Caliper calibration method based on linear motor module

Abstract

The invention provides a caliper calibration method based on a linear motor module. The method comprises the steps that a linear motor controls sliding of a sliding block to provide a calibration length; and two parts of the calibration positioning device are respectively arranged at the fixed end of the linear motor and the sliding block to realize linear contact with the caliper, so that calibration of the caliper is provided. Under the condition of the same difficulty, no other better caliper calibration method can realize the caliper calibration effects of low cost, high efficiency, high precision and any calibration point of the method provided by the invention at present.

Description

Technical Field

[0001] The invention belongs to the field of metrology, detection and calibration, and specifically relates to a method for realizing caliper calibration by utilizing a linear motor module through line contact. Background Art

[0002] Caliper is a kind of measuring tool, which is commonly divided into three categories: vernier caliper, dial caliper and digital caliper. It can be used to measure length, inner and outer diameter, inner and outer groove width, center distance, depth and other length dimensions, and has the function of measurement and inspection. Because of its reliable measurement, simple structure, easy use and maintenance, low price and other characteristics, caliper is the most common and widely used measuring tool in the machinery manufacturing industry. Its measurement performance is of great significance to product quality assurance.

[0003] The working principle of a caliper is to read the distance between the two measuring surfaces of its main scale and vernier scale. At present, the metrological calibration of calipers is carried out in a manner that conforms to its working principle during measurement. That is, a series of standard length dimensions (including internal and external dimensions) are measured using a caliper, and the measured caliper indication is compared with the standard length dimension to obtain the indication error of the caliper at the calibration point. During the calibration process, the standard length dimension is generally generated by a gauge block or a length measuring machine, and then the operator holds the caliper to perform a series of measurements. The entire calibration process has a low degree of automation, low calibration efficiency, and high metrological cost.

[0004] There are two main existing caliper calibration methods:

[0005] 1. Use gauge blocks to provide a range of standard lengths (see Figure 1 and Figure 2 ):

[0006] The gauge block is a standard end-face measuring tool without scales, which is made according to a certain value size. It is widely used in existing caliper calibration, that is, the two measuring faces of the caliper are in surface contact with the two end faces of the gauge block to implement the measurement. The advantage of this method is that the gauge block has high accuracy and high reproducibility of standard length dimensions. However, its disadvantage is that it can only measure the calibration points of the corresponding gauge block size, and it is impossible to measure the indication error of any calibration point according to requirements, and it can only provide standard external dimension length ( Figure 1 ), the calibration of the inner dimension indication error of the caliper requires the use of a special gauge to convert the outer dimension into the inner dimension (see Figure 2 ), the manual operation in this process is extremely cumbersome and inefficient. At the same time, the surface contact measurement method is not recommended in the optimization principle of geometric measurement. The defects of the contact surface further introduce certain measurement errors in the indication error calibration.

[0007] 2. Use a length measuring machine to provide a series of standard lengths (see Figure 3 ):

[0008] A length measuring machine is a length measuring instrument that uses a grating pitch, a linear scale scale, or a light wave wavelength as a known length and a mechanical probe for contact measurement. This method has been gradually applied to the field of caliper calibration in recent years. Its advantage is that it can produce any standard length, thereby meeting the measurement needs of the indication error of any calibration point. Its disadvantage is that the tailstock of the length measuring machine needs to be moved manually to produce a standard length dimension, and it cannot move automatically. Due to the high resolution of the instrument, it is difficult to find the right size in one go when determining a certain dimension. At the same time, the length measuring machine itself is very expensive, and the cost of using a length measuring machine to calibrate a caliper is very high. In fact, the grating measurement accuracy is much higher than the error transfer requirement for caliper calibration. From an economic point of view, it is not suitable for calibrating a caliper. Summary of the invention

[0009] In view of the above-mentioned status and problems existing in the prior art, the present invention provides a caliper calibration method based on a linear motor module. The core concept of the calibration method is to control the linear motor driver through PLC to form a servo drive mechanism, and use the linear motor to automatically generate any standard length displacement, so as to provide a standard length of any calibration position with sufficient accuracy for caliper calibration, thereby realizing a caliper calibration method with high efficiency, low cost, reliable accuracy and calibration at any point.

[0010] Specifically, the present invention provides a calibrator calibration method based on a linear motor module, the method comprising: providing a standard value of the calibration length by controlling the sliding of a slider by a linear motor; and achieving linear contact with the caliper by a calibration positioning device having two parts respectively arranged on a fixed end of the linear motor and a slider, thereby providing calibration of the caliper.

[0011] Furthermore, the caliper calibration method specifically includes the following steps:

[0012] Determine the calibration length;

[0013] The linear motor is driven by a controller so that a slider connected to a movable end of the linear motor slides along the guide rail;

[0014] The two parts of the calibration positioning device are respectively installed on the slider and the fixed end of the linear motor; the linear motor controls the slider to reach the desired position, and the distance L between the inner sides of the two parts of the calibration positioning device at the desired position or the distance L+2D between the outer sides of the two parts is the calibration length;

[0015] Bring the caliper into line contact with the inner or outer sides of the two parts of the calibration positioning device respectively;

[0016] Read the caliper display value A 内 or A 外 ;

[0017] Compare the caliper display to the calibration length to determine the calibration error and calibrate the caliper to that calibration length.

[0018] The calibration and positioning device is two precision pin-type plug gauges. Before the linear motor is started, the two plug gauges of the calibration and positioning device are preferably contacted and zeroed.

[0019] Furthermore, the diameters of the two precision pin-type plug gauges are the same, the dimensional deviation does not exceed ±0.001mm, and the generatrix straightness does not exceed 0.001mm. There is no special range for the diameter D of the plug gauge here, as long as the diameter is the same and the accuracy meets the standard. Generally speaking, although it is convenient to measure if the diameter is too small, the plug gauge has low rigidity and is prone to deformation, which affects the measurement results; and if the diameter is too large, it is not convenient to install. Therefore, in practical applications, a plug gauge with a diameter D range of 1-5mm can be used, preferably 5mm.

[0020] The distance L between the inner sides of the two parts of the calibration positioning device is measured by a sensor and fed back to the controller.

[0021] When measuring the outer dimension indication error of the caliper, make the outer jaws contact the outer generatrix of the calibration positioning device and read the caliper indication A. 外 , then the error of the external claw indication at this point is: E 外 =A 外 -L-2D.

[0022] When measuring the inner dimension indication error of the caliper, make the inner jaw contact the inner generatrix of the calibration positioning device and read the caliper indication A. 内 , then the error of the external claw indication at this point is: E 内 =A 内 -L.

[0023] At the same time, a caliper calibration system of the calibration method of the present invention is also provided, which mainly includes: a controller, a linear motor, a sensor, a guide rail, a slider and a calibration positioning device.

[0024] Specifically, the controller, preferably a PLC programmable controller, is used to control the motion of the linear motor. The current and voltage generated by the controller can control the position, speed, acceleration and other parameters of the linear motor.

[0025] The linear motor is the core part of the system. Its working principle is realized by electromagnetic principle and it is responsible for providing driving force. The system preferably adopts an iron core linear motor, which is a transmission device that can directly convert electrical energy into mechanical energy and generate linear motion without any intermediate conversion mechanism. The linear motor has two important parts: a stator and a moving part. The stator is composed of an iron core and a coil, and current is provided by a power supply to generate a magnetic field. The moving part is composed of a magnet and a conductor. When the stator generates a magnetic field, the moving part moves under the action of the magnetic force. The movement direction of the linear motor module is related to the direction of the stator coil. When the current is reversed, the movement direction of the moving part will also be reversed. The moving part is used to connect the slider to provide power for the slider. The linear motor used in the present invention has the advantages of simple structure, convenient long stroke, high acceleration, fast response and high precision. The positioning accuracy can reach ±0.001mm at most, and the repeat positioning accuracy can reach 0.001mm.

[0026] The sensor is used to detect the position, speed, acceleration and other parameters of the linear motor, and feed these parameters back to the controller for control. This system uses an encoder for position feedback to achieve high-precision position control. In addition, the controller can achieve different movement speeds and accelerations by changing the magnitude and direction of the current.

[0027] The slider is the moving part of this system. Its main function is to cooperate with the guide rail to achieve linear motion. The distance between its movement and the fixed end of the linear motor is the standard length dimension (i.e., calibration length) provided by the system. There are multiple mounting holes above the slider and the fixed end of the motor for installing the calibration positioning device.

[0028] The main function of the guide rail in this system is to support and guide the movement of the slider. The preferred material is GCr15 steel, which has good rigidity and wear resistance, providing reliable and stable movement assistance for the slider. The guide rail is precision ground with a straightness of 0.003mm to ensure calibration accuracy.

[0029] The calibration positioning device is a component that makes line contact with the caliper measuring surface. This system uses a pair of first-level precision pin-type plug gauges of the same diameter, whose dimensional deviation does not exceed ±0.001mm and the generatrix straightness does not exceed 0.001mm. They are installed in the mounting holes of the slider and the motor fixed end respectively through tight fit.

[0030] The advantages of the present invention are as follows: (1) The application of the linear motor module in the field of caliper calibration is a brand-new design, which can automatically generate any standard length through the control system, solve the problem of calibration of indication error of any calibration point, meet the requirements of calibrator calibration in special occasions, and combine the low cost, low energy consumption, high accuracy and other characteristics of the linear motor module with the field of geometric measurement, thus saving costs;

[0031] (2) The standard length is automatically generated through the linear motor, and the operation speed is fast, the positioning is accurate and reliable, which reduces the tedious manual operations and greatly improves the efficiency;

[0032] (3) The contact method for caliper calibration is designed to be line contact, which is more in line with the contact method optimization principle in geometric measurement than the current surface contact method, reduces the measurement error introduced by contact defects in the indication error calibration, and improves the measurement accuracy.

[0033] Under the same difficulty conditions, there is currently no other better calibrator calibration method that can achieve the low-cost, high-efficiency, high-precision, and calibrator calibration effects of the method provided by the present invention at any calibration point. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a schematic diagram of the principle of using a gauge block to realize external dimension measurement and calibration in the prior art.

[0035] Figure 2 It is a schematic diagram of the principle of using a gauge block to achieve internal dimension measurement and calibration in the prior art (with the help of a special inspection fixture).

[0036] Figure 3 The present invention is a schematic diagram of the principle of using a length measuring machine to calibrate a caliper in the prior art.

[0037] Figure 4 It is a three-dimensional display schematic diagram of a calibration system including a linear motor module used in a caliper calibration method based on a linear motor module of the present invention.

[0038] Figure 5 yes Figure 4 A top view of a calibration system including a linear motor module used in a calibrator calibration method based on a linear motor module of the present invention is shown.

[0039] Figure 6 yes Figure 4 A side view of a calibration system including a linear motor module used in a caliper calibration method based on a linear motor module of the present invention is shown.

[0040] Figure 7 yes Figure 4 Schematic diagram of the guide rails in the system shown.

[0041] Figure 8 yes Figure 4 Schematic diagram of the calibration positioning device in the system shown.

[0042] Fig. 9 It is a schematic diagram of measuring the indication error of the outer dimension of a caliper in a caliper calibration method based on a linear motor module of the present invention.

[0043] Fig.10 It is a schematic diagram of measuring the indication error of the inner dimension of the caliper in a caliper calibration method based on a linear motor module of the present invention.

[0044] In the figure, 1. linear motor; 2. sensor; 3. controller; 4. slider; 5. slide rail; 6. calibration positioning device; 11. fixed end; 12. mounting hole; 13. plug gauge. DETAILED DESCRIPTION

[0045] The "caliper calibration method based on linear motor module" of the present invention is further explained in conjunction with the accompanying drawings.

[0046] See also Figure 4-10 The present invention provides a caliper calibration method based on a linear motor module, the method comprising:

[0047] Determine the calibration length L or L+2D;

[0048] The linear motor 1 is driven by the controller 3 so that the slider 4 connected to the movable end of the linear motor 1 slides along the guide rail 5, thereby separating the two plug gauges 13 that are in contact and set to zero;

[0049] The two plug gauges 13 of the calibration positioning device 6 are respectively installed on the slider 4 and the fixed end 11 of the linear motor 1; the linear motor 1 controls the slider 4 to reach the desired position, and the distance L between the inner sides or the distance L+2D between the outer sides of the two plug gauges 13 of the calibration positioning device 6 at the desired position is the calibration length;

[0050] The caliper is brought into line contact with the inner side or the outer side of the two plug gauges 13 of the calibration positioning device 6;

[0051] Read the caliper display value A 内 or A 外 ;

[0052] Set the caliper display value to A 内 or A 外 Compare with the calibration length L or L+2D to determine the calibration error and calibrate the caliper to this calibration length.

[0053] In this example, the calibration and positioning device 6 is a pair of first-class precision pin-type plug gauges 13 of the same diameter (see Figure 4 , Figure 5-6 The size deviation is not shown in the figure, and the busbar straightness is not more than 0.001mm. It is installed in the mounting hole 12 of the slider 4 and the motor fixed end 11 respectively by tight fit.

[0054] Meanwhile, the caliper calibration system for implementing the calibration method mainly includes: a controller 3 , a linear motor 1 , a sensor 2 , a guide rail 5 , a slider 4 and a calibration positioning device 6 .

[0055] The linear motor 1 preferably adopts an iron core linear motor to generate linear motion. Under the action of the magnetic field, the moving part of the motor drives the slider 4 to move linearly to obtain the required distance / length L. The linear motor used in the present invention has the advantages of simple structure, convenient long stroke, high acceleration, fast response, high precision, and the highest positioning accuracy can reach ±0.001mm, and the repeat positioning accuracy can reach 0.001mm.

[0056] The controller 3 may preferably be a PLC programmable controller. The current and voltage generated by the controller 3 may control parameters such as the position, speed, and acceleration of the linear motor 1 .

[0057] The sensor 2 is used to detect the position, speed, acceleration and other parameters of the linear motor 1, and feed these parameters back to the controller 3 for control. The system uses an encoder for position feedback to achieve high-precision position control.

[0058] The slider 4 is the moving part of the system, and its main function is to cooperate with the guide rail 5 to achieve linear motion. The distance L generated by its movement and the fixed end 11 of the linear motor 1 is the standard length dimension (i.e., the calibration length) provided by the system. There are multiple mounting holes 12 above the slider 4 and the fixed end 11 of the motor for installing the calibration positioning device 6. The proximal mounting hole 12 is preferably used for calibrator calibration so that the plug gauge 13 can be contacted and zeroed; the distal and other mounting holes can be used as extended applications, for example, by using the high load capacity of the linear motor and installing a force sensor, a mechanical tensile test of the material can be performed.

[0059] The main function of the guide rail 5 in this system is to support and guide the movement of the slider 4. The preferred material is GCr15 steel, which has good rigidity and wear resistance and provides reliable and stable movement assistance for the slider 4. The guide rail 5 is precisely ground with a straightness of 0.003mm to ensure calibration accuracy.

[0060] When calibrating the caliper, when the two calibration positioning devices 6 (both with diameters D) are in contact, this position is set as the zero point. When calibrating the indication error of point A of the caliper, the controller 3 sets the running distance L of the linear motor 1 so that L=A, and the slider 4 moves to produce the standard length dimension.

[0061] When the slide block 4 completes its movement, the caliper measuring surface contacts the calibration positioning device 6:

[0062] ① When measuring the indication error of the caliper's external dimensions, if Fig. 9 As shown, make the outer jaw contact with the outer generatrix of the plug gauge 13 of the positioning device 6, and read the caliper indication A 外 , then the error of the external claw indication at this point is: E 外 =A 外-L-2D

[0063] ② When measuring the error of the caliper's internal dimension indication, if Fig.10 As shown, the inner measuring claw is brought into contact with the inner generatrix of the plug gauge 13 of the positioning device 6, and the caliper indication A is read. 内 , then the error of the external claw indication at this point is: E 内 =A 内 -L.

[0064] As mentioned above, the current caliper calibration method has more or less problems such as inability to measure arbitrary calibration points, low measurement efficiency, high measurement cost, and limited measurement accuracy. Moreover, it cannot simultaneously achieve the four requirements of arbitrary calibration point measurement, high efficiency, low cost, and high accuracy.

[0065] However, the caliper calibration method based on linear motor module proposed in this paper: ① Applying linear motor module to the field of caliper calibration is a brand-new design, which can automatically generate any standard length through the control system, solves the problem of calibration of indication error of any calibration point, meets the requirements of calibrator calibration in special occasions, and combines the low cost, low energy consumption and high accuracy of linear motor module with the field of geometric measurement to save costs; ② The standard length is automatically generated by linear motor, and the running speed is fast, the positioning is accurate and reliable, which reduces the tedious manual operations and greatly improves the efficiency; ③ The contact mode of caliper calibration is designed as line contact, which is more in line with the contact mode optimization principle in geometric measurement than the current surface contact mode, reduces the measurement error introduced by contact defects in indication error calibration, and improves the measurement accuracy.

[0066] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A caliper calibration method based on a linear motor module, characterized in that: The method comprises: providing a calibration length by controlling the sliding of a slider by a linear motor; and achieving line contact with a caliper by a calibration positioning device having two parts respectively arranged on a fixed end of the linear motor and on the slider, thereby providing calibration of the caliper.

2. A caliper calibration method based on a linear motor module according to claim 1, characterized in that: The method specifically comprises the following steps: Determine the calibration length; The linear motor is driven by a controller so that a slider connected to a movable end of the linear motor slides along a guide rail; The two parts of the calibration positioning device are respectively installed on the slider and the fixed end of the linear motor; the linear motor controls the slider to reach the desired position, and the distance L between the inner sides of the two parts of the calibration positioning device or the distance L+2D between the outer sides of the two parts at the desired position is the calibration length; Bringing the caliper into line contact with the inner side or the outer side of the two parts of the calibration positioning device respectively; Read the caliper display value A 内 or A 外 ; Compare the caliper display to the calibration length to determine the calibration error and calibrate the caliper to that calibration length.

3. A caliper calibration method based on a linear motor module according to claim 1 or 2, characterized in that: The calibration and positioning device is two precision pin-type plug gauges.

4. A caliper calibration method based on a linear motor module according to claim 3, characterized in that: The two precision pin-type plug gauges have the same diameter, a dimensional deviation of no more than ±0.001 mm, and a generatrix straightness of no more than 0.001 mm.

5. A caliper calibration method based on a linear motor module according to any one of claims 1 to 4, characterized in that: The distance L between the inner sides of the two parts of the calibration positioning device is measured by a sensor and fed back to the controller.

6. A caliper calibration method based on a linear motor module according to any one of claims 1 to 5, characterized in that: When measuring the outer dimension indication error of the caliper, the outer jaw is brought into contact with the outer generatrix of the calibration positioning device, and the caliper indication A is read. 外 , then the error of the external claw indication at this point is: E 外 =A 外 -L-2D.

7. A caliper calibration method based on a linear motor module according to any one of claims 1 to 5, characterized in that: When measuring the inner dimension indication error of the caliper, the inner measuring jaw is brought into contact with the inner generatrix of the calibration positioning device, and the caliper indication A is read. 内 , then the error of the external claw indication at this point is: E 内 =A 内 -L.

Images