JPH01281852A - Measuring device for machine tool and working dimensions - Google Patents

Abstract

PURPOSE:To enable a high-precision working, in which error factors have been corrected, to be achieved by calculating the working error after working on the basis of the position information obtained by a measuring means, and by using a tool correction value, in which modification has been made to correct the calculated working error, for carrying out working. CONSTITUTION:Once the working of a workpiece 15 is finished, leaving the workpiece 15 and a tool 17 as they are, the positions of both the work surface 15A of the workpiece 15 and a work reference surface 14A are measured by the contact detection of a work dimension measuring device 3. And, the tool correction value is corrected on the basis of the work dimension error calculated from the measured positions, and using this corrected tool correction value, reworking of the workpiece 15 is carried out. Thus, the working of the workpiece is carried cut by using the tool correction value in which not only the dimensional error of the tool 17 but also various error factors are corrected. By the above constitution, a high-precision working, in which various error factors such as thermal deformation, wear of the tool have been corrected, can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a machine tool having a function of correcting the machining dimensions of a workpiece and a measuring device therefor.

``Prior Art'' In a machine tool equipped with a numerical control system R (NC device), machining dimensions are corrected by setting a tool correction amount.

If the tool compensation amount is set only based on the tool dimensions measured with a tool presetter, etc., it will not be possible to compensate for the effects of machine tool and tool deformation, thermal displacement, tool wear, etc. It is necessary to measure the dimensions of the workpiece and correct the tool compensation amount.

Conventionally, the dimensions of a workpiece have been measured by removing the workpiece from the machine tool and measuring it outside the machine.

In addition, automatic tool changers (ATC) for machining centers, etc.
For those equipped with a measuring device), the measuring device is installed in the tool holder as one of the tools in the ATC device, and when the tool is replaced, the measuring device is attached to the spindle to measure the dimensions of the workpiece. There was something I did.

``Problem to be solved by the invention'' However, measuring the machining dimensions of a workpiece outside the machine requires a lot of work time, and it takes a lot of work for the operator to properly correct the amount of tool compensation from the measurement results. There was a problem in that a hot wire was required.

In addition, when using an ATC device, the tool must be replaced once for measurement, which results in wasted time, and the attachment state of the machining tool to the spindle changes slightly before and after measurement. There was a problem in that the results could not be accurately reflected in the correction values.

The present invention has been made to solve the above problems, and its purpose is to measure the dimensions of a workpiece without changing the attachment state of the tool and workpiece during machining, and to An object of the present invention is to provide a machine tool that can automatically correct machining dimensions and perform machining, and a measuring device therefor.

"Means for Solving the Problem" In order to achieve the above object, the present invention, as shown in FIG. 1, includes a numerical control device 1 having a tool correction function and a A machining dimension measuring device 3 having a contact detector 4 is installed near the headstock, and after machining the workpiece, the workpiece and the machining dimension measuring device 3 are moved relatively, and the contact detector 4 detects the workpiece. a first measuring means 5 for storing the position of contact with the machining surface; and a second measuring means 5 for storing the position of contact of the contact detector 4 with the machining reference surface by moving the workpiece and the machining dimension measuring device 3 relative to each other. a measuring means 6, a machining error calculating means 7 for calculating a machining error of the workpiece after machining based on the position information obtained by the first and second measuring means, and correcting the calculated machining error. a tool correction value correcting means 8 for correcting the tool correction value to the desired value; and a processing means 9 for processing the workpiece using the corrected tool correction value.
A machine tool is provided that is characterized by comprising:

Further, as a measuring device for the machine tool, as shown in FIG. 2 which is an embodiment drawing, a bell crank 23 swingably supported on the side of the headstock 12, and one of the bell cranks 23 are used. A contact detector 4 is provided between the other arm 23B of the bell crank 23 and the headstock 12, and the contact detector 4 is fixed to the end of the arm 23A of the workpiece 15.
an actuator 26 that swings the bell crank 23 between a measurement position where it can come into contact with the workpiece 15 and a storage position where it escapes from the workpiece 15; There is provided a machining dimension error device M3 characterized in that it includes a stopper 31 that restricts the swinging position of the bell crank 23 against the biasing force of the actuator 26.

"Operation" In a machine tool configured as described above, when the machining of the workpiece is completed, the machining surface of the workpiece and the machining standard are determined by the contact detection of the machining dimension measuring device, while the workpiece and tool remain as they are. The position of the surface is measured. Then, the tool correction value is corrected based on the machining dimensional error calculated from that position, and the workpiece is reworked using the corrected tool correction value. Therefore, the workpiece is machined using tool correction values that include not only the dimensions of the tool but also various error factors.

Also, is there a machining dimension measuring device configured as above? J! 3
Now, by driving the actuator 26 in one direction, the contact detector 4 is projected to the measurement position, and by driving the actuator 26 in the other direction, it is housed in the storage position.

In the measurement position, the bellcrank 23 is connected to the actuator 26
The stopper 31 is pressed against the headstock 12 and fixed. Therefore, even if there is play in the bearing portion 22 that supports the bell crank 23, the position of the contact detector 4 will not fluctuate during the measurement operation when it is fixed at the measurement position.

"Example" Embodiments of the present invention will be described with reference to the drawings.

2 and 3 are front views showing a grinding machine to which the present invention is applied.

A headstock 12 is provided on the fixed column 11 so as to be movable in the vertical direction. Moreover, the table 13 is movable in the left-right and front-back directions. Headstock 12 and table 1
3 is driven by a feed motor (not shown), and the NC device 1
Its position is controlled by A jig 14 is fixed on the table 13, and a workpiece 5/1A15 made of a ceramic material is placed and fixed on the jig 14. A grinding tool 17 is attached to a main spindle 16 rotatably provided on the headstock 12, and grinds a workpiece 15.

A machining dimension measuring device 3 is provided on the side surface of the headstock 12. That is, a box-shaped bracket 21 is fastened to the lower side of the headstock 12, and a bell crank 23 is swingably supported by a rolling bearing 22 provided on the bracket 21. One arm of Bellcrank 23 (long arm)
A contact detector 4 is fixed to the tip of 23A. For this contact detector 4, for example, a high-precision switch with particularly excellent repeatability is used. A bracket 25 is fastened above the same side of the headstock 12, and a pneumatic cylinder 26 is connected between the bracket 45 and the other arm (short arm) 23B of the bell crank 23. The rear end of the head portion of the pneumatic cylinder 26 is connected to the bracket 25 by a shaft 27.
On the other hand, a connecting member 29 is fixed to the tip of the piston rod 28, and is pivotally connected to the short arm 23B of the bell crank 23 by a shaft 30 provided on the connecting member 29. There is. The pneumatic cylinder 26 serves as an actuator for swinging the bell crank 23.

A stopper 31 is provided protruding near the base of the long arm 23A of the bell crank 23. As shown in FIG. 3, this collar 31 comes into contact with the side surface of the headstock 2 when the screw 1-rod 28 of the pneumatic cylinder 26 is extended.
The swinging position of the bell crank 23 is regulated. The swinging position where the pneumatic cylinder 26 is extended and the stopper 31 is brought into contact with the headstock 12 constitutes a measurement position where the contact detector 4 can come into contact with the workpiece 15. On the other hand, the pneumatic cylinder 26 is retracted and the long arm 23A of the bell crank 23 is oriented to the side of the headstock 12, which is not shown in FIG.

In the fixed position, the bell crank: 23 is the pneumatic cylinder 2
The stopper 31 is pushed against the headstock 1-2 by the urging force of 6.
It is fixed in the attached state. For this reason, assuming that the center axis of rotation of the rolling bearing 22 moves by a few μ, it is securely fixed when the end is pressed against the stopper 31.
In this way, the processing dimension measuring bag according to the present embodiment does not allow the position of the contact detector 4 to fluctuate. 1!3 has the advantage that the contact detector 4 can be moved and fixed at the measurement position at the same time using one pneumatic cylinder 26.

Here, the upper surface 15A of the workpiece 15 is ground to a height of 1 mm. For this purpose, processing, measurement, and correction processing are performed continuously.

These are realized as processing by a computer within the NC device 1. FIG. 4 is a flowchart showing the processing.

When the process 100 is started, first, the workpiece 15 is machined according to the given NC machining program (step 101). At this time, the pneumatic cylinder 26 is retracted and the contact detector 4 is placed in the retracted position. When the machining is completed, the headstock 12 is raised, and then the pneumatic cylinder 26 is extended to bring the bell crank 23 to the measurement position (step 102).

Then, the headstock 12 and table 13 are moved, and the headstock 12 is lowered until the contact detector 4 contacts the machining surface 15A of the workpiece 15 and a contact signal is input (step 10
3), and store the position H3 of the headstock 12 at the time when the contact was detected (step 104), step 10
3 and 104 constitute the first measuring means 5.

Next, the spindle white 12 is raised to separate the contact detector 4 from the workpiece 15, and the table 13 is moved to bring the contact detector 4 into contact with the machining reference surface 14A of the jig 14.
2 (step 105), and stores the position H1 of the headstock 12 at the moment the contact is detected (step 1
06), the processing of steps 105 and 106 constitutes the second measuring means 6.

Next, the headstock 12 is raised, and the pneumatic cylinder 2
6 is retracted to bring the bell crank 23 to the retracted position (step 107).

In step 108, the machining dimensions of the workpiece 15 are calculated based on the positional information H1, H1 stored in steps 104 and 106, and the machining error with respect to the 1-inch dimension is calculated. If the calculated machining error is within the predetermined tolerance, the process jumps from step 109 to step 112, and the current process 100 ends. If the machining error is greater than or equal to a predetermined tolerance, the process proceeds from step 109 to step 110.

In step 110, in order to correct the machining error, the tool correction value set and stored in the NC device 1 is corrected by the amount of the error. Then, the workpiece 15 is re-machined using the corrected tool correction value (step 111), and the series of machining processes 100 is completed.

As explained above, in this machine tool, after machining the workpiece 15, the machining dimensions are determined without removing the workpiece 15 and the tool 17 from the machine tool, and if there is a machining error, the tool is corrected. The values were corrected and reworked immediately. Therefore, the corrected tool correction value incorporates all various error factors depending on the state of the machine, such as thermal displacement and tool wear at that time, making it possible to perform highly accurate machining. In addition, since this series of processing is performed automatically,
The time required for this is small, and high processing efficiency can be ensured.

This embodiment uses a high-precision switch in the contact detector 4 to mechanically detect the position of the machined surface 15A of the workpiece 15, so it can be easily applied to the workpiece 15 made of non-ferrous materials such as ceramics. . It also has the advantage of being able to be provided at low cost.

In the above embodiment, the case where the height dimension of the workpiece 15 is corrected is explained as an example, but a plurality of contact detectors are installed at the tip of the long arm 23A of the bell crank 23 to detect contact from each direction. It is clear that it is also possible to provide, detect and correct the width dimension of the workpiece 15.

"Effects of the Invention" As explained above, since the present invention is configured as described above, it is possible to perform high-precision machining by correcting various error factors such as thermal displacement and tool wear. effective.

Furthermore, since the machining dimension measuring device of the present invention aims to move and fix the contact detector with a single actuator, it has a simple structure and can be provided at low cost, and is extremely easy to install on existing machine tools. It has the effect of being easy. Therefore, an existing machine tool can be modified into the machine tool of the present invention by simple modification.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, FIG. 1 is a diagram clearly showing the structure of the invention, FIGS. 2UgU and 3 are front views showing a grinding machine to which the present invention is applied, and FIG. 4 is an actual processing. It is a flowchart which shows. 119. numerical control device, 261. Machine tools, 31.
. Machining dimension measuring device, 4.1. Contact detector, 12. . , headstock, 14. ,Jig, 14A, Machining reference surface, 15-, Workpiece, 15A, Machining surface, 23, Bell crank, 26, Pneumatic cylinder (actuator), 31, Stopper . Figure 4

Claims (1)

[Claims] 1. A numerical control device having a tool correction function, a machining dimension measuring device installed near the headstock and having a contact detector that can come into contact with the machining surface of the workpiece, and a a first measuring means that relatively moves the workpiece and the machining dimension measuring device and memorizes the position where the contact detector contacts the machined surface of the workpiece; and a first measuring means that relatively moves the workpiece and the machining dimension measuring device. a second contact detector for storing a position at which the contact detector contacts the machining reference surface;
a measuring means, a machining error calculating means for calculating a machining error of the workpiece after machining based on the position information obtained by the first and second measuring means, and a machining error calculating means for correcting the calculated machining error. A machine tool comprising: a tool correction value correction means for correcting a tool correction value; and a processing means for processing a workpiece using the corrected tool correction value. 2. A bellcrank supported swingably on the side of the headstock, a contact detector fixed to the end of one arm of the bellcrank, and between the other arm of the bellcrank and the headstock. an actuator that swings the bell crank between a measurement position where the contact detector can contact the workpiece and a storage position where it escapes from the workpiece;
A machining dimension measuring device comprising: a stopper that comes into contact with the headstock at the measurement position and restricts the swinging position of the bell crank against the biasing force of the actuator.