JPH0463678A - Automatic size measuring device for grindstone - Google Patents

Abstract

PURPOSE:To correctly measure the size of a grindstone by providing a contact- less distance sensor arranged to face the outer periphery of the grindstone, an A/D converter converting the analog output of the distance sensor to the digital quantity, and a grindstone outer diameter calculation section calculating the outer diameter of the grindstone with the digital output. CONSTITUTION:A contact-less distance sensor 2 arranged to face the outer periphery of a grindstone 1 is normally of an electrical type, and it generates an analog signal corresponding to the change quantity of the outer diameter of the grindstone 1 due to depletion or dressing. The analog output of the sensor 2 is converted into the digital quantity usable for the calculation in a numerically controlled (NC) device by an A/D converter 4 and outputted to change part of the NC program in response to the diameter of the grindstone 1 by utilizing this analog signal. The outer diameter of the grindstone 1 is calculated by a grindstone outer diameter calculation section 7 by utilizing the digital output, and part of the NC program is changed based on the outer diameter of the grindstone 1 to finish a work to the desired size.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic dimension measuring device for automatically measuring the outer diameter of a grinding wheel in a numerically controlled grinding machine.

Conventional technology The outer diameter of the grinding wheel changes due to abrasive wear and dressing during grinding, which affects the finished dimensions of the workpiece, so knowing the outer diameter of the grinding wheel is necessary for automatically controlled machining using numerical control etc. be. However, since the abrasive grains protrude from the surface of the whetstone, it is impossible to measure dimensions by directly applying the measuring point of a dimension measuring device to the surface of the whetstone while the whetstone is rotating because the measuring point will be scraped by the abrasive grains. Therefore, conventional grindstone size control is based on the position of the dressing tool, which is in a certain relationship with the workpiece, as shown in Figure 2, or based on the dressing cutting depth, as shown in the block diagram in Figure 3. The tool dimensions of the grindstone were corrected sequentially by subtraction from the initial grindstone dimensions. There is also a method that uses an air micrometer to measure the position of the grinding wheel surface without contact.

Problems to be Solved by the Invention In the method shown in Figure 2, which measures the position of the grinding wheel surface, the dressing tool position is in a constant relationship with the workpiece, so during grinding, the position of the dressing tool is measured from the grinding wheel position at the end of dressing to that constant relationship position. By sending the grindstone to a point corresponding to , the desired workpiece size can be obtained. In the method shown in FIG. 3, the dressing depth of cut is always subtracted from the initial grindstone diameter, so the current value of the grindstone diameter is always incorporated into the numerical control program, so that so-called tool correction can be performed. However, these methods do not take into account the wear and tear of the dressing tool, so there is a problem in that highly accurate tool dimension management is not possible. Further, in the electrolytic dressing method, since the electrode is located far from the grindstone, there is a problem in that it is impossible to control the size of the grindstone based on the position of the electrode. Furthermore, the method using an air micrometer has the problem that it is not always possible to accurately measure the dimensions of the grinding wheel due to the influence of air flow on the surface of the grinding wheel and the influence of the grinding fluid.

The present invention was developed in view of the above-mentioned problems of the conventional technology, and its purpose is to measure the outer diameter of a grindstone without contact and to automatically and accurately control the size of the grindstone. The aim is to provide an automatic measuring device.

Means for Solving the Problems In order to achieve the above objects, the present invention provides a non-contact distance sensor that is arranged to face the outer peripheral surface of a grinding wheel, and an A/D that converts the analogue output of the distance sensor into a digital quantity. The conversion device and the numerical control device j14 include a grindstone outer diameter calculation section that calculates the grindstone outer diameter using the digital output. The numerical control device also includes a grindstone rotation speed data memory.

A non-contact distance sensor placed opposite the outer circumferential surface of the working wheel is typically electrical and generates an analog signal corresponding to the amount of change in the outer diameter of the wheel due to wear or dressing. In order to change part of the numerical control program according to the grinding wheel diameter using this analog signal, the analog output of the sensor is converted into a digital quantity that can be used for calculations within the numerical control device using an A/D converter. Output. Using the digital output, the outer diameter of the grinding wheel is calculated by the outer diameter calculation section of the grinding wheel, and a part of the numerical control program is changed based on the outer diameter of the grinding wheel to finish the workpiece to the desired dimensions.

Also, find the runout per rotation of the grindstone.

Embodiment The apparatus of the present invention extracts only the relevant parts from the numerical control apparatus, and as shown in FIG. A non-contact electrical dimension measuring device consisting of a door 2 and an amplifier 3 is connected to the arranged sensor, and this non-contact electrical dimension measuring device has a measurement interval of the bottom part with respect to magnetic metal and has a resolution of less than μm. Sensor head for example cubic il! (KK)
It is possible to use the sensor head of the E2CA type linear proximity sensor manufactured by Company A. An A/D converter 4, a program memory 5 that stores part programs that determine the operating order of the numerically controlled machine tool, a program analysis section 6 that reads and analyzes the part programs stored in the program memory 5 one by one, and a grindstone diameter. A grindstone outer diameter calculation unit 7 that performs measurement control, calculation, and storage, a coefficient data memory 8 that stores the actual distance Km per unit of digital quantity output from the A/D converter 4, and a grindstone rotation specified in the part program. It includes a numerical control device having a grindstone rotation speed data memory 9 for storing the number N/win.

Next, the present invention will be explained in detail with reference to FIG.

In a numerically controlled grinding machine, when the outer diameter of the grinding wheel changes due to wear or dressing, the movement of the grinding wheel head is regulated by the numerical control program, so although the workpiece remains the same, the diameter of the workpiece changes by the amount of change in the diameter of the grinding wheel. It cannot be finished to the dimensions of . In order to finish the workpiece to the desired dimensions, it is necessary to change part of the numerical control program depending on the diameter of the grinding wheel.

After initial dressing, trial grinding is performed to accurately measure the diameter XW of the workpiece, and the grinding wheel axis position Xg given by the numerical control program or manually input is reversely calculated from the measured diameter XW of the workpiece. To accurately estimate the grindstone diameter Xs (normally Xs = 2 D converter 4
The output value, the value stored in the coefficient data memory 8, and the product value of Tsuru are also calculated by the grindstone outer diameter calculation unit 7 and stored there. After the 0-order dressing, the current value is determined by the command from the grindstone outer diameter calculation unit 7. The stored L is subtracted from the product of the output value of the A/D converter 4 indicating the distance between the sensor head 2 and the grinding wheel 1 and the stored value KwM of the calculation data memory 8 to obtain ΔL.
, find.

Also, instead of the memorized value, Ll is used in the grindstone outer diameter calculation section 7.
to be memorized. Since ΔL1 is the radius value of grinding wheel wear due to dressing, the grinding wheel diameter dimension X31 after dressing is
It can be easily obtained as s + = X s 2 ·ΔL+. This value of XS is also stored in the grindstone outer diameter calculation section 7. It is easily understood that when grinding is performed after dressing, the correct workpiece diameter XW can be obtained by performing so-called tool correction and using XS as the value of the grindstone diameter in the numerical control program.

In this way, the amount of change in the grindstone surface position is subtracted from the grindstone diameter each time dressing is performed, and the correct grindstone diameter can always be obtained, and the tool dimension correction in the numerical program can be performed correctly.

Further, using the combination according to the present invention, the time for one rotation of the grindstone is determined from the grindstone rotation speed stored in the grindstone rotation speed data memory 9, and the sensor head 2 and the grindstone 1 are
The values of the intervals are sampled and recorded in the grindstone outer diameter calculation unit 7, and the runout of the grindstone can be determined from the maximum value L wax and the minimum value Lmin.

This value is used for determining the completion of dressing and for quality control. During these measurements, the position of the bond surface is measured, not the position of the abrasive grain tip that protrudes from the bond surface, but if the dressing conditions are the same with the same grinding wheel, the amount of abrasive grain protrusion is considered to be constant. Therefore, the amount of change in the outer diameter of the grinding wheel can be accurately determined using the above-mentioned detection method.

Effects of the Invention Since the present invention is configured as described above, it has the following effects.

The device according to claim 1 can accurately measure the dimensions of a rotating grindstone without being affected by grinding fluid, air flow, or dressing tool wear, and can improve the accuracy of machining by numerical control. Contributes to improvements and increased efficiency.

The apparatus according to the second aspect of the present invention is capable of detecting the runout of the outer circumferential surface relative to the rotating grindstone, so that it is possible to determine when to finish dressing, and it is possible to automate dressing and improve product quality.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an automatic metal bond grindstone dimension measuring device according to the present invention, Fig. 2 is a schematic explanatory diagram of a conventional grindstone diameter correction method that uses the grindstone position at the end of dressing as a reference, and Fig. 3 The figure is a schematic block diagram showing a conventional grindstone diameter correction method in which the dressing depth of cut is always subtracted from the initial grindstone diameter. 1... Magnetic metal bond grinding wheel 2... Sensor head 3... Amplifier 4... A/D converter 5... Program memory 6... Program analysis section 7... Grinding wheel diameter calculation section 8... Coefficient data memory 9.・Whetstone rotation speed data memory

Claims (2)

[Claims] (1) In a numerically controlled grinding machine, there is a non-contact distance sensor placed on the outer peripheral surface of the grinding wheel, an A/D converter that converts the analog output of the distance sensor into a digital quantity, and a numerical control device that uses the digital An automatic grindstone dimension measuring device including a grindstone outer diameter calculation section that calculates the outer diameter of the grindstone using the output. (2) The automatic grindstone dimension measuring device according to claim 1, wherein the numerical control device includes a grindstone rotation speed data memory.