JP3122484B2 - Copy control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying control device,
In particular, the present invention relates to a control device for changing a cutter path at a corner when a tracer head follows a model prior to machining by a cutter.

[0002]

2. Description of the Related Art In a conventional copying control apparatus, copying control has been performed on the assumption that a cutter (tool) axis of a copying machine tool is mechanically integrated with a tracer head. That is, the copying control device detects the displacement amount of each axis applied to the stylus by the tracer head, and calculates the speed command of each axis in the copying operation circuit using this displacement amount. Then, the motor of each axis is driven by the speed command to move the cutter relatively to the work, and the tracer head is moved at the same speed along the model surface. By repeating these operations, control is performed so that the workpiece is machined in the same shape as the model.

As described above, in the case where a tool such as a cutter and a workpiece are relatively moved by a conventional speed control value according to a speed command value, the tracer head and the tool are simultaneously simultaneously driven by a formed feed shaft drive command. It was driven, and in particular, did not have the function of leading the tracer head to the cutter axis.

[0004]

However, when the model is modeled with a stylus provided at the tip of the tracer head,
When the stylus collides with the corner of the model or the like, it is equivalent to a state where the tracer head temporarily bites into the model. This is because the tracer head tends to go too far due to the delay of the servo system constituting the drive unit of the tracer head, the influence of the inertia of the machine, and the like.

As a result, the cutter bites into the work by the same amount as the tracer head, and the machining accuracy at the corner decreases. Accordingly, the inventor has previously proposed and filed an application for a control device capable of delaying a tool with respect to a tracer head by a predetermined time and following the same path (see reference number FAP1).
121, submission date February 5, 1991).

According to the above proposal, an auxiliary shaft for driving the tracer head is provided so as to be superimposed on each feed shaft on each axis of the machine tool, and this auxiliary shaft is controlled by auxiliary shaft control means, and the tracer head is attached to the tool. Let the model precede it. As a result, it is possible to detect biting of the tracer head at a sudden change in shape such as a corner portion of the model, and to prevent biting at the corner portion in profiling with a tool.

[0007] The control device proposed above can detect a sudden change in the shape, but if the cutter simply follows the tracer head path with a certain delay,
Biting cannot be prevented, and when biting occurs, movement of the cutter must be forcibly stopped. Alternatively, in order to perform continuous contour machining with a tool, it is necessary to change the tool path at a sudden change in the shape of the model, which causes a reduction in machining accuracy. The present invention has been made in view of such a point, and while the tool is delayed with respect to the tracer head for a certain period of time, the correction command according to the displacement of the following axis is always formed to prevent the tool from biting into the workpiece. It is an object of the present invention to provide a control device that can be reliably avoided.

[0008]

According to the present invention, in order to solve the above-mentioned problems, the displacement position detected by the tracer head is calculated to obtain a following speed command value for each feed axis. in If There controller forming a by Rioku Ri axis drive command, to control the auxiliary shaft provided superposed on the feed shaft, relatively moves the tracer head relative to the model in parallel with the feed shaft auxiliary Axis control means, correction operation means for determining a correction command value for the feed axis drive command by multiplying a displacement amount received by the tracer head for each feed axis by a predetermined correction gain, and correcting the following speed command value Means for correcting based on command value
And the corrected speed command value is delayed for a predetermined time.
A delay unit that outputs the feed shaft drive command, and subtracts the value of the feed shaft drive command output delayed with the delay unit from the profile speed command value, to obtain a speed command value to the auxiliary axis control unit. And a subtraction means for outputting.

[0009]

The tracer head has an auxiliary axis superimposed on the feed axis for each axis of the tool, and the tracer head is controlled by the auxiliary axis control means. Therefore, the tracer head is driven independently of the tool axis. You. The correction calculating means determines a correction command value for the feed axis drive command by multiplying a displacement amount received by the tracer head by a predetermined correction gain for each feed axis. Tracing speed command value is temporarily after being corrected based on the corrected command value is stored in the slow Nobete stage, is output delayed by a predetermined time with respect to each axis of the machine tool. The auxiliary axis control means is provided with a speed command value obtained by subtracting the feed axis driving command from the following speed command value. As a result, the tracer head is moved ahead of the tool axis to model the model, and the tool is controlled by a corrected path command different from the path of the tracer head to the model, thereby preventing biting. Can be.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing main control elements of the copying control device. In the figure, only the configuration of the portion corresponding to the X-axis among the three axes for controlling the tool tracing is shown,
For example, a control element for the Y axis or the Z axis is similarly configured.

The X-axis tracing speed command value Vx is obtained at a constant calculation cycle by tracing the displacement detected by the tracer head. The following speed command value Vx is input to the FIFO memory 1 via the synthesizing circuit 2 as a feed axis drive command. The FIFO memory 1 is a so-called first-in first-out delay storage unit having a delay buffer function.

The tracking speed command value Vx is stored as a plurality of feed axis drive command data in the order of input to the FIFO memory 1, and is output in order from the first input data when the storage capacity overflows. Therefore, the copying speed command value Vx is stored in the FIFO memory 1 for a certain period of time, so that the X-axis driving command VxB delayed by the required time is used as the X-axis main motor (Xm) 36.
Is output to The delay time of the FIFO memory 1 can be freely set by an external delay time setting signal or the like in accordance with the distance that the tracer head should precede the tool.

[0013] The following speed command value Vx is further input to the subtraction circuit 3 as an addition signal. This subtraction circuit 3
Then, from the following speed command value Vx, the FIFO memory 1
, The X-axis drive command VxB output with a delay is subtracted. The result of the subtraction by the subtraction circuit 3 is further corrected by the correction operation circuit 4 and output as a speed command value to the X-axis submotor (Xs) 37.

By the way, a correction command value VxC is input to the synthesizing circuit 2 from a correction operation circuit 5 in addition to the following speed command value Vx. The correction operation circuit 5 calculates the correction command value Vx
C is calculated from a displacement εxi of the X-axis generated when the tracer head is pressed against the model by a predetermined calculation cycle (i, i +
1, i + 2,...). The tracing speed command value Vx is synthesized by the synthesizing circuit 2 with the correction command value VxC commanded from the correction operation circuit 5, and is input to the FIFO memory 1 as the X-axis drive command VxB.

In the correction operation circuit 5, the correction gain G is determined according to the bite amount of the tracer head and the diameter of a tool for processing a work, and is set from outside. Further, the displacement amount εxi received by the tracer head is input every predetermined calculation time s, and the correction command value VxCi is sequentially calculated from the following equation. VxCi = εxi × G / s (1)

Since the correction command value is determined for each predetermined calculation cycle in accordance with the amount of displacement received by the tracer head, a corrected path is always instructed to the tool. Therefore,
When the tracer head detects a sudden change in shape, the main motor 36 not only controls the tool to follow the path of the tracer head with a delay by a certain amount, but also adjusts the correction command value VxC to prevent biting. After the determination, it is possible to perform continuous copying while avoiding biting of the tool into the work. The correction operation circuit 5 determines the correction command value VxCi according to the difference between the displacement vector εx, εy, εz for each axis of the tracer head and the reference displacement at each predetermined calculation cycle, and combines it with the synthesis circuit 2. The speed command value Vx may be combined with the large speed command value Vx.

Further, the tracer head temporarily differs from the moving locus of the cutter, for example, because the X-axis drive command VxB fluctuates from the speed command value Vx due to the correction command value VxC. Therefore, for example, a signal for correcting the speed command value to the X-axis submotor 37 is formed based on the distance (actual leading amount La) where the tracer head actually leads the tool, and the correction arithmetic circuit 4 To be entered.

Regarding this point, a configuration corresponding to the correction of the leading amount in FIG. 1 will be further described. Arithmetic circuit 6
Subtracts the X-axis drive command VxB delayed by the FIFO memory 1 from the following speed command value Vx, and corresponds to the arithmetic circuit 3. The result of the subtraction is input to the register circuit 7 as a command leading amount (theoretical leading amount) L after the speed command is converted into a position command. The data stored in the register circuit 7 indicates the current value of the command advance amount L instructed from the trace control unit to the tracer head which should precede the cutter movement. On the other hand, the actual leading amount La of the tracer head is stored in the register circuit 8 as a feedback signal fed back from the sub motor for each axis.
Is stored in The outputs of these two register circuits 7 and 8 are compared in an arithmetic circuit 9. That is, the arithmetic circuit 9
, A command leading amount L is input as a subtraction signal, and an actual leading amount La is input as an addition signal. Here, a correction signal of the X-axis submotor is calculated as a difference between these L and La. The output of the arithmetic circuit 9 is multiplied by a predetermined gain G ₁ in a constant circuit 10 to be a subtraction signal of the arithmetic circuit 4 for correction.

As described above, when the distributed speed command values Vx and the like of the respective axes that have been distributed are output to the cutter side, the FIFO is used.
The feed axis drive command is delayed from the memory 1 by a necessary time and output to the main motor 36. The relative movement between the tracer head and the model is controlled by a sub motor 37 which is superimposed on the movement of the main motor 36 and controlled equivalently to the copying speed command value Vx. Thus, the model can be modeled with the tracer head preceding the tool axis, and the tool can be controlled by a corrected path command that is different from the path of the tracer head to the model.

Further, in the following control apparatus of the present invention, the feedback control is applied to the leading amount of each axis so that the actual leading amount La always matches the command leading amount L. Of the cutter, the trajectory of the cutter is always controlled by the tracer head on a path whose displacement is corrected.

FIG. 2 shows an example of the relationship between the cutter path, the path of the tracer head, and the correction speed on the XZ plane. Now, the tracing speed command Vx,
Vz allows the tracer heads to move the velocity vectors V ₁ , V
₂ and V ₃ , it is assumed that the user moves from the coordinate point Pt and the bite amount increases in the suddenly changing shape of the model. From equation (1) above, displacement ε generated on the tracing axis
The correction speed vector V is determined by the gain G set as x.
The X-axis components of C ₁ , VC ₂ , and VC ₃ can be calculated, and similarly, the Z-axis component can be calculated by the displacement εz.

A command speed vector V for determining a cutter path corrected from the coordinate point Pc of the cutter head.
B ₁ , VB ₂ and VB ₃ are determined as follows. VxBi = Vx (i) + VxC (i) -VxC (i-1) VzBi = Vz (i) + VzC (i) -VzC (i-1) where i is a value in the current calculation cycle, i-1 Indicates the values in the previous calculation cycle, and the speed components Vx (i) and Vz of the tracer head determined by the following calculation
For (i), a value delayed by the delay in the FIFO memory 1, which is delay storage means, is actually used. That is, the difference VxC (i) -VxC of the correction command value obtained by multiplying the displacement amount of each axis received by the tracer head by a predetermined correction gain G.
(I-1), VzC (i) -VzC (i-1), and the corrected speed obtained by adding the speed command values Vx (i-1), Vz (i-1) to the respective axis drive commands VxB (i ), Vz
B (i) is stored in the FIFO memory 1.

If the FIFO memory 1 outputs each axis drive command VxB (i), VzB (i) to the main motor 36 with a delay of, for example, 10 operation cycles, the cutter reaches the coordinate point Pc with that delay. . Therefore, even if the amount of bite velocity vector of the tracer head toward V ₂ from V ₁ in the form suddenly changing portions of the model is increased,
The cutter head then applies the corrected axis drive commands VxB
(I), the cutter path determined according to VzB (i) is followed.

FIG. 3 is a block diagram showing the overall configuration of the copying control apparatus and copying machine according to the present invention. In the figure, a copying control device 20 has a CPU 11 for executing copying operations and various kinds of operations described above, a ROM 12 for storing a control program, a RAM 13 corresponding to storage means such as the register circuits 7 and 8, and a nonvolatile memory 14. are doing. The non-volatile memory 14 is backed up by a battery (not shown), and stores various parameters relating to the direction, speed, and the like input from the operation panel 21.

The servo amplifiers 22 and 23 receive a feed axis drive command from the copying control device 20 and drive the main motors such as the X axis and the Z axis. Also, servo amplifier 2
The sub-motors 4 and 25 receive auxiliary shaft drive commands from the copying control device 20 and drive sub-motors such as the X-axis and the Z-axis.
In order to enable three-dimensional copying, the copying machine tool 30 is provided with an auxiliary axis for each of three axes including a Y axis (not shown), which is superimposed in parallel with the feed axis. Then, the tracer head 31 on the side of the copying machine tool 30 detects displacement amounts εx, εy, and εz in the X-axis, Y-axis, and Z-axis directions generated when the stylus 32 at the tip thereof comes into contact with the model 33, and It is input to the control device 20.

The cutter 34 is attached to a column 35,
The column 35 is moved in the Z-axis direction by a main motor 36zm. The column 35 has a sub motor 37zs
And 37xs are mounted.
By 7zs and 37xs, the tracer head 31 further moves in the Z-axis direction and the X-axis direction while being superimposed on the movement of the column 35. The work 38 is fixed on a table 39 together with the model 33, and the table 39 is moved in the X-axis direction by a main motor 36xm.

The main motors 36xm and 36z
m rotates according to the feed axis drive commands Vxm and Vzm,
The submotors 37xs and 37zs rotate according to the speed command values Vxs and Vzs calculated from the following speed command values, and drive the tracer head ahead of the cutter head.

In the tracing machine tool 30 having the above-described configuration, the cutter 34 passes with a predetermined time delay while correcting the path of the tracer head 31 by the tracing control device 10. That is, the tracer head 31 follows the model 33 prior to the cutter 34, and the path of cutting by the cutter 34 is corrected according to the biting state of the tracer head 31. Therefore, when the bite occurs, the path is corrected so as not to cut into the workpiece 38 by cutting without forcibly stopping the movement of the cutter, and the continuous copying can be performed.

In the above description, the correction arithmetic circuit 5 determines the correction command value for the feed axis drive command by multiplying the displacement amount received by the tracer head by a predetermined correction gain.
The correction command value may be determined according to the difference between the components εx, εy, εz of the displacement vector for each axis of the tracer head and the reference displacement at each predetermined calculation cycle.

[0030]

As described above, according to the present invention, an auxiliary shaft is provided to drive the tracer head independently of the tool shaft, and the movement of the tool is delayed in control, so that the tracer head apparently precedes the tool. The tool is moved with the speed command value according to the speed, so that biting of the tool can be reliably avoided. In addition, the tool can be controlled by a corrected path command different from the path of the tracer head relative to the model, and continuous contouring of the workpiece can be executed while preventing biting. Therefore, accurate tracing control in which the cutter does not bite into the work in the corner portion is realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing main control elements of a copying control device according to the present invention.

FIG. 2 is an XZ plan view showing an example of a relationship between a cutter path, a path of a tracer head, and a correction speed.

FIG. 3 is a block diagram showing an overall configuration of a copying control device and a copying machine tool according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 FIFO memory 2 Synthesizing circuit 3 Subtraction circuit 4 Compensation arithmetic circuit 5 Correction arithmetic circuit

──────────────────────────────────────────────────の Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B23Q 33/00-35/48 B24B 1/00-1/04 B24B 9/00-19/28

Claims (2)

(57) [Claims] 1. A calculates copying the displacement amount detected by the tracer head seek tracing speed command values of the respective feed axes, in Great had control device forms a Rioku Ri axis drive command by these if have the speed command value, An auxiliary axis control means for controlling an auxiliary axis provided to be superimposed on the feed axis and moving the tracer head relative to a model in parallel with the feed axis; and receiving the tracer head for each feed axis. accessory based correction calculating means for determining a correction command value for said feed shaft drive command is multiplied by a predetermined correction gain to the variable position, the tracing speed command value to said corrected command value
Means for correcting , and delaying the corrected speed command value by a predetermined time.
A delay means for outputting as a feed axis drive command; and a value of the feed axis drive command delayed and output by the delay means being subtracted from the following speed command value to output a speed command value to the auxiliary axis control means. And a subtraction means for performing the following. 2. The correction calculation means determines a correction command value in accordance with a difference between a component εx, εy, εz of a displacement vector for each axis of the tracer head and a reference displacement at each predetermined calculation cycle. 2. The copying control device according to claim 1, wherein: