Active measurement means that during the machining process, the measuring device always measures the size of the workpiece and transmits the dimensional change to the controller at any time. The signal is sent from the controller (such as rough grinding, fine grinding, light grinding, and Size and other signals) control the operation of the machine. Because it enables the operator to measure the workpiece without downtime, reducing labor intensity, increasing production efficiency, reducing scrap rate, and at the same time the consistency of workpiece size produced is higher, especially suitable for use in high-volume assembly line operations. Such as automotive parts, bearing parts processing.
1. The basic composition of the active meter
The active measuring instrument is mainly composed of a measuring device, a driving device, and a control device.
(1) Measuring device
During the process of grinding the workpiece by the grinding wheel, the two diamond measuring devices of the device always contact the surface of the workpiece, and the variation of the diameter of the workpiece passes through the tester and the lever, so that the positions of the magnetic core and the inductor coil in the device are relatively displaced, thereby the The change in size translates into a change in inductance. The active measuring device, commonly known as the probe, plays the role of converting the measured parameter's variation into the measuring signal. It is the main body of the measuring instrument. From the structural principle, it can be divided into single-point measuring device and double-point measuring device. The single-point measuring device can be used for positioning the end face or measuring the large diameter with two combinations; the double-point measuring device can measure the outer diameter, inner diameter, and groove Wide, wide steps and so on.
(2) Controller
The controller outputs the inductive signal of the device through the phase sensitive rectification and amplification, and sends signals such as rough grinding, fine grinding, light grinding, and size to the grinding machine control system. After the grinding machine control system receives the signal, it controls the feeding mechanism of the machine tool. Control the size of the workpiece.
The control instrument is an important part of the active measurement instrument. The current control instrument has basically eliminated the circuit of the separated element in the past, and has adopted the integrated circuit, and some of them have used the microprocessor, and have the performances of repeatability, long-term stability and the like. Greatly improved.
(3) Hydraulic Drive
The advance and retreat of the measuring device is driven by the hydraulic drive device. After the workpiece is installed, the grinding wheel advances quickly. At the same time, the drive cylinder also drives the active measurement device into the measurement station. After grinding to size, the grinding wheel is rapidly retracted, and the driving cylinder drives the active measuring device to exit the measuring station so that the operator can load and unload the workpiece.
The hydraulic driving device is the connecting part of the active measuring device and the machine tool. It is responsible for moving the device into or out of the measuring station. Through the adjustment of the front and rear fine adjustment mechanism, the contact of the device can be aligned with the center of the workpiece. Current cylinders are vertical and horizontal (as determined by the center height of the machine). Combining the active measurement control system composed of the above three parts with the machine tool control system forms an active measurement during the grinding process. Take the grinding process controlled by three signals as an example. From the grinding wheel to the rough grinding stage, P1 is the signal point for switching from rough grinding feed to fine grinding feed. P2 point is from the grinding feed There is no signal point for spark feed switching, and point P3 is the signal point for retraction. The machine tool control system receives these three signals from the controller successively to perform different actions and complete a grinding cycle. For high-precision grinding, the dimensional dispersion of machined parts can generally be controlled to 2 to 3 μm. In recent years, while the process requires an increase in dimensional accuracy, it is also necessary to increase the shape accuracy. The number of control signals required for this machine tool has been increased from 3 to 4, or even to 5 to 6 points.
2. Active measurement instrument control
(1) Control of workpiece taper
In the grinding of automotive parts, especially for workpieces with multiple shaft diameters, such as camshafts and crankshafts, the shaft diameter must be the same and large taper cannot be produced. Generally, two outer diameters are used for such workpieces. The device measures the shaft diameter at both ends, taking into account that the machining speed at both ends is not the same, and the control of the size and the taper is achieved by controlling the grinding cycle. The outer diameter measuring device controls the size of the two ends of the workpiece through the control device, and simultaneously outputs the measured taper value signal to the machine tool control system to control the action of the grinding wheel and complete the control of the taper of the workpiece.
(2) Measurement of workpiece ellipse
At present, there are two types of active gauges for measuring the ellipticity of shaft parts. The most common one is to use a two-point measuring device to directly measure the diameter of a workpiece and calculate the diameter difference through electrical calculation as the evaluation value of ellipticity. The other is the latest use of a single point measurement method in the process of detecting the workpiece roundness (with the roundness of the radius of the meter measuring principle is the same), by processing the measured data, directly read the workpiece Roundness value.
1 commonly used to measure the degree of elliptic active meter
Two-point measuring device: Built-in two differential transformer-type sensors for active measurement of shaft parts. The controller firstly controls the size of the shaft diameter. When the workpiece outside diameter grinding approaches the specified value, the controller begins to measure the ellipticity of the workpiece. The maximum and minimum diameters of the measured outside diameter are processed by the peak hold circuit and the data is directly output. The degree of ellipticity; if the ellipticity is too bad, it will send a signal to the machine to control the trimming of the ellipticity.
2 New on-line active measurement for roundness measurement
The use of the PULCOM V10 series controller from Tokyo Precision Co., Ltd., Japan, in combination with a two-point measuring device, enables the measurement of the workpiece diameter while using the same measuring principle as the radius method of the roundness meter to directly measure the workpiece with the lower contact of the device. Roundness. The meter's signal reflects the speed of 1ms, and the workpiece rotation speed is in the range of 17 to 999rpm. After one revolution, 60 to 3600 data can be measured. The roundness and crest value of the workpiece can be intuitively displayed on the screen. This controller can also select to measure the roundness value before or after the workpiece is machined to size. Compared with the traditional roundness meter measurement, it has the following advantages: it can reflect the roundness value of the workpiece at the processing site and reduce the labor load of the measurement room; it can play in time for some unexpected situations that affect the quality of the workpiece. Monitoring functions, such as poor workpiece top hole quality, rough part quality, residual crust when processed to size, failure of the grinding wheel feed system resulting in large deformation of the workpiece, etc.; can intuitively reflect the status of the machine running, This will shorten the equipment adjustment time and improve work efficiency.
3. Active meter application
With the rapid development of electronic technology, the application of new technologies marked by microcomputers has made great strides in the performance and function of active gauges. Modern active gauges have overcome the control of single dimensions and single processes in the past. Constraints, the requirements for product testing have become stricter and more comprehensive, and applications on the production line have become more widespread. It also puts forward higher standards for the function, accuracy and stability of the measuring instrument, and satisfies people's requirements for increasing product quality.
(1) Measurement before processing
The inner diameter measuring device 4 enters the measuring station by driving the cylinder 8 to measure the inner diameter of the workpiece 2 . Before grinding the grinding wheel, the measuring instrument has measured the inside diameter of the blank. If the size of the blank is too large or too small, the controller will send a signal to the machine to stop the feeding of the grinding wheel to avoid accidents.
(2) Measurement during processing
This is a common process for active measurement of grinding operations. This process is mainly to control the size of the workpiece. When the grinding wheel grinds the workpiece, as the size of the workpiece increases, the controller sends signals such as rough grinding, fine grinding, light grinding, and size to the machine according to the preset signal points, and the grinding wheel exits to complete grinding of the workpiece. process. In this example, most of the workpieces in a day have a size dispersion of 3 to 5 μm.
(3) Measurement after processing
After processing, the workpiece enters the machine to measure the working position. The inner diameter size of the workpiece is measured by the pneumatic probe, and the zero proof is automatically calibrated through the standard calibration gauge. The signal is output to the controller through the A/E gas-electric converter. The controller will be divided into five groups (+NG, +OK, OK, -OK, -NG) according to the size of the workpiece. At the same time, the trend of the dimensional change will be judged and issued to the controller 6 in the process according to the tendency of the size change. The signal is adjusted to make its zero position change and control the machining process to develop in a good direction. In this way, the machine tool can continue to work stably for long periods of unattended operation.
1. The basic composition of the active meter
The active measuring instrument is mainly composed of a measuring device, a driving device, and a control device.
(1) Measuring device
During the process of grinding the workpiece by the grinding wheel, the two diamond measuring devices of the device always contact the surface of the workpiece, and the variation of the diameter of the workpiece passes through the tester and the lever, so that the positions of the magnetic core and the inductor coil in the device are relatively displaced, thereby the The change in size translates into a change in inductance. The active measuring device, commonly known as the probe, plays the role of converting the measured parameter's variation into the measuring signal. It is the main body of the measuring instrument. From the structural principle, it can be divided into single-point measuring device and double-point measuring device. The single-point measuring device can be used for positioning the end face or measuring the large diameter with two combinations; the double-point measuring device can measure the outer diameter, inner diameter, and groove Wide, wide steps and so on.
(2) Controller
The controller outputs the inductive signal of the device through the phase sensitive rectification and amplification, and sends signals such as rough grinding, fine grinding, light grinding, and size to the grinding machine control system. After the grinding machine control system receives the signal, it controls the feeding mechanism of the machine tool. Control the size of the workpiece.
The control instrument is an important part of the active measurement instrument. The current control instrument has basically eliminated the circuit of the separated element in the past, and has adopted the integrated circuit, and some of them have used the microprocessor, and have the performances of repeatability, long-term stability and the like. Greatly improved.
(3) Hydraulic Drive
The advance and retreat of the measuring device is driven by the hydraulic drive device. After the workpiece is installed, the grinding wheel advances quickly. At the same time, the drive cylinder also drives the active measurement device into the measurement station. After grinding to size, the grinding wheel is rapidly retracted, and the driving cylinder drives the active measuring device to exit the measuring station so that the operator can load and unload the workpiece.
The hydraulic driving device is the connecting part of the active measuring device and the machine tool. It is responsible for moving the device into or out of the measuring station. Through the adjustment of the front and rear fine adjustment mechanism, the contact of the device can be aligned with the center of the workpiece. Current cylinders are vertical and horizontal (as determined by the center height of the machine). Combining the active measurement control system composed of the above three parts with the machine tool control system forms an active measurement during the grinding process. Take the grinding process controlled by three signals as an example. From the grinding wheel to the rough grinding stage, P1 is the signal point for switching from rough grinding feed to fine grinding feed. P2 point is from the grinding feed There is no signal point for spark feed switching, and point P3 is the signal point for retraction. The machine tool control system receives these three signals from the controller successively to perform different actions and complete a grinding cycle. For high-precision grinding, the dimensional dispersion of machined parts can generally be controlled to 2 to 3 μm. In recent years, while the process requires an increase in dimensional accuracy, it is also necessary to increase the shape accuracy. The number of control signals required for this machine tool has been increased from 3 to 4, or even to 5 to 6 points.
2. Active measurement instrument control
(1) Control of workpiece taper
In the grinding of automotive parts, especially for workpieces with multiple shaft diameters, such as camshafts and crankshafts, the shaft diameter must be the same and large taper cannot be produced. Generally, two outer diameters are used for such workpieces. The device measures the shaft diameter at both ends, taking into account that the machining speed at both ends is not the same, and the control of the size and the taper is achieved by controlling the grinding cycle. The outer diameter measuring device controls the size of the two ends of the workpiece through the control device, and simultaneously outputs the measured taper value signal to the machine tool control system to control the action of the grinding wheel and complete the control of the taper of the workpiece.
(2) Measurement of workpiece ellipse
At present, there are two types of active gauges for measuring the ellipticity of shaft parts. The most common one is to use a two-point measuring device to directly measure the diameter of a workpiece and calculate the diameter difference through electrical calculation as the evaluation value of ellipticity. The other is the latest use of a single point measurement method in the process of detecting the workpiece roundness (with the roundness of the radius of the meter measuring principle is the same), by processing the measured data, directly read the workpiece Roundness value.
1 commonly used to measure the degree of elliptic active meter
Two-point measuring device: Built-in two differential transformer-type sensors for active measurement of shaft parts. The controller firstly controls the size of the shaft diameter. When the workpiece outside diameter grinding approaches the specified value, the controller begins to measure the ellipticity of the workpiece. The maximum and minimum diameters of the measured outside diameter are processed by the peak hold circuit and the data is directly output. The degree of ellipticity; if the ellipticity is too bad, it will send a signal to the machine to control the trimming of the ellipticity.
2 New on-line active measurement for roundness measurement
The use of the PULCOM V10 series controller from Tokyo Precision Co., Ltd., Japan, in combination with a two-point measuring device, enables the measurement of the workpiece diameter while using the same measuring principle as the radius method of the roundness meter to directly measure the workpiece with the lower contact of the device. Roundness. The meter's signal reflects the speed of 1ms, and the workpiece rotation speed is in the range of 17 to 999rpm. After one revolution, 60 to 3600 data can be measured. The roundness and crest value of the workpiece can be intuitively displayed on the screen. This controller can also select to measure the roundness value before or after the workpiece is machined to size. Compared with the traditional roundness meter measurement, it has the following advantages: it can reflect the roundness value of the workpiece at the processing site and reduce the labor load of the measurement room; it can play in time for some unexpected situations that affect the quality of the workpiece. Monitoring functions, such as poor workpiece top hole quality, rough part quality, residual crust when processed to size, failure of the grinding wheel feed system resulting in large deformation of the workpiece, etc.; can intuitively reflect the status of the machine running, This will shorten the equipment adjustment time and improve work efficiency.
3. Active meter application
With the rapid development of electronic technology, the application of new technologies marked by microcomputers has made great strides in the performance and function of active gauges. Modern active gauges have overcome the control of single dimensions and single processes in the past. Constraints, the requirements for product testing have become stricter and more comprehensive, and applications on the production line have become more widespread. It also puts forward higher standards for the function, accuracy and stability of the measuring instrument, and satisfies people's requirements for increasing product quality.
(1) Measurement before processing
The inner diameter measuring device 4 enters the measuring station by driving the cylinder 8 to measure the inner diameter of the workpiece 2 . Before grinding the grinding wheel, the measuring instrument has measured the inside diameter of the blank. If the size of the blank is too large or too small, the controller will send a signal to the machine to stop the feeding of the grinding wheel to avoid accidents.
(2) Measurement during processing
This is a common process for active measurement of grinding operations. This process is mainly to control the size of the workpiece. When the grinding wheel grinds the workpiece, as the size of the workpiece increases, the controller sends signals such as rough grinding, fine grinding, light grinding, and size to the machine according to the preset signal points, and the grinding wheel exits to complete grinding of the workpiece. process. In this example, most of the workpieces in a day have a size dispersion of 3 to 5 μm.
(3) Measurement after processing
After processing, the workpiece enters the machine to measure the working position. The inner diameter size of the workpiece is measured by the pneumatic probe, and the zero proof is automatically calibrated through the standard calibration gauge. The signal is output to the controller through the A/E gas-electric converter. The controller will be divided into five groups (+NG, +OK, OK, -OK, -NG) according to the size of the workpiece. At the same time, the trend of the dimensional change will be judged and issued to the controller 6 in the process according to the tendency of the size change. The signal is adjusted to make its zero position change and control the machining process to develop in a good direction. In this way, the machine tool can continue to work stably for long periods of unattended operation.