JP7434054B2 - How to operate probing equipment in machine tools - Google Patents

Description

The present invention relates to a machine tool equipped with a coolant supply device and a probing device, and particularly to a method of operating a probing device in a machine tool equipped with a coolant supply device and a probing device.

Conventionally, a machine tool is equipped with a measuring device such as a probing device, and the measuring device is used to measure the dimensions, axis feed accuracy, etc. of a machined shape on the machine. For example, the analog measurement probe described in Patent Document 1 is used with a machine tool and includes a stylus for contacting the surface of a workpiece, and the stylus protrudes from the probe body and is movable to the probe body. connected to. The measurement probe further includes a sensor for measuring movement of the stylus relative to the probe body. The stylus of the analog measurement probe can be brought into contact with an object so that information about the shape or position of the object can be obtained. With analog probes, the magnitude (and optionally the direction) of stylus deflection is continuously sensed as the stylus is moved along the workpiece surface, and the deflection data is converted into data representative of the probe's position. In combination with this, detailed measurement results of the workpiece can be obtained.

In recent years, in response to the increasing speed and precision of grinding machines, there has been a need for probing and other measuring devices to be able to perform high-speed and high-precision measurements, and various proposals have been made for this purpose. There is. For example, in the conventional example described in Patent Document 2, the difference between the coordinates of a predetermined position of a machined workpiece and the reference coordinates, or the difference between the coordinates of a predetermined position of a machine tool and the reference coordinates, is detected by touching at a predetermined timing. The values measured by the probe are sequentially stored in the memory, and the history of the measured values stored in this memory is displayed together with the reference coordinates and tolerance values. From this history, the status of machining errors due to thermal deformation of the machine tool can be understood. do. Values handled in such systems are increasingly required to have higher resolution. However, in order to achieve high-resolution measurement, complex control is required for the operation of the measuring device, and precise and expensive measuring equipment must be manufactured separately, and the entire grinding machine must be This results in an increase in costs.

Special Publication No. 2014-517252 JP2007-007822A

As mentioned above, regarding the operating method of machine tools and their probing devices, we are developing probing devices that enable high-resolution measurements that are compatible with higher speed and higher precision machine tools without increasing the overall cost of the machine tool. Development is desired.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to enable high-resolution measurement that corresponds to higher speed and higher accuracy of machine tools without causing an increase in the overall cost of the machine tool. The purpose of the present invention is to provide a method for operating a probing device.

The inventor of the present invention attempted approaches from various viewpoints and conducted intensive research on how to operate a probing device that enables high-resolution measurements without increasing the overall cost of the machine tool mentioned above. We have obtained new and useful ideas regarding the configuration of the machine and the operating method of its probing equipment.

That is, in the method of operating a probing device in a machine tool according to the present invention, the machine tool is equipped with a probing device used for measuring a workpiece and a coolant supply device, and the probing device is waterproof and/or waterproof against coolant. For equipment that has oil performance and is equipped with a mechanism that digitally converts the signal level into a multi-level value rather than a binary value, a turbulent coolant flow is emitted toward the sensitivity direction of the probing device and output. To inexpensively reduce quantization noise of a desired signal frequency component by filtering a signal after being superimposed and digitally converted using a low-pass filter or a band-pass filter, and to simultaneously clean or cool the contact portion of a probe device with a workpiece. It is characterized by
Here, it is preferable to use a coolant nozzle with a flow path that induces turbulent flow, such as that provided by Rockline (registered trademark). Further, the amount of coolant should be large enough to avoid inducing turbulence and damaging the probe and workpiece.

Further, in a method of operating a probing device in a machine tool according to another aspect of the present invention, the machine tool is equipped with a probing device used for measuring a workpiece and a coolant supply device, and the probing device coolant is waterproofed and /Or for equipment that has oil-proof performance and is equipped with a mechanism that digitally converts the signal level into a multi-level value rather than a binary value, the coolant flow is intermittently radiated in the direction of sensitivity of the probing device to produce an output. The signal after being superimposed and digitally converted is filtered with a low-pass filter or band-pass filter to reduce the quantization noise of the desired signal frequency component at a low cost, and at the same time, the part of the probe device that comes into contact with the workpiece is cleaned. shall be.
Here, in order to allow the coolant to flow intermittently, a valve that can be turned ON/OFF continuously at high speed is prepared. Alternatively, use an intermittent output air device to turn the air operated valve ON/OFF at high speed. Alternatively, an intermittent output air device is used to direct this output to the coolant flow using a nozzle designed to rapidly change the direction of the coolant flow.

According to the present invention, it is possible to provide a method of operating a probing device that enables high-resolution measurements that correspond to higher speed and higher accuracy of machine tools without causing an increase in the overall cost of the machine tool. Furthermore, the contact portion of the probe device with the workpiece can be cleaned, and heat due to contact and friction can be effectively removed.

FIG. 1 is a diagram showing the basic configuration of a general probing device. 1 is a diagram showing the basic configuration of a first embodiment of the present invention, showing main parts of a machine tool equipped with a probing device and a coolant supply device; This is an example of using something that induces turbulence. FIG. 7 is a diagram illustrating the configuration of a second embodiment of the present invention, in which coolant is intermittently radiated from a coolant nozzle toward the sensitivity direction of a probing device by operating a valve. It is a figure which shows the structure of the 3rd Embodiment of this invention, and shows the form which blows air intermittently to the coolant injected from a coolant nozzle, and emits it toward the sensitivity direction of a probing apparatus. It is a diagram showing a control operation for measurement in the first embodiment of the present invention, in which the workpiece is measured (scanned) by moving the workpiece table with the stylus in contact with the workpiece while injecting coolant from the coolant nozzle. Indicates the form of 1 is a functional block diagram of a machine tool according to first to third embodiments of the present invention. FIG. 2 is a flowchart for explaining a measurement method using a probing device in a machine tool according to the first to third embodiments of the present invention, in which (a) is a flow of a conventional measurement method as a comparative example; ) respectively show the flow of the measurement method according to the embodiment of the present invention. FIG. 2 is a diagram for explaining a measurement method using a probing device in a machine tool according to an embodiment of the present invention; FIG. (b) is a functional block diagram common to cases in which the frequency of the signal changes depending on the feed rate, and is a diagram showing the gist of the control method in the case of (a) above. It is shown that the intermittent supply frequency and feed rate are controlled so that the sampling frequency /2, the cutoff frequency of the low-pass filter, and the signal frequency are in this vertical relationship. FIG. 3 is a waveform diagram for explaining the effects of the first embodiment of the present invention, in which (a) is an analog waveform without coolant, (b) is a digital waveform without coolant, and (c) is a waveform with coolant. (d) is a digital waveform with coolant, and (e) is a waveform passed through a digital low-pass filter with coolant.

First, in order to facilitate understanding of the present invention, a general probing device will be explained with reference to FIG. FIG. 1 is a diagram showing the basic configuration of a general probing device. The probing device is set and used in a main part of a machine tool such as a grinder (not shown) to perform on-machine measurement. As shown in FIG. 1, the probing device 10 is moved by a feeding device 12 so that a probe 14 and a stylus 16, which is a contact at its tip, can come into contact with or separate from a workpiece 18 placed on a worktable 17. By this, a signal is emitted when the tip (or tip ball) 16a of the stylus 16 comes into contact with the workpiece 18, so that the dimensions, axial feed accuracy, etc. of the processed workpiece 18 can be measured on-machine.

FIG. 2 is a diagram showing the basic configuration of the first embodiment of the present invention, showing the main parts of a machine tool equipped with a probing device and a coolant supply device, and the coolant nozzle is provided as a Rockline (registered trademark). This is an example of using a flow path that induces turbulent flow. That is, the probing device 20 in the machine tool of this embodiment is set and used in a main part of the machine tool (not shown) to perform on-machine measurement. As shown in FIG. 2, the probing device 20 is moved by a feeding device 22 so that a probe 24 and a stylus 26, which is a contact at the tip thereof, can come into contact with or separate from a work 28 placed on a work table 27. By doing so, by emitting a signal when the tip (or tip ball) 26a of the stylus 26 comes into contact with the workpiece 28, it is possible to measure the dimensions, axial feed accuracy, etc. of the shape of the processed workpiece 28 on-machine. .

Here, the machine tool of this embodiment is equipped with a probing device 20 used for measuring the work 28, and is also equipped with a coolant supply device 25, and the probing device 20 has waterproof and/or oil-proof performance against coolant and has a signal It is equipped with a mechanism to digitally convert the level into a multi-level value rather than a binary value. Then, the turbulent coolant flow is radiated in the direction of sensitivity of the probing device 20, superimposed on the output, and the digitally converted signal is filtered with a low-pass filter or band-pass filter. This makes it possible to reduce noise at low cost and to simultaneously clean or cool the portion of the probing device 20 that comes into contact with the workpiece 28. Here, it is preferable to use a coolant nozzle 25a of the coolant supply device 25 that has a flow path that induces turbulent flow, such as that provided by Lockline (registered trademark). Further, the amount of coolant should be large enough to induce turbulence, but should be large enough not to damage the probe 24 and workpiece 28.

FIG. 3 is a diagram showing the configuration of a second embodiment of the present invention, in which coolant is intermittently radiated from a coolant nozzle toward the sensitivity direction of a probing device by operating a valve. That is, the probing device 30 in the machine tool of this embodiment is set and used in a main part of the machine tool (not shown) to perform on-machine measurement. As shown in FIG. 3, the machine tool of this embodiment includes a probing device 30 used for measuring a workpiece 38 and a coolant supply device 35, and the probing device 30 has waterproof and/or oil-proof performance against coolant. It is equipped with a mechanism for digitally converting the signal level into a multi-level value rather than a binary value. Then, the coolant flow is intermittently radiated in the direction of sensitivity of the probing device 30, superimposed on the output, and the digitally converted signal is filtered with a low-pass filter or band-pass filter to eliminate the quantization noise of the desired signal frequency component. The cost can be reduced and the portion of the probing device 30 that comes in contact with the workpiece 38 can be cleaned at the same time. In the probing device 30, the probe 34 and the stylus 36, which is a contact at the tip thereof, are fed by the feeding device 32 so as to be able to come into contact with or separate from the work 38 placed on the work table 37, so that the stylus 36 Similar to the first embodiment, the dimensions, axial feed accuracy, etc. of the machined workpiece 38 are measured on-machine by emitting a signal when the tip (or tip ball) 36a of the machine contacts the workpiece 38. It is. Here, a valve that can be turned ON/OFF continuously at high speed may be provided to allow the coolant to flow intermittently. Alternatively, an air operated valve (not shown) may be turned ON/OFF at high speed using an intermittent output air device (not shown).

FIG. 4 is a diagram showing the configuration of a third embodiment of the present invention, and shows a form in which air is intermittently sprayed onto the coolant injected from a coolant nozzle and radiated toward the sensitivity direction of the probing device. That is, as shown in FIG. 4, in this embodiment, the intermittent output air device 49 is used to direct this output toward the coolant flow injected from the coolant nozzle 45a of the coolant supply device 45, so that the direction of the coolant flow changes at high speed. An intermittent air blow nozzle 49a designed as follows is used. Note that the probing device 40 in FIG. 4 is moved by a feeding device 42 so that a probe 44 and a stylus 46, which is a contact at the tip thereof, can come into contact with or separate from a workpiece 48 placed on a worktable 47. , the first and second machines measure the dimensions, axis feed accuracy, etc. of the processed workpiece 48 on-machine by emitting a signal when the tip (or tip ball) 46a of the stylus 46 comes into contact with the workpiece 48. This is similar to the second embodiment.

FIG. 5 is a diagram showing a control operation for measurement in the first embodiment of the present invention, in which the workpiece table is moved with the stylus in contact with the workpiece while injecting coolant from the coolant nozzle. Indicates the scanning form. That is, as shown in FIG. 5, in this embodiment, the probing device 50 causes the probe 54 and the stylus 56, which is the contact at the tip thereof, to approach the workpiece 58 placed on the worktable 57 using the feeding device 52. By moving the work table 57 as shown by the arrow 59, a signal is emitted when the tip (or tip ball) 56a contacts the work 58, thereby changing the dimensions and axis feed of the machined work 58. Accuracy etc. will be measured on the machine.

Next, with reference to FIG. 6, a machine tool to which the first to third embodiments of the present invention are applied will be described. FIG. 6 is a functional block diagram of the machine tool according to the first to third embodiments of the present invention. As shown in FIG. 6, the machine tool according to the first to third embodiments of the present invention has a control device 100, and this control device 100 includes a numerical control section 102, a sequence control section 104, and a digital control section 102. It includes a filter 106. The control device 100 is connected to a probing device (probe) 300, a coolant supply device or ON/OFF valve 400, and a shaft controller 500 via an input/output device 200, and the shaft controller 500 includes various motors 600. is connected. The input/output device 200 includes an analog input section 202, a digital output section 204, and an IO bus 206. The numerical control unit 102 issues a numerical control command to the axis controller 500 via the IO bus 206, and the axis controller 500 drives and controls the various motors 600 based on this numerical control command. A detection signal from a probing device (probe) 300 is processed (filtered) by a digital filter 106 via an analog input section 202, and the information is sent to a sequence control section 104 and further to a numerical control section 102. Based on this information, the sequence control unit 104 operates the coolant supply device or ON/OFF valve 400 via the digital output unit 204. Similarly, based on this information, the numerical control unit 102 issues a new numerical control command to the axis controller 500 via the IO bus 206, and based on this numerical control command, the axis controller 500 controls the various motors 600. to drive and control.

FIG. 7 is a flowchart for explaining a measurement method using a probing device in a machine tool according to the first to third embodiments of the present invention, and (a) shows a conventional measurement method as a comparative example. Flow and (b) respectively show the flow of the measurement method according to the embodiment of the present invention. As shown in FIG. 7A, in the conventional measurement method, when measurement starts (S701), measurement is performed using a normal probing device (S702), and the measurement ends (S703). In contrast, in the measurement method of the embodiment of the present invention, as shown in FIG. 7(b), when the measurement is started (S704), the intermittent coolant supply device is first turned on (S705), and then the above-mentioned Measurement is performed using the probing device prepared (S706). Subsequently, the intermittent coolant supply device is turned off (S707), and the measurement results are digitally filtered (S708), leading to the end of the measurement (S709). Note that the digital filtering described above may be performed as real-time processing during measurement.

FIG. 8 is a diagram for explaining a measurement method using a probing device in a machine tool according to an embodiment of the present invention, and (a) shows a method in which the ON/OFF frequency of a coolant supply valve can be switched. (b) is a functional block diagram common to cases where a low-pass filter is used and the frequency of the signal changes depending on the feed speed. It is shown that the intermittent supply frequency and the feed rate are controlled so that the supply frequency, the ADC sampling frequency/2, the cutoff frequency of the low-pass filter, and the signal frequency have such a vertical relationship. That is, as shown in FIG. 8(a), first, the signal 800 on which the influence of the coolant has been superimposed is passed through an analog filter 811 that adjusts the signal 800 on which the influence of the coolant has been superimposed to an extent that no aliasing noise occurs, taking into consideration the ADC sampling frequency. A signal 801 is input and converted from analog to digital by an ADC (analog-to-digital converter) 802 to obtain measurement information 803 before the digital signal filter. Subsequently, after filtering with a low-pass filter 804, post-digital signal filtering processing 805 is executed. In controlling such a functional block, the intermittent supply frequency is adjusted so that the intermittent supply frequency, the ADC sampling frequency/2, the low-pass filter cutoff frequency, and the signal frequency have a vertical relationship as shown in FIG. 8(b). and control the feed rate. Note that the filter 811 provided before the ADC can be omitted when the sampling frequency is high.

FIG. 9 is a waveform chart for explaining the effects of the first embodiment of the present invention, in which (a) is an analog waveform without coolant, (b) is a digital waveform without coolant, and (c) is a waveform diagram for explaining the effects of the first embodiment of the present invention. FIG. 10 is a diagram showing an analog waveform with coolant, (d) a digital waveform with coolant, and (e) a waveform passed through a digital low-pass filter with coolant. That is, in the first embodiment described above, by operating the apparatus and work table as shown in FIG. 5 using the control method described in connection with FIGS. 6 to 8, the control method shown in FIGS. A waveform as shown in (e) is obtained.

10, 20, 30, 40, 50 probing device,
12, 22, 32, 42, 52 feeding device,
14, 24, 34, 44, 54 probe,
16, 26, 36, 46, 56 stylus,
16a, 26a, 36a, 46a, 56a tip tip (tip ball),
17, 27, 37, 47, 57 work table,
18, 28, 38, 48, 58 work,
25, 35, 45 coolant supply device,
25a, 45a coolant nozzle,
49 Intermittent output air device,
49a Intermittent air blow nozzle,
59 arrow,

Claims (2)

A machine tool that is equipped with a probing device used to measure a workpiece and a coolant supply device, and the probing device has waterproof and/or oil-proof performance against coolant, and the signal level is converted into a digital signal instead of a binary signal. For devices equipped with a multi-step numerical conversion mechanism, the turbulent coolant flow is emitted toward the sensitivity direction of the probing device, superimposed on the output, and the digitally converted signal is filtered through a low-pass filter or band-pass filter. A method for operating a probing device in a machine tool, characterized in that quantization noise of a signal frequency component that can be filtered is reduced at low cost, and a portion of the probe device that comes in contact with a workpiece is also cleaned at the same time. A machine tool that is equipped with a probing device used for measuring a workpiece and a coolant supply device, and has waterproof and/or oil-proof performance for the probing device coolant, and has digital conversion to convert the signal level into a multi-level signal instead of a binary signal. For devices equipped with a mechanism for converting numerical values into stages, a coolant flow is intermittently radiated in the sensitive direction of the probing device, superimposed on the output, and the signal after digital conversion can be filtered with a low-pass filter or band-pass filter. A method for operating a probing device in a machine tool, characterized in that quantization noise of a desired signal frequency component is reduced at low cost, and a portion of the probe device that comes in contact with a workpiece is also cleaned at the same time.

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