC machine tool 2 to measure the shape of the machined surface of the test workpiece 5, and obtain the measurement points (design values), shape error, and measurement from the measurement data. The normal vector of the point, etc.

Next, the PC 33a calculates which part of the machined surface 5a of the workpiece 5 on which the test is performed has a machining error. PC33a extracts the tool profile shape including the profile error of the tool 3 calculated in order to offset the machining error of the machining surface 5a of the workpiece 5 from the calculation data, and uses it as the second tool error shape 3a1.

Figure 11 is a schematic diagram showing the second tool error shape. When the machining error illustrated in Figure 10 is a cutting residue of 2 μm on the surface near 45° of the machined surface 5a of the workpiece 5, the second tool error shape is As tool outline shape containing correction values for tool 3. In Figure 11, the solid line represents the tool outline shape, and the dotted line represents the tool outline shape including the correction value.

As shown by the dotted line in Fig. 11, the tool contour shape including the correction value of the dotted line becomes the second tool error shape 3a1, which is used to offset the machining error illustrated in Fig. 10 and is used in the test processing of the workpiece 5. 2μm cutting residue on the surface near 45˚ of surface 5a.

Here, the second tool error shape 3a1 is a concave shape that cancels out the 2 μm cutting residue on the surface near 45° of the machined surface 5a of the workpiece 5 for trial use.

That is, when the workpiece 5 under test is left with cutting residue, it can be considered that the tool shape has a depression. Therefore, by providing the recess in the correction value of the tool shape, the correction function is performed as if the tool has the recess, so the cutting residue of the workpiece 5 can be removed.

When overcutting occurs on the machined surface 5a of the workpiece 5 under test, the second tool error shape becomes a convex shape that offsets the overcutting.

Next, in step S16, the control unit 13 synthesizes the first tool error shape CV2 and the second tool error shape 3a1 to create a synthesized tool error shape (CV2+3a1) (fourth step).

That is, the first tool error shape CV2 including the contour error (first error) of the tool shown in FIG. 8 and the second tool error shape 3a1 including the contour error (second error) of the tool 3 shown in FIG. 11 Overlap and combine to obtain the combined tool error shape (CV2+3a1) as shown in Figure 12. That is, the combined tool error shape (CV2+3a1) is a tool error shape including a combined error obtained by adding the first error and the second error.

Specifically, the contour of the tool 3 from the first transition point X1 to the second transition point X2 of the second tool error shape 3a1 shown in FIG. 11 is used instead of the wavy contour shown in the curve CV2 of FIG. 8(b) , and the synthetic tool error shape (CV2+3a1) as shown in Figure 12 is obtained.

That is, the transition points X1 and X2 at which the second tool error shape 3a1 transitions to the concave shape that cancels the cutting residue are obtained, and the contour between the transition points X1 and X2 in the first tool error shape CV2 is calculated using the above-mentioned The composite tool error shape is obtained instead of the concave shape of the second tool error shape 3a1.

FIG. 12 is an explanatory diagram showing a composite tool error shape (CV2+3a1) obtained by overlaying and synthesizing the first tool error shape CV2 and the second tool error shape 3a1.

In fact, of course, the shape of the tool 3 shown by the solid line in Fig. 3(b) is line symmetrical with respect to the central axis C1.

That is, since the tip portion 17 of the tool 3 becomes linearly symmetrical with respect to the central axis C1, as shown in FIG. 12 , the contour error of the tool 3 becomes the same on the left and right within a quarter arc (that is, within the range of an angle of 90˚). .

Therefore, if the workpiece 5 is processed by the front end 17 of the tool 3, as long as the contour error of the tool 3 is found on the 1/4 arc of the front end 17 (that is, the range of the angle 90˚) on either the left or right, that is Can.

Next, in step S16, the correction amount of the NC program is calculated based on the combined tool error shape (CV2+3a1) obtained by overlapping and combining the first tool error shape CV2 and the second tool error shape 3a1 as shown in FIG. 12. This correction amount is set in the memory 35 of the control unit 13 and the like.

Here, the NC program includes an arithmetic expression (for example, a mathematical expression using four arithmetic operations, etc.) for calculating the position of the tool 3 (coordinates with respect to the workpiece 5). That is, the position coordinates when moving the tool 3 are determined by the solution of the calculation expression.

That is, the NC program is configured to correct the position of the tool 3 according to the correction amount using an arithmetic expression in order to eliminate the machining error of the workpiece 5 based on the contour error of the tool 3 and to eliminate the machining error caused by factors other than the tool. .

In other words, if specific numbers are used, the NC program must be rewritten every time when the processing machine is changed, when the tool is replaced, when the tool wears out, etc. However, by using calculation expressions, it is possible to respond to frequently changing tool contour errors at any time.

By using arithmetic expressions, the measured tool contour values are stored in variables and calculated (calculated) during machining. Therefore, the NC program only needs to be created once and can be used continuously thereafter. In addition, since the calculation of the calculation expression of the NC program is performed by the control unit 13, no special device is required.

Further, the correction of the tool position using the above calculation formula is described in detail in Japanese Patent No. 6574915 filed by the present applicant.

In the case of this embodiment, the process of obtaining the above-mentioned synthetic tool error shape (CV2+3a1) is executed in PC33a. However, the above-mentioned synthesis processing can also be performed on PC33 and CAM39 other than PC33a.

Then, in step S17, actual machining by the tool 3 in the NC machine tool 2 is started. The moving part 11 moves the tool 3 relative to the workpiece 5 for actual processing based on the NC program (third step).

At this time, the NC program performs position correction of tool 3 based on the correction amount of the NC program. That is, the NC program corrects the position of the tool 3 based on the tool error shape including the composite error obtained by adding the first error and the second error. In this way, the machining error of the workpiece 5 based on the contour error of the tool 3 and the machining error of the workpiece 5 caused by factors other than the tool 3 can be corrected and the tool 3 can be operated, thereby processing the workpiece 5 .

According to the NC machine tool 2 of this embodiment, the contour error of the tool 3 can be eliminated, and further, the machining error caused by factors other than the tool 3 can be eliminated, so that very precise machining can be achieved.

Furthermore, according to the NC machine tool 2 of this embodiment, since the NC program includes an arithmetic expression for calculating the position (coordinate value) of the tool 3, it is not necessary to rewrite the NC program every time when the tool is replaced, when the tool wears out, etc. .

The present invention is not limited to the embodiments of the invention described above, and can be implemented in other aspects by making appropriate changes.

For example, in addition to the above-mentioned correction of errors caused by the tool 3 and errors caused by factors other than the tool 3 , the wear amount of the tool 3 from the start to the end of the processing of the workpiece 5 by the tool 3 may also be measured. In addition to the above-mentioned machining errors caused by factors other than the tool 3, the shape of the tool 3 changed due to the wear amount is also considered to correct the NC program to process the workpiece 5 with higher precision.

Further, the correction of the NC program taking into account the change in the shape of the tool 3 due to the amount of wear is described in detail in Japanese Patent No. 6574915 filed by the present applicant.

In the above-mentioned embodiment, the first tool error shape CV2 including the contour error of the tool shown in FIG. 8 and the second tool error shape 3a1 including the contour error of the tool 3 shown in FIG. 11 are overlapped and combined to obtain the figure. In the case of the synthetic tool error shape (CV2+3a1) as shown in Figure 12, the second tool error shape 3a1 shown in Figure 11 is replaced by the outline of the tool 3 from the first transition point X1 to the second transition point X2. The wavy contour error CV2 shown in the curve of 8(b) is used to obtain a synthesized tool error shape (CV2+3a1) as shown in FIG. 12. However, the shape is not limited to this, and the synthesis may be performed as follows.

That is, the part corresponding to the surface near 45° of the machined surface 5a of the workpiece 5 in the wavy contour error CV2 shown in the curve of Fig. 8(b) may be added to the part including the part shown in Fig. 11 The second tool error shape 3a1 of the contour error of tool 3 is used to obtain the synthetic tool error shape (CV2+3a1).

It is also used as a means of measuring the shape of the machined surface of the workpiece 5 and obtaining measurement points (design values), shape errors, normal vectors of the measurement points, etc. from the measurement data. It is used on the NC machine tool 2 based on the touch sense. The workpiece is measured by the three-dimensional measuring device 32 composed of a measuring instrument. In the PC33a, based on the measured dimensional data of the processing surface of the workpiece 5, predetermined software is used on the PC33a to obtain the measurement point (design value), shape error, and measurement. The normal vector of the point, etc., or the workpiece three-dimensional measuring device 51 that obtains the measured point (design value), the shape error, the normal vector of the measured point, etc. is used outside the NC machine tool 2, but it is not limited to this, as long as The shape of the machined surface of the workpiece 5 can be measured, and measurement points (design values), shape errors, normal vectors of the measurement points, etc. can be obtained from the measurement data, regardless of the shape.

In the above embodiment, the trial workpiece 5 is processed before the actual processing, and the machining error of the workpiece 5 based on the contour error of the tool 3 and the machining error of the workpiece 5 caused by factors other than the tool 3 are corrected. That is, the outline of the processing method of this embodiment is as follows.

(1) Before trial processing, the shape of the tool 3 is measured to obtain the first tool error shape (step S14 in FIG. 7 ). (2) Perform trial processing on the trial workpiece 5. (3) The machined surface of the trial workpiece 5 is measured to obtain the second tool error shape (step S15 in FIG. 7 ). (4) The first tool error shape and the second tool error shape are combined to obtain a combined tool error shape, and the correction amount is calculated from the combined tool error shape and set in the control unit 13 (step S16 in FIG. 7 ). (5) Using the calculated correction amount, the workpiece 5 for actual processing is processed (step S17 in FIG. 7 ).

Of course, the processing method of this embodiment may be implemented in actual processing without performing trial processing. For example, the processing method of this embodiment is performed during the initial processing of the workpiece 5 for actual processing. The outline of the processing method in this case is as follows.

(1) Before actual processing, measure the shape of the tool 3 to obtain the first tool error shape (corresponding to step S14 in FIG. 7 ). (2) Process the workpiece 5 for formal processing. (3) Measure the machined surface of the workpiece 5 for actual machining to obtain the second tool error shape (corresponding to step S15 in FIG. 7 ). (4) The first tool error shape and the second tool error shape are combined to obtain a combined tool error shape, and a correction amount is calculated from the combined tool error shape and set in the control unit 13 (corresponding to step S16 in FIG. 7 ). (5) In the second and subsequent machining operations, the workpiece 5 for formal machining is subjected to formal machining using the calculated correction amount (corresponding to step S17 in FIG. 7 ).

In addition, for the second and subsequent processing, the above-mentioned steps (2) to (5) may be performed for each processing, or the above-mentioned steps (2) to (5) may be performed periodically when the number of processing reaches a certain number. In addition, when the formal machining includes a plurality of processes such as rough machining, intermediate machining, and finishing machining, it is preferable to measure the machined surface of the workpiece 5 for formal machining after the final finishing process. When measuring the machined surface of the workpiece 5 for formal machining, if there is no machining error or the machining error is smaller than the reference value for judging good machining, the steps (4) to (5) can be skipped.

The former shows a method of correction using trial processing, and the correction of the processing error is reflected in the actual processing. In the former method, the main processing in (5) is performed on the workpiece 5 for main processing, and the workpiece 5 for main processing is a test workpiece in which the second tool error shape is obtained by measuring the machined surface in (3). 5 different. On the other hand, in the case of the latter method of performing correction during actual machining, the correction of the machining error may be reflected in the actual machining of the workpiece 5 for the next actual machining, or may be reflected in the actual machining of the same workpiece 5. When the workpiece 5 is used for correction processing. That is, in the latter method (5), the main processing can be performed on a new workpiece for main processing that is different from the workpiece 5 for main processing in which the second tool error shape is obtained by measuring the machined surface in (3). 5 may be performed, or may be performed on the workpiece 5 for actual machining in which the second tool error shape is obtained by measuring the machined surface in (3).

1: Processing system 2:NC working machinery 3: Tools (ball end mill) 3a1: 2nd tool error shape 5: Processed object (workpiece) 5a: Processing surface 7: Workpiece holding part 9: Tool holding part 11:Mobile Department 13:Control Department 31: Tool shape measuring device 32: Workpiece three-dimensional measurement device (touch sensor) 51: Workpiece three-dimensional measuring device 33:PC 39:CAM 41,43: Processing path C1: Central axis C2: Center CV1: Contour error CV2: 1st tool error shape (contour error) T1: Processing point X1: 1st transfer point X2: 2nd transfer point

[Fig. 1] is a schematic configuration diagram of a processing system that performs a processing method of a workpiece according to an embodiment of the present invention. [Fig. 2] shows a workpiece and a tool in a machine for processing a workpiece according to the embodiment of the present invention. [Fig. 3(a), (b)] are explanatory diagrams of the contour error (first error) of the tool in the processing machine of the workpiece according to the embodiment of the present invention. [Fig. 4] It is an explanatory diagram of the contour error (first error) of the tool in the processing machine of the workpiece according to the embodiment of the present invention. [Fig. 5] A schematic diagram of a three-dimensional workpiece measuring device composed of a touch sensor mounted on an NC machine tool. [Fig. 6] is a schematic diagram of a three-dimensional workpiece measuring device for measuring the machined shape of the workpiece 5 outside the NC machine tool. [Fig. 7] A flowchart showing a processing procedure of a processing machine of a workpiece in the processing system shown in Fig. 1. [Fig. [Fig. 8(a), (b)] are explanatory diagrams showing the shape of the first tool error based on the contour error of the tool. [Fig. 9] is an explanatory diagram showing the processing range of the workpiece that changes depending on the radius of the arc of the tool and the radius of the arc of the machined surface of the workpiece. [Fig. 10] is a schematic diagram showing how the shape of the machined surface of the workpiece is measured by the workpiece three-dimensional measuring device composed of the touch sensor shown in Fig. 5. [Fig. [Figure 11] is an explanatory diagram showing the second tool error shape. When the machining error illustrated in Figure 10 is a cutting residue of 2 μm on the 45° surface of the workpiece, the second tool error shape is As tool outline shape containing correction values for tool 3. [Fig. 12] is an explanatory diagram showing a composite tool error shape obtained by overlaying and synthesizing the first tool error shape and the second tool error shape.

Claims (8)

A processing method of a workpiece, which is carried out by a processing system having a workpiece holding means, a tool holding means and a moving means, the workpiece holding means holds the workpiece, and the tool holding means The means holds a tool for processing the workpiece held by the workpiece holding means, and the moving means moves relative to the workpiece in order to process the workpiece with the tool held by the tool holding means. The workpiece moves the aforementioned tool, This processing method has a first step, a second step and a third step, The first step is to obtain a first error, which is a contour error of the tool obtained from the outer shape of the tool measured by the first measuring device, The second step is to obtain the second error, which is obtained by converting the machining error calculated from the shape of the machined surface of the workpiece measured by the second measuring device into the contour error of the tool, The aforementioned third process is based on the predetermined NC program, and the aforementioned moving means moves the aforementioned tool relative to the aforementioned workpiece, In the third step, the NC program corrects the position of the tool based on a composite error obtained by adding the second error to the first error. The processing method of the processed object as described in claim 1, wherein, The NC program includes an arithmetic expression for calculating the position of the tool, and the NC program uses the arithmetic expression to correct the position of the tool. The processing method of the processed object as described in claim 1, wherein, The first step includes the following processing: measuring the shape of the tool with the first measuring device, and determining a contour error between the measured tool outer shape and the ideal tool outer shape as the first error, The aforementioned second step includes the following processing: measuring the shape of the machined surface of the aforementioned workpiece by the aforementioned second measuring device, and finding a difference between the measured shape of the machined surface of the aforementioned workpiece and the ideal workpiece that can be offset The difference in shape of the machined surface, that is, the tool contour error of the machining error, is the second error mentioned above. The processing method of the processed object as described in claim 3, wherein, The measured measurement points, shape errors, and normal vectors of the measurement points of the machined surface of the machined object are obtained from the shape of the machined surface of the machined object measured by the second measuring device. The aforementioned second error is obtained from the measurement points of the machined surface, the shape error, and the normal vector of the measurement points. The processing method of the processed object as described in claim 3, wherein, The aforementioned first step further includes: extracting the outline shape of the tool including the aforementioned first error as the first tool error shape, The aforementioned second step further includes: extracting the outline shape of the tool including the aforementioned second error as a second tool error shape. The processing method of the processed object as described in claim 5 further has: The fourth step of calculating the correction amount of the NC program based on the combined tool error shape obtained by combining the first tool error shape and the second tool error shape, In the third step, the NC program performs position correction of the tool based on the correction amount. The processing method of the processed object as described in claim 1, wherein, The aforementioned tool is a ball end mill or a fillet end mill used to process the aforementioned workpiece. A processing system for an object to be processed, which is used to implement the processing method for an object to be processed according to any one of claims 1 to 7.

Images