JPS61109646A - Automatic machining point correcting device for machine tool - Google Patents

Abstract

PURPOSE:To improve the machining accuracy while to monitor abnormal correcting operation by providing means for correcting the co-ordinates of mechanical system through automatic measurement of work face while employing the tool as a touch sensor. CONSTITUTION:Work detecting means employing the tool as a touch sensor 3 is provided while in order to perform approach operation of work detecting means, approach point operating means 6x and position data feeding means 5x are provided. While in order to correct the machining operation on the basis of the measurement results, shifting amount detecting means 8x and co- ordinates operating means 9x are provided. Furthermore, in order to provide sequences of commands for interlocking said means, memories for various data or programs and CPU16 are provided. Consequently, the work detecting means is moved by the amount determined for every work until contacting against the work to calculate the distance to the work thus to correct the mechanical system co-ordinates of work.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to machining centers and numerical control systems that are equipped with a plurality of tools and automatically machine a workpiece by specifying the coordinate position of the tools while selecting and exchanging the tools. The present invention relates to an automatic machining point correction device that automatically corrects workpiece installation errors and tool flow rates in a machining point setting device such as a machine tool.

[Conventional technology]

In machining centers and numerically controlled machine tools,
The workpiece attached to the table is machined based on numerical control data such as mechanical system coordinates inputted in advance using tape, etc., but the workpiece cannot be mounted unless the position is accurately matched to the mechanical system coordinate data. There is a problem that errors occur. For this reason, in the past, fixture mechanisms were devised for each type of workpiece to improve mounting accuracy, but these lacked versatility and were expensive, and due to aging, etc., it was difficult to achieve a completely accurate match. . There is also a method of correcting the machine system coordinate data by measuring the mounting error with a micrometer, etc., but it is extremely inconvenient to correct it every time a workpiece is mounted (it is also complicated to operate and reduces the operating rate of the machine tool). , it was not suitable for automated equipment.In addition, in the past, before machining a workpiece, it was not checked whether the workpiece was installed correctly and whether the mechanical system was operating normally.For example, FMS (flexible・In automated equipment such as manufacturing systems, where workpieces are automatically mounted using robots, malfunctions can cause incorrect machining or breakdowns, which can lead to various major troubles. Something happened.

Furthermore, the movement mechanism of each machining axis has a so-called flow rate, which may exceed the stop position due to inertia or may cause delays in the electrical system, although it may be small. In the past, this was treated as a permissible error range for processing accuracy and was overlooked, but in today's world where quality improvement is required, it has become a problem that cannot be overlooked.

[Problem that the invention seeks to solve]

The present invention was made in view of the above-mentioned shortcomings in conventional numerically controlled machine tools, machining centers, etc., and aims to correct the machining operation for each workpiece even if there is an error in the installation of the workpiece. Automatically detecting the operating direction of the tool and correcting the so-called flow rate to achieve extremely high machining accuracy, and increasing safety by monitoring abnormalities in the operation during correction operations. The goal is to have flexibility and versatility for the workpieces, and to make the operation extremely simple.In addition, it is ideal for automation and labor saving such as FMS, and is also suitable for correcting workpiece installation. The aim is to improve efficiency by shortening the time spent.

[Means for solving problems]

In order to achieve the above object, the present invention is provided with a workpiece detection means such as a tool as a touch sensor, an approach point calculation means and a position data transmission means for causing the workpiece detection means to perform an approach operation, and a measurement result It is equipped with a shift amount detection means and a coordinate system calculation means in order to correct the machining operation, and a central processing unit (hereinafter referred to as CPU) is equipped with a memory for various data and programs and a central processing unit (hereinafter referred to as CPU) to provide procedures and commands to collectively link these means. It is characterized by having a

[For production]

In the present invention, a workpiece detection means such as a touch sensor is moved by a predetermined movement amount for each workpiece, that is, an approach amount, until it comes into contact with the workpiece, and when it comes into contact, it is stopped and the distance to the workpiece is calculated. This is to correct the machining operation by correcting the mechanical system coordinate values of the workpiece in the machining data. At this time, by setting multiple approach points, it is possible to judge the rationality of the operation, that is, abnormality, depending on whether or not a workpiece is detected during each movement.When correcting the zero mechanical system coordinate values, The means of the present invention which improves machining accuracy by taking into account the so-called tool flow rate automatically and speedily perform the above operations.

〔Example〕 Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of automatic machining point correction values for a machine tool of the present invention, and FIG. 2 is a schematic side view of a typical machine tool. First, the configuration will be explained. Figure 1 and below
Although only the axis is described, as shown in Figure 2, the Y axis,
In a multi-axis machine tool that also has a Y-axis, similar means can be provided for each axis. In this case, a symbol with an X added in the diagram indicates that it exists in each axis muscle, and it can be explained by replacing X in Figure 1 with Y or Z, so parts other than the X axis Since the explanation will be complicated, it will be omitted. In Fig. 1, the automatic machining point correction device is a tape reader 1 that reads numerical control data for machining.
．． Keyboard with CRT screen for inputting approach amount, etc. 2. A touch sensor 3 for detecting a workpiece and a touch detection circuit 4 for emitting a touch signal. A touch sensor 3 is connected to a position data sending means 5 consisting of a servo motor, an encoder, an interpolator, etc. that moves each axis for processing the workpiece.
approach point calculation means 6x for calculating the approach point of
Motion direction determining means 7x for determining the direction of approach motion
, a shift amount detection means aX that calculates the shift amount S ftX of the mechanical system coordinate value from - in the flow rate, and a coordinate system calculation means 9 that corrects the original mechanical system coordinate value of the workpiece from the shift amount S□8.
10. A motion monitoring means for comparing the approach position and the work surface position during the approach motion, determining the rationality of the motion, and monitoring abnormalities. , Cannibal program memory 11° Tool damage detection program memory 12. Touch program memory 13
．． Initial setting value memory 14. Conversion data memory 15. It is composed of a CPU 16 etc. that controls each means.

FIG. 2 shows an example of a typical machine tool to which the present invention is applied, in which a workpiece W is attached to a table T positioned in the X and Y directions, and a processing head C positioned in the Z direction.
It is composed of a touch sensor 3, which is a rotating tool during machining, and also serves as a workpiece detection means during approach operation.

The touch sensor is arranged on the fixed side of the processing head C, and forms a closed/open circuit the moment the touch sensor (tool) 3 makes conductive contact with the workpiece W, and detects the current flowing in the closed circuit by electromagnetic induction, etc. .

Figures 3 (A) and (TI) show the workpiece W in the present invention.
3 is a diagram showing the relationship between the tool and the touch sensor 3. FIG. The present invention provides versatility to the cannibal program so that it can be machined either in FIG. 3 (A) or ([I) depending on the location of the tool 3. In this case, processing is performed using the sign of the coordinate system from the processing origin of the Kani program. In other words, in the coordinate system of Fig. 3 (a), it is a positive sign, and Fig. 3 (
El) has a negative sign. These codes are determined by the location of the touch sensor (tool) 3 in the Canadian program. Om is the coordinate origin of the mechanical system,
Xt+ is the original mechanical system coordinate value @5ftx is the shift amount, that is, the correction amount, and the corrected mechanical system coordinate value of the work surface W1 is Xt. By this correction, the machining origin OXI on the program, which has an error with respect to the mechanical system coordinates, can be brought into alignment with the machining origin Ox, which should originally be located, without correcting the position, tool 3, etc. of the workpiece W. Xo is a predetermined work surface program coordinate value, Xl is the actual work surface position, X2 is the first approach point of the touch sensor + Xs is the work surface W where a touch signal is detected, and touch signal detection that is measured by Point Xa is the second approach point. Further, α8 is the approach amount for calculating the first approach point, which indicates the safety confirmation range up to the point before the touch sensor 3 reaches the work surface W1, and β
One is the approach amount for calculating the second approach point, which indicates the range in which the touch sensor 3 searches the work surface W. When Signx is a code representing the operating direction of the touch sensor 3, the relationship between each numerical value is expressed by the following equation. That is, Xz=±lXo +α, l X4=Xo +Signx 8

5ttx -Xo X3 +Signx rgXr
MMXt+ + S ttx . τ8 is the flow rate of the tool 3. Note that the shaded W
b indicates the processing area.

Next, the operation of the automatic machining point correction device for a machine tool constructed as described above will be explained. FIG. 4 is a flowchart showing an example of the operation. Since the operation is almost the same for the X-axis, Y-axis, and Z-axis, only the X-axis will be explained here. In Fig. 4, the 0th stage calls the tool breakage detection program from the tool breakage detection program memory 12 in order to detect the breakage of the tool 3, and transfers the tool to the tool measurement standard jig (not shown in Figs. 1 and 2). 3. Perform positioning operation. In the 0th stage, the tool 3 is measured from a predetermined direction using a tool measurement reference jig to perform a damage detection operation. If damage is detected, an alarm is output and the operation of the machine tool is interrupted or stopped. The 0th stage is processing of the first approach point, in which the touch sensor 3, which also serves as a tool, is moved to a safety confirmation point where the touch setter 3 does not come into contact with the workpiece W, that is, the first approach point X2. This first approach point
! is calculated by the approach calculation means 6x using the calculation formula of X,=±lxa+α81 as described above. During this approach operation, the touch sensor 3 and the touch detection circuit 4
When the touch signal is detected, the operation monitoring means 10x issues an alarm, assuming that the mounting position of the workpiece W has deviated from the automatic correction capability range or that there is some abnormality in the operation of the machine tool or the automatic processing point correction device. to interrupt or stop a predetermined operation. That is, the first approach point X! 5. Position data sending means while moving to 5. The current value data X of
A range comparison of X≧X2 is performed in the comparator, and if a touch signal is detected during this period, an alarm is issued because it is a different workpiece that is larger than the expected workpiece. If it is normal at the 0th stage, the touch program is called from the touch program memory 13 for each operation of the x, y, and z axes at the 0th stage, and a correction operation is started. In the 0th stage, first, the original mechanical system coordinates of the workpiece, XA, etc., are transferred from the machine program memory 11 to the touch program memory 13 and conversion data memory 15, along with the tool axis rotation speed and feed rate, for correction. Ru. In the 0th stage, the approach calculation means 6X calculates the second approach point X4 from the approach amount β8, controls the touch sensor 3 so that it can move to the approach point X4, and when a touch signal is detected during this approach operation, the approach operation is performed immediately. to stop. Before the approach point calculation means 6X for calculating the second approach point X4 and the cyst amount detection means 8x (to be described later) operate, the operation direction determining means 7X determines the direction of movement of the tool with respect to the workpiece.
The code Signx data determined by is input. That is, the comparator compares the first approach point Xz and the work surface program coordinate value X0 with respect to a preset operator command memory.

Xi Xo≧O-(A) It operates in one direction relative to the machining origin. Also, depending on this direction (sign), approach point calculation means 6x and shift)! Code processing is performed in the detection means 8x.

The above equation (B) means that the approach position of the tool 3 with respect to the mounting position of the workpiece is in the state shown in FIG.

Therefore, the ten sign processing is also performed in the approach calculating means 6x and the shift amount detecting means 8.

If the touch signal is still not detected even after reaching the second approach point X4, it is assumed that some abnormality has occurred, and an alarm is issued to interrupt or stop the predetermined operation. That is, while moving to the second approach point X4, the position sending means 5. The current value data X of I is compared in the range of x>x4 using a comparator, and if the data comparison ends without detecting a touch signal during this time, an alarm will be issued as it is a different workpiece that is smaller than the expected workpiece. be. In the 0th stage, if a touch signal is detected during the approach operation to the second approach point X2, the shift amount detection means 8. The current position of the measuring means 58 is read out at , and this is set as the touch signal detection point X3.
o −X 2 +Signx τ, shift amount 5tt
Calculate x. In the 0th stage, the coordinate system calculation means 9x shifts the work surface Wa to the original mechanical system coordinate value XTI by an amount of 5f.
tx is added to calculate the corrected mechanical system coordinate value Xy.

This XT is transferred to the cannibal program memory 11, and the machining operation is performed by calling the cannibal program in the cannibal program memory 11 in the 0th stage, but since the mechanical system coordinate values have been corrected, the mounting of the workpiece is not possible due to errors. High-precision machining that takes into account flow rate can be achieved. When the machining is completed, the corrected mechanical system coordinate values in the machine program memory 11 and the conversion data memory 15 are transferred to the original mechanical system coordinate values stored in the conversion data memory 15, and then restored. At stage 0, the recovery process for the Canadian program and the touch program is performed. With the above steps, the series of operations is completed and preparations are made for the next machining operation.

The object of the present invention is not limited to the machining centers and numerically controlled machine tools mentioned at the beginning (it goes without saying that it can also be applied to general machine tools equipped with a single tool).

〔effect〕

As described above, in the present invention, even if there is an error in mounting a workpiece on a machine tool, it is a simple operation that gives the approach amount and tool flow rate at the initial stage, and from the subsequent machining, the tool becomes a touch sensor before the start of machining and the workpiece surface Since the machine automatically measures the coordinate values of the mechanical system and corrects the machining operation, it has been possible to significantly improve machining accuracy compared to conventional methods.

Further, since the above-mentioned operation is only inputted at the initial stage, and the correction operation is performed automatically and quickly, the effect of improving work efficiency and operating rate of the tool machine and increasing productivity has been obtained.

This compensation method also automatically determines the direction of tool movement relative to the workpiece, and since it is extremely cylindrical, it can flexibly handle a variety of workpieces and has versatility, allowing it to machine a wide variety of workpieces in random order. It has become possible to make it optimal for automating processing in machining centers and the like.

In addition, in the correction operation, it is possible to monitor abnormalities in the operation of the touch sensor and stop the operation if there is a dangerous situation, which has the effect of greatly increasing safety. This will also have the effect of supplying machine tools that are compatible with automation and labor saving.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of the present invention, Fig. 2 is a side view of a machine tool showing an example to which the invention is implemented, and Fig. 3 (A).
and (υ) are explanatory diagrams showing the relationship between the workpiece and the tool (touch sensor) in the present invention, and FIG. 4 is a flowchart showing the operation of the embodiment of the present invention. ■...Tape reader 2...Keyboard 3...
・Touch sensor (tool) 5X...position data sending means 6,...approach point calculation means 7X...movement direction determining means 8X...shift amount detection means

Claims (5)

[Claims] (1) A workpiece detection means for grasping the workpiece surface position as a means of machining with a machine tool, a means for inputting the approach amount of the workpiece detection means, a memory for storing the approach amount, etc., and a memory that stores the approach amount etc. approach point calculation means for calculating the approach point of the approach point, position data sending means for detecting the work surface and measuring the work surface position while the work detection means is moving to the approach point, and calculating the work surface position and processing numerical control data. A shift amount detection means that calculates an error value from the coordinate value, that is, a shift amount of the coordinate system, and a coordinate system calculation means that calculates a corrected coordinate value of the workpiece based on the shift amount, and each of the above-mentioned means are integratedly linked. An automatic processing point correction device for a machine tool, characterized by comprising a central processing unit. (2) The automatic machining point correction device for a machine tool according to claim 1, wherein the workpiece detection means is comprised of a touch sensor and also serves as a tool. (3) The automatic machining point correction device for a machine tool according to claim 1 or 2, wherein the shift amount detection means also adds the flow amount of the tool. (4) The approach point calculation means comprises a movement direction determining means that automatically determines the movement direction from the positional relationship between the machining origin of the workpiece and the tool. An automatic machining point correction device for a machine tool according to any one of paragraphs. (5) Any one of claims 1 to 4, wherein the position data sending means comprises operation monitoring means for monitoring abnormalities in the moving operation of the workpiece detection means to the approach point. Automatic machining point correction device for machine tools described in .