JP4581858B2 - Machine tool controller that reciprocates the tool in synchronization with the rotation of the spindle - Google Patents

Description

  The present invention relates to a control device for a machine tool that processes a workpiece by reciprocating a tool in synchronization with rotation of a main shaft.

  Conventionally, as described in Patent Document 1 below, as a machine tool for machining a workpiece whose center of rotation is eccentric, such as a crank pin or a cam, the feed position of the tool is controlled synchronously with the rotation angle of the spindle. Machine tools are known. For example, in a grinding machine that grinds a crank pin with a grinding wheel, the movement locus of the grinding wheel that contacts the outer shape of the workpiece rotated by the spindle is obtained with respect to the spindle rotation angle, and this movement locus is used as theoretical profile data. According to the theoretical profile data, the grinding wheel is moved to grind the workpiece. After grinding the workpiece, the workpiece outer shape is actually measured to determine the machining error distribution related to the spindle rotation angle, and the theoretical profile data is corrected based on this machining error distribution. Based on the profile data, the feed amount of the grinding wheel is controlled.

Japanese Patent No. 3120597

  However, as the grinding wheel wears as the machining progresses, the grinding wheel diameter changes, so the theoretical profile data is recalculated, but the above machining error distribution is only measured once as long as the same type of workpiece is machined. It is. The servo motor has a ripple that changes depending on the position of the grinding wheel, and the mechanical friction changes depending on the position of the feed shaft of the grinding wheel. Therefore, the processing error distribution changes. For this reason, in the method of measuring a machining error distribution by measuring the machining shape described above and correcting the theoretical profile data based on the machining error distribution, due to the progress of wear of a tool such as a grinding wheel, There is a problem that the finishing accuracy is lowered.

  On the other hand, every time the grinding wheel diameter changes, if you measure the finished shape of the workpiece, measure the machining error distribution, and correct the theoretical profile data, you must frequently measure the machining error distribution. This is a problem in manufacturing efficiency.

  Accordingly, the present invention has been made to solve the above-described problems, and its purpose is to provide a machining error component that depends on the amount of wear of the tool, that is, the position of the moving range of the tool, and machining that does not depend on the machining error component. By managing the machining error distribution separately into error components, only the machining error component depending on it is obtained according to tool wear, and the command profile data is found accordingly. Improvement of processing and improvement of processing efficiency.

In order to solve the above problems, the following means are effective.
According to a first aspect of the present invention, in a control device for a machine tool that rotates a workpiece about a main shaft and controls feed of the tool in synchronization with the rotation of the main shaft, the amount of wear measured as a relative wear width of the tool is Theoretically, this wear amount is initialized to the initial value every time a predetermined value is exceeded, and the theoretical profile data that defines the feed amount of the tool relative to the spindle rotation angle is calculated based on the finished shape of the workpiece and the wear amount of the tool Each time the theoretical profile data is calculated by the profile data calculation means and the theoretical profile data calculation means, an idle operation or a spark-out operation is performed based on the theoretical profile data, and the actual tool value with respect to the command value at the time of the operation is calculated. A first machining error distribution calculating means for obtaining a position following deviation as a first machining error distribution with respect to the spindle rotation angle; Each time is set, first correction profile data calculating means for correcting the theoretical profile data based on the first processing error distribution to obtain the first correction profile data, and whenever the first correction profile data is calculated, A workpiece is machined with the first correction profile data, the shape of the machined workpiece is measured, and a second machining error distribution with respect to the spindle rotation angle of the machining error with respect to the previous first correction profile data is obtained. Each time the machining error distribution calculating means and the first machining error distribution or the second machining error distribution change, the theory is based on the total machining error distribution which is the sum of the first machining error distribution and the second machining error distribution. A command program that obtains command profile data that corrects the profile data and regulates the feed amount of the tool relative to the spindle rotation angle when machining the workpiece. File data calculation means, and when the first machining error distribution and the second machining error distribution do not change, based on the command profile data already calculated by the command profile data calculation means, Machine tool control characterized in that when the machining error distribution or the second machining error distribution changes, the machine tool is controlled based on the command profile data newly calculated by the command profile data calculation means. Device.

  In the present invention and the following inventions, the workpiece is, for example, a crank pin, a cam, or the like that exists at a position where the main shaft is eccentric with respect to the workpiece. In addition, the machining is not particularly limited, but in general, it is a numerically controlled grinding machine using a grinding wheel whose feed amount is synchronously controlled in synchronization with the spindle rotation angle. As long as it is controlled synchronously, it can be applied to machine tools using other tools. In short, the present invention can be applied to a machine tool in which the tool feed amount is synchronously controlled with respect to the spindle rotation angle, and the tool movement range changes as the tool wears.

  The total machining error distribution is an error distribution related to the spindle rotation angle with respect to the theoretical shape of the finished shape of the workpiece. The first machining error distribution is an error distribution that occurs even in a substantially no-load state (idle operation or spark-out). Since the first machining error distribution changes depending on the ripple of the servo motor and the machine friction of the tool feed shaft, the first machining error distribution is an error distribution that changes depending on the tool movement range, that is, the wear amount of the tool. The second machining error distribution is an error distribution that varies depending on the machining load, varies depending on the material (rigidity) of the workpiece and the type of tool, and is a machining error distribution that does not vary depending on the movement range of the tool. .

The present invention is characterized in that the total machining error distribution is divided into two components, a first machining error distribution and a second machining error distribution. Then, the first machining error distribution is measured and added to the second machining error distribution assumed to be kept constant, thereby obtaining a total machining error distribution, and theoretical profile data based on the total machining error distribution. Is characterized in that command profile data for actually commanding the feed amount of the tool is obtained. With such a configuration, even if the movement range of the tool changes, the error is accurately corrected, so that the machining accuracy is improved.
The first machining error distribution may be measured at any timing, whether measured every time the wear amount of the tool exceeds a predetermined value, measured at a predetermined time interval, or measured every predetermined number of times of grinding. is there. Furthermore, the total machining error distribution is obtained by measuring the finished shape of the workpiece. The first machining error distribution can be obtained by measuring the tracking delay deviation of the servo system as an example. The second machining error distribution may be measured directly, or may be obtained by subtracting the first machining error distribution from the total machining error distribution. In the machining period in which the machining load does not change, the machining error changes in the first machining error distribution. Therefore, every time the amount of tool wear exceeds a predetermined value, the amount of change in the first machining error distribution is obtained. The total machining error distribution may be corrected according to the amount of change. Further, even if the previous command profile data is corrected directly according to the amount of change, it is equivalent to correcting the theoretical profile data with the corrected total machining error distribution, and is included in the scope of this claim. It is.

  The first machining error distribution is a distribution that changes according to the position of the tool movement range. For example, if the shape or material of the workpiece does not change, the processing load is considered to be constant, so that only the first processing error distribution changes according to the wear of the tool. Therefore, by measuring the first machining error distribution and obtaining the command profile data according to the distribution, it is possible to prevent the machining accuracy from being lowered even if the tool is worn. The first machining error distribution may be measured at any timing, whether measured every time the wear amount of the tool exceeds a predetermined value, measured at a predetermined time interval, or measured every predetermined number of times of grinding. is there.

  The second machining error distribution is a component that does not change depending on the position where the tool moves. The feature is that the machining error is measured by measuring the outer shape of the workpiece machined from the second machining error distribution based on the first correction profile data. Then, in a period in which machining conditions such as machining load do not change, the second machining error distribution is assumed to be unchanged, and the first machining error distribution is obtained every time the wear amount of the tool exceeds a predetermined value, and the total machining error is obtained. The feature is that the command profile data is obtained based on the distribution. That is, the command profile data is corrected according to the first machining error distribution measured at an arbitrary timing, for example, every time the wear amount of the tool exceeds a predetermined value.

According to a second aspect of the present invention, there is provided a control device for a machine tool in which a workpiece is rotated around a main shaft and a tool is fed and controlled in synchronization with the rotation of the main shaft, and the amount of wear measured as a relative wear width of the tool is Theoretically, this wear amount is initialized to the initial value every time a predetermined value is exceeded, and the theoretical profile data that defines the feed amount of the tool relative to the spindle rotation angle is calculated based on the finished shape of the workpiece and the wear amount of the tool Each time the theoretical profile data is calculated by the profile data calculating means and the theoretical profile data calculating means, the idle operation or the spark-out operation is performed based on the theoretical profile data, and the actual position of the tool with respect to the command value during this operation A first machining error distribution calculating means for obtaining the following deviation as a first machining error distribution with respect to the spindle rotation angle, and a new machining condition Each time the workpiece is machined using the theoretical profile data, the shape of the machined workpiece is measured, and the total machining error distribution for the spindle rotation angle of the machining error relative to the theoretical profile data is calculated. A machining error distribution computing means, a second machining error distribution computing means for obtaining a distribution obtained by subtracting the first machining error distribution from the total machining error distribution every time the total machining error distribution is computed, Whenever one machining error distribution or the second machining error distribution changes, the theoretical profile data is corrected based on the total machining error distribution which is the sum of the first machining error distribution and the second machining error distribution, Command profile data calculation means for obtaining command profile data that defines a feed amount of the tool with respect to the spindle rotation angle when machining an object, and a first machining error distribution, and 2 When the machining error distribution does not change, based on the command profile data already calculated by the command profile data calculation means, and when the first machining error distribution or the second machining error distribution changes, A machine tool control apparatus that controls a machine tool based on command profile data newly calculated by command profile data calculation means.

  The method for obtaining the second machining error distribution is different from that of the first aspect of the invention. In this claim, the machining shape is measured, and the total machining error distribution with respect to the theoretical profile data is measured. The second machining error distribution is obtained as a distribution obtained by subtracting the first machining error distribution from the total machining error distribution. During a period when the machining load is constant, the second machining error distribution is assumed to be constant, the first machining error distribution is measured according to the amount of tool wear, and the total machining error distribution reflecting the first machining error distribution is measured. According to this, the command profile data is calculated.

According to a third aspect of the present invention, the command profile data calculating means is configured to determine the command profile data based on a deviation distribution of the tracking deviation distribution with respect to the previous tracking deviation distribution and a deviation of theoretical profile data that changes in accordance with the amount of tool wear. This is a machine tool control device characterized in that it is a means for correcting based on the above.
That is, when machining a certain type of workpiece, once the total machining error distribution is measured and command profile data is obtained, only the change amount of the first machining error distribution and the change amount of the theoretical profile data are obtained. Even if the previous command profile data is corrected, as a result, the same results as in claims 1 and 2 can be obtained.

  According to the first and second aspects of the invention, idle operation or spark-out operation is performed based on the theoretical profile data, and the following deviation of the actual position of the tool with respect to the command value at the time of this operation is expressed as the first machining error distribution with respect to the spindle rotation angle Since the command profile data is obtained based on the first machining error distribution, even if the position where the tool moves is changed, the machining error is corrected based on the change. That is, an error in the feed amount depending on the position where the tool movement range exists, which is caused by the servo motor ripple and the mechanical friction of the tool feed shaft, is corrected. Therefore, even if the wear of the tool progresses, it becomes possible to perform highly accurate processing.

  In the invention of claim 1, the second machining error distribution is obtained from measurement of the finished shape of the workpiece, and in the invention of claim 2, the total machining error distribution is obtained from measurement of the finished shape of the workpiece. . In any of the inventions, as the wear of the tool progresses, the position of the movement range of the tool changes. The first machining error distribution depending on this change is measured, and based on the first machining error distribution. Since the command profile data is corrected, even if the existing position of the tool movement range changes, the machining error is corrected based on the change. That is, an error in the feed amount depending on the position where the tool movement range exists, which is caused by the servo motor ripple and the mechanical friction of the tool feed shaft, is corrected. Therefore, even if the wear of the tool progresses, it becomes possible to perform highly accurate processing.

  The invention of claim 3 corrects the command profile data based on the deviation distribution of the tracking deviation distribution with respect to the previous tracking deviation distribution and the deviation of the theoretical profile data that changes in accordance with the wear amount of the tool. Yes. That is, the previous command profile data is corrected by the difference distribution of the first machining error distribution, and, as in claims 1 and 2, even if the existing position of the tool movement range changes, it is based on the change. Processing error is corrected. That is, an error in the feed amount depending on the position where the tool movement range exists, which is caused by the servo motor ripple and the mechanical friction of the tool feed shaft, is corrected. Therefore, even if the wear of the tool progresses, it becomes possible to perform highly accurate processing.

Hereinafter, the present invention will be described based on specific examples.
However, the embodiments of the present invention are not limited to the following examples.

FIG. 1 is a hardware configuration diagram of a grinding machine 100 according to the present embodiment. In this embodiment, a right-handed orthogonal coordinate system is used in which the upward direction in the vertical direction is the positive direction in the y-axis direction. Therefore, the XZ plane is a horizontal plane. The origin of the X axis is taken as the main axis line.
On the bed 36 of the grinding machine 100 installed on a horizontal floor surface, a table 40 that moves in the Z-axis direction by driving the motor 24 is provided.

  The rotation amounts of the motors 24 and 28 are detected by the encoders 22 and 26, respectively. The table 40 is provided with a headstock 30 having a main shaft 31 and a tailstock 42 having a center 38, and a center 38 of the tailstock 42 and a chuck 32 provided at the tip of the main shaft 31 are used for machining. An object W is rotatably attached with the center of the main shaft as a rotation axis (C axis). The main shaft 31 rotates the workpiece W via the chuck 32 by driving the motor 28.

  On the bed 36, a grindstone base 48 that moves in the X-axis direction by driving of a motor 54 is provided. The amount of rotation of the motor 54 is detected by the encoder 52. A grinding wheel 44 is provided on the side surface of the grinding wheel base 48, and the grinding wheel 46 (tool) disposed over the circumference of the grinding wheel 44 is rotated by driving the motor 50. A sizing device 70 is provided on the bed 36 so as to face the grinding wheel 44. The sizing device 70 moves in the X-axis direction and is used for measuring the outer diameter of the cylindrical portion of the workpiece W.

The numerical controller 10 includes a memory 1 (storage means), a CPU 2 (calculation means), and interfaces (I / F) 3 and 4. The I / F 3 mediates data transmission / reception between the CPU 2 and the input / output device 12 including a keyboard and a display.
The I / F 3 mediates transmission / reception of data to / from the PLC 14, the amplifier 16, the grinding wheel head moving motor driving circuit 18, the table moving motor driving circuit 19, and the spindle motor driving circuit 20. The programmable logic controller (PLC) 14 controls the sizing device 70. The amplifier 16 amplifies the output of the sizing device 70 and performs A / D conversion.

  The wheel head moving motor drive circuit 18, the table moving motor drive circuit 19, and the spindle motor drive circuit 20 amplify or servo-control each drive signal of the X axis, Z axis, and C axis (rotary axis). These drive circuits may be constituted by a servo control device incorporating a CPU.

  In this way, the grinding machine 100 is configured, and an eccentric cylinder is obtained by accurately synchronizing the rotational movement around the C-axis (main axis) and the parallel movement of the grinding wheel head in the X-axis direction perpendicular to the C-axis. Eccentric cylindrical grinding of the pin (workpiece W) is performed.

Next, the processing procedure of the CPU 2 of the numerical controller 10 will be described with reference to FIG.
In step 100, theoretical profile data is computed. This is because the position coordinate X of the grindstone 46 that makes the grindstone 46 come into contact with the work piece when the finished-shaped work piece whose center of rotation is eccentric is rotated around the main spindle. Obtained as a variable. Hereinafter, the relationship A (θ) between the spindle rotation angle θ and the X coordinate of the grindstone 46 at this time is referred to as theoretical profile data. However, the negative direction of the X coordinate is the cutting direction, and the larger the X coordinate is in the positive direction, the larger the diameter of the workpiece at the grinding point.

  Next, in step 102, the grindstone 46 is idled according to the theoretical profile data A (θ). Next, in step 104, the relationship between the actual position X of the grindstone 46 from the output of the encoder 52 and the spindle rotation angle θ from the output of the encoder 26 (hereinafter this relationship is indicated by B (θ)) is obtained. Next, in step 106, the deviation Δ1 (θ) with respect to the theoretical profile data A (θ) of the actual position B (θ) is calculated by Δ1 (θ) = B (θ) −A (θ). Next, in step 108, the first correction profile data C (θ) is calculated by C (θ) = A (θ) −Δ1 (θ). That is, when the actual position B (θ) of the grinding wheel is larger than the theoretical position, the diameter of the workpiece becomes large. Therefore, the theoretical value A (θ) is subtracted and corrected by the error Δ1 (θ). Thus, it is necessary to obtain the first correction profile data. The correction relationship at this time is shown in FIG.

  Next, in step 110, the workpiece is machined with the first correction profile data C (θ). Next, in step 112, the outer shape of the machined workpiece is measured, and the outer shape is input. Similarly to the case of obtaining the theoretical profile data, the X coordinate of the grindstone 46 that is in contact with the outer shape is obtained with respect to the main shaft rotation angle θ from the geometric consideration, so that the grindstone 46 corresponding to the outer shape can be obtained. Actual profile data D (θ) converted to the X coordinate is obtained.

  Next, in step 114, the second machining error distribution Δ2 (θ), which is the deviation of the actual profile data D (θ) from the first correction profile data C (θ), is Δ2 (θ) = D (θ) −C. It is obtained by (θ). Next, in step 116, the total machining error distribution Δ (θ) is calculated by Δ1 (θ) + Δ2 (θ). Next, in step 118, the command profile data E (θ) is obtained by A (θ) −Δ (θ). That is, the fact that the total machining error distribution Δ (θ) is large means that the actual position of the grindstone 46 has advanced in the positive direction of the X axis relative to the position of the grindstone 46 that obtains the theoretical shape. Therefore, by subtracting and correcting the theoretical profile data A (θ) by the total machining error distribution Δ (θ), command profile data E (θ) is obtained, and processing is performed using the command profile data E (θ). It is necessary to set the actual position of the actual grindstone 46 to the position given by the theoretical profile data A (θ). The relationship of each quantity at this time is shown in FIG.

  Next, in step 120, the workpiece is machined using the command profile data E (θ) while actually controlling the X coordinate of the grindstone 46 synchronously with the spindle rotation angle θ. Next, in step 122, it is determined whether or not the grinding wheel wear amount h has exceeded a predetermined value Th. The grinding wheel wear amount h can be obtained by actually measuring the tip position of the grinding wheel 46. If the grindstone wear amount h exceeds the predetermined value Th, the grindstone diameter is changed after the grindstone wear amount h is initially set to 0 in step 124. From the grindstone diameter and the finished shape of the workpiece, Similar to step 100, theoretical profile data A (θ) is calculated. Next, in step 126, similarly to step 102, the feed amount of the grindstone 46 is synchronously controlled based on the theoretical profile data A (θ). Next, in step 128, as in step 104, the actual position X and the spindle rotation angle θ are input from the encoders 52 and 26, and their relationship B (θ) is obtained. Next, in step 130, as in step 106, the first processing error distribution Δ1 (θ) is obtained by B (θ) −A (θ).

  Next, in step 132, it is determined whether or not the machining conditions such as the rigidity of the workpiece have changed. If the machining conditions have not changed, in step 134, the total machining error distribution Δ (θ) is the first machining. It is obtained by the sum of the error distribution Δ1 (θ) and the second processing error distribution Δ2 (θ). At this time, assuming that the second machining error distribution Δ2 (θ) has not changed, the values used up to the previous time are used as they are. Next, in step 136, as in step 118, the command profile data E (θ) is calculated from A (θ) −Δ (θ).

  Next, the process proceeds to step 138, where it is determined whether or not all machining has been completed. If all machining has been completed, this program is terminated. If all machining has not been completed, the process returns to step 120, and machining of the workpiece is executed based on the command profile data E (θ) thus obtained. Step 122 and the subsequent steps are repeatedly executed.

  By repeating the steps 120 to 138, every time the grinding wheel wear amount h exceeds the predetermined value Th, the theoretical profile data A (θ) is recalculated, and profile data indicating the actual position of the grinding wheel by idling. B (θ) is measured from the encoders 52 and 26, the total machining error distribution Δ (θ) is calculated, the command profile data E (θ) is calculated, and machining based on the command profile data E (θ) is calculated. Is executed. Therefore, even if the position of the grinding wheel on the X axis in the reciprocating range of the grinding wheel changes due to wear of the grinding wheel, the command profile data E that is a result of correcting the machining error distribution Δ1 (θ) based on this change. Processing based on (θ) will be performed, and this error component will be removed from the finished shape of the workpiece, thereby improving processing accuracy.

  On the other hand, if it is determined in step 132 that the machining conditions have changed, this means that the second machining error distribution Δ2 (θ) also changes, and thus the processing is repeated from step 108. That is, the second machining error distribution Δ2 (θ) is measured, and the command profile data E (θ) obtained by correcting the theoretical profile data A (θ) is calculated in consideration of the second machining error distribution Δ2 (θ). Based on this, the workpiece is processed. Therefore, even when the machining conditions change due to changes in the rigidity of the workpiece, machining with a compensated machining error distribution is executed.

  In step 124, when the grinding wheel wear amount exceeds a predetermined value, the theoretical profile data A (θ) is calculated to obtain the first processing error distribution Δ1 (θ). The theoretical profile data The calculation of A (θ) may be performed when the grinding wheel wear amount exceeds a value smaller than the low value at this time. In this case, the command profile data E (θ) is calculated by A (θ) −Δ (θ). However, the total machining error distribution Δ (θ) is calculated as not changing.

  In steps 102 and 126, the grindstone is idly operated with the theoretical profile data A (θ), and the actual profile data B (θ) is acquired. However, the encoders 52 and 26 are used at the time of sparking out during the finishing of the workpiece. The X coordinate and the spindle rotation angle θ may be acquired from B to obtain B (θ).

  The processing procedure of the CPU 2 in this embodiment is shown in FIG. The difference from the first embodiment is how to obtain the second machining error distribution Δ2 (θ) and the total machining error distribution Δ (θ). Steps 200 to 206 are the same as steps 100 to 106 in FIG. In step 208, the workpiece is actually machined based on the theoretical profile data A (θ). In step 210, the shape of the machined workpiece is input, and the corresponding actual profile data F (θ) is calculated. The This calculation is the same as the calculation method in step 112 in FIG. Next, in step 212, the total machining error distribution Δ (θ) is calculated by F (θ) −A (θ). That is, the deviation of the actual profile data F (θ) obtained by measuring the outer shape of the workpiece with respect to the theoretical profile data A (θ) gives the total machining error distribution Δ (θ). Next, in step 214, the second machining error distribution Δ2 (θ) is calculated by Δ (θ) −Δ1 (θ). In this way, the first processing error distribution Δ1 (θ) and the second processing error distribution Δ2 (θ) may be obtained.

  Processing steps 218 to 238 after the first machining error distribution Δ1 (θ) and the second machining error distribution Δ2 (θ) are obtained are exactly the same as steps 118 to 138 in FIG. In this way, command profile data can be obtained.

The total machining error distribution Δ (θ) is obtained by the method of the first embodiment or the second embodiment, and the command profile data E (θ) is obtained. Steps 118 and 218 are executed in the same manner as in the first or second embodiment. When the grinding wheel wear amount h exceeds a predetermined value Th, the first processing error distribution Δ1 (θ) is obtained in the same manner as in the first and second embodiments. Then, a deviation δ1 (θ) of the newly obtained first machining error distribution Δ1 _new (θ) with respect to the previously obtained first machining error distribution Δ1 _old (θ) is calculated. Then, the current command profile data E _new (θ) is obtained from the command profile data E _old (θ) + δA (θ) −δ1 (θ). However, δA (θ) = A _new (θ) −A _old (θ), A _new (θ) is the current theoretical profile data, and A _old (θ) is the previous theoretical profile data. The command profile data E _old (θ) is the previous command profile data.

That is,
E _new (θ) = A _new (θ) −Δ _new (θ)
E _old (θ) = A _old (θ) −Δ _old (θ)
Therefore,
E _new (θ) −E _old (θ) = A _new (θ) −A _old (θ) − {Δ _new (θ) −Δ _old (θ)}
Since Δ2 (θ) does not change,
Δ _new (θ) −Δ _old (θ) = Δ 1 _new (θ) −Δ 1 _old (θ) = δ 1 (θ)
It is.
Therefore,
E _new (θ) −E _old (θ) = δA (θ) −δ1 (θ)
And
E _new (θ) = E _old (θ) + δA (θ) −δ1 (θ)
Calculated with

  Therefore, the command profile data E (θ) can be obtained also in the third embodiment.

  The theoretical profile data calculation means of claim 3 is realized by the CPU 2, the memory 1, and the processing functions of steps 100 and 124 described above. The first processing error distribution calculation means is realized by the CPU 2, the memory 1, and the processing functions of the above steps 102, 104, 106, 126, 128, and 130. The first correction profile data calculation means is realized by the CPU 2, the memory 1, and the functional processing in step 108. The second machining error distribution calculation means of claim 4 is realized by the CPU 2, the memory 1, and the processing functions of the above steps 110, 112, and 114. The command profile data calculation means of claim 4 is realized by the CPU 2, the memory 1, and the processing functions of the above steps 116, 118, 134, 136.

  The total machining error distribution calculating means of claim 5 is realized by the CPU 2, the memory 1, and the processing functions of the above steps 208, 210 and 212. Further, the second machining error distribution calculating means according to claim 5 is realized by the CPU 2, the memory 1, and the processing function of step 214. The command profile data calculation means of claim 5 is realized by the CPU 2, the memory 1, and the processing functions of the above steps 218, 234 and 236.

The command profile data calculation means of claim 3 is realized by the command profile data calculation function in the first to third embodiments. However, since the third aspect is characterized in that the first machining error distribution is obtained and the command command profile data is calculated based on the first machining error distribution, the method other than the first to third embodiments is also included. It is a waste.

  The method invention is realized by the apparatus of the above-described embodiment.

  INDUSTRIAL APPLICABILITY The present invention is effective for an apparatus for machining a workpiece having a rotational axis such as a crank pin or a cam that is eccentric.

The block diagram of the grinding machine which has the numerical control apparatus which concerns on one specific Example of this invention. The flowchart which showed the process sequence by the numerical control apparatus which concerns on Example 1 of this invention. The flowchart which showed the process sequence by the numerical control apparatus which concerns on Example 1 of this invention. Explanatory drawing explaining the correction method of the command profile data by the numerical control apparatus which concerns on Example 1 of this invention. The flowchart which showed the process sequence by the numerical control apparatus which concerns on Example 2 of this invention. The flowchart which showed the process sequence by the numerical control apparatus which concerns on Example 2 of this invention.

DESCRIPTION OF SYMBOLS 10 ... Numerical control apparatus 44 ... Grinding wheel 46 ... Grinding wheel 28, 54 ... Motor 26, 52 ... Encoder 31 ... Spindle

Claims (3)

In a machine tool control device that rotates a workpiece around a spindle and feeds a tool in synchronization with the rotation of the spindle,
Each time the amount of wear measured as the relative wear width of the tool exceeds a predetermined value, this wear amount is initialized to an initial value, and the spindle rotation angle is determined based on the finished shape of the workpiece and the wear amount of the tool. Theoretical profile data calculation means for calculating theoretical profile data that defines the feed amount of the tool with respect to
Each time the theoretical profile data is calculated by the theoretical profile data calculating means, idle operation or spark-out operation is performed based on the theoretical profile data, and the tracking deviation of the actual position of the tool with respect to the command value at the time of this operation is calculated. A first machining error distribution calculating means for obtaining a first machining error distribution with respect to the spindle rotation angle;
First correction profile data calculating means for correcting the theoretical profile data based on the first processing error distribution to obtain first correction profile data each time a new processing condition is set;
Each time the first correction profile data is calculated, a workpiece is machined with the first correction profile data, the shape of the machined workpiece is measured, and a machining error relative to the first correction profile data is measured. A second machining error distribution calculating means for obtaining a second machining error distribution with respect to the spindle rotation angle;
Each time the first machining error distribution or the second machining error distribution changes, the theoretical profile data is based on the total machining error distribution that is the sum of the first machining error distribution and the second machining error distribution. And command profile data calculation means for obtaining command profile data that defines the feed amount of the tool with respect to the spindle rotation angle when machining the workpiece,
When the first machining error distribution and the second machining error distribution do not change, based on the command profile data already calculated by the command profile data calculation means, the first machining error distribution, or When the second machining error distribution changes, the machine tool control device controls the machine tool based on the command profile data newly calculated by the command profile data calculation means. In a machine tool control device that rotates a workpiece around a spindle and feeds a tool in synchronization with the rotation of the spindle,
Each time the amount of wear measured as the relative wear width of the tool exceeds a predetermined value, this wear amount is initialized to an initial value, and the spindle rotation angle is determined based on the finished shape of the workpiece and the wear amount of the tool. Theoretical profile data calculation means for calculating theoretical profile data that defines the feed amount of the tool with respect to
Each time the theoretical profile data is calculated by the theoretical profile data calculating means, idle operation or spark-out operation is performed based on the theoretical profile data, and the tracking deviation of the actual position of the tool with respect to the command value at the time of this operation is calculated. A first machining error distribution calculating means for obtaining a first machining error distribution with respect to the spindle rotation angle;
Each time a new machining condition is set, the workpiece is machined using the theoretical profile data, the shape of the machined workpiece is measured, and the machining error relative to the theoretical profile data with respect to the spindle rotation angle is measured. A total machining error distribution calculating means for obtaining a total machining error distribution;
A second machining error distribution calculating means for obtaining a distribution obtained by subtracting the first machining error distribution from the total machining error distribution every time the total machining error distribution is calculated;
Each time the first machining error distribution or the second machining error distribution changes, the theoretical profile data is based on the total machining error distribution that is the sum of the first machining error distribution and the second machining error distribution. And command profile data calculation means for obtaining command profile data that defines the feed amount of the tool with respect to the spindle rotation angle when machining the workpiece,
When the first machining error distribution and the second machining error distribution do not change, based on the command profile data already calculated by the command profile data calculation means, the first machining error distribution, or When the second machining error distribution changes, the machine tool control device controls the machine tool based on the command profile data newly calculated by the command profile data calculation means.   The command profile data calculation means corrects the command profile data based on a deviation distribution of the follow-up deviation distribution with respect to a previous follow-up deviation distribution and a deviation of theoretical profile data that changes according to the amount of tool wear. The machine tool control device according to claim 1, wherein the control device is a machine tool control device.

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