Closed-loop force control size measuring device and measuring method

Abstract

The invention provides a closed-loop force-controlled size measuring device and method, the measuring device comprises a fixing frame, a force sensor, an object placing table and a pressing plate, the inner bottom side of the fixing frame is provided with a first vertical moving mechanism, the first vertical moving mechanism comprises a moving part and a fixing part connected with the fixing frame, and the fixing part is provided with a second vertical moving mechanism. The moving part can reciprocate relative to the fixed part in the vertical direction, and the storage table is connected with the moving part; a second vertical moving mechanism connected with the pressing plate is arranged on the inner top side of the fixing frame, and the second vertical moving mechanism can drive the pressing plate to reciprocate in the vertical direction; the force sensor is arranged at the bottom end of the first vertical moving mechanism, the fixed end of the force sensor is connected with the fixed frame, and the force bearing end of the force sensor is connected with the moving part. According to the invention, the first vertical moving mechanism can bear bending moment generated due to the fact that the workpiece to be measured is biased on the object placing table, it is ensured that the force sensor is only subjected to vertical pressure, and the force control precision can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soft workpiece size measurement, in particular to a closed-loop force control size measurement device and a measurement method. BACKGROUND

[0002] In the scenario of measuring the size of a soft workpiece, the measured workpiece will be deformed when pressed, so it is understandable that if the measured workpiece is measured under different pressures, the size measurement results will be inconsistent. Therefore, the measured workpiece is usually measured under a certain determined pressure.

[0003] Usually, the measuring device needs to control the pressure of its extension mechanism to achieve measurement under a certain pressure. The commonly used force control method includes weight counterforce control. Although this method has a great cost advantage, the force is unstable due to the uncertain wear state of the transmission mechanism of the extension mechanism, that is, the precision of the force cannot be completely controlled by the weight alone. In addition, the use of weights will cause the weight effect, which is likely to cause the peak force to far exceed the weight of the weight, resulting in poor precision of the measurement result. Moreover, it is not convenient to change different forces, and there is an urgent need for a measuring device that can guarantee the precision of force control. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a closed-loop force control size measurement device and a measurement method, and to provide a measuring device that can guarantee the precision of force control, and to solve the problem that the existing weight counterforce control cannot completely control the precision of the force, resulting in poor precision of the measurement result.

[0005] In order to solve the above technical problems, the technical solution used by the present application is: On the one hand, the closed-loop force control size measurement device of the present application comprises a fixed frame, a force sensor, a workpiece placing table and a pressing plate. The inner bottom side of the fixed frame is provided with a first vertical movement mechanism, the first vertical movement mechanism comprises a moving part and a fixed part connected with the fixed frame, the moving part can reciprocate along the vertical direction relative to the fixed part, and the workpiece placing table is connected with the moving part. The inner top side of the fixed frame is provided with a second vertical movement mechanism, the pressing plate is connected with the second vertical movement mechanism, the pressing plate is located above the workpiece placing table and is arranged face to face with the workpiece placing table, and the second vertical movement mechanism can drive the pressing plate to reciprocate along the vertical direction to approach or move away from the workpiece placing table. The force sensor is arranged at the bottom end of the first vertical movement mechanism, the fixed end of the force sensor is connected with the fixed frame, and the force-bearing end of the force sensor is connected with the moving part.

[0006] Preferably, it further comprises a first reading device, the first reading device is connected with the first vertical movement mechanism, and is used for measuring the deformation amount of the force sensor.

[0007] Further preferably, the first reading device is a grating displacement sensor, a reading head of the grating displacement sensor is fixed to the fixed part, and a grating ruler of the grating displacement sensor is fixed to the moving part.

[0008] Preferably, a first connecting block is arranged on the inner bottom of the fixed frame, the first connecting block is located below the first vertical moving mechanism, and the fixed part and the fixed end of the force sensor are fixed on the first connecting block, respectively.

[0009] Preferably, the first vertical moving mechanism comprises a first sliding assembly, the first sliding assembly comprises a first fixed part and a first sliding part in sliding connection with the first fixed part, the moving part is connected with the first sliding part, and the fixed part is fixed to the fixed frame and connected with the first fixed part.

[0010] Further preferably, the first sliding assembly is a cross roller guide.

[0011] Preferably, the second vertical moving mechanism comprises a second sliding assembly, a driving device and an extension head, the second sliding assembly comprises a second fixed part and a second sliding part in sliding connection with the second fixed part, the second fixed part is connected with the fixed frame, the second sliding part is connected with the pressing plate through the extension head, and the driving device is connected with the fixed frame at one end and connected with the extension head at the other end to drive the pressing plate to move reciprocatingly along the vertical direction.

[0012] Further preferably, the second vertical moving mechanism further comprises a second reading device, the second reading device is connected with the second sliding assembly and used for measuring the displacement of the extension head. Or, the second vertical moving mechanism further comprises a grating displacement sensor, a reading head of the grating displacement sensor is fixed to the second fixed part, and a grating ruler of the grating displacement sensor is fixed to the second sliding part. And / or, the second sliding assembly is a cross roller guide.

[0013] Further preferably, the driving device comprises a control board and a linear motor in electrical connection with the control board, the control board and a stator of the linear motor are connected with the fixed frame, respectively, and a rotor of the linear motor is connected with the extension head. And / or, the driving device comprises a control board and a linear motor in electrical connection with the control board, the control board and a stator of the linear motor are connected with the fixed frame, respectively, and a rotor of the linear motor is connected with the extension head.

[0014] In another aspect, the size measuring method comprises the following steps: Place the calibration weight on the placing table, pressure calibrate the force sensor, and take out the calibration weight; Place the standard block with the size of T 0 on the placing table, and use the first vertical moving mechanism to make the lower surface of the pressing plate close to the upper surface of the standard block; read the pressure value of the force sensor P 1 , obtain the displacement of the pressing plate A 1 and the deformation of the force sensor B 1 , and take out the standard block; Place the workpiece to be measured on the placing table, and use the first vertical moving mechanism to make the lower surface of the pressing plate close to the upper surface of the workpiece to be measured at the pressure value P 1 ; obtain the displacement of the pressing plate A 2 and the deformation of the force sensor B 2 ; Calculate the size of the workpiece to be measured T = T 0 + ( A 1 - A 2 ) + ( B 1 - B 2 ).

[0015] The beneficial effects of the closed-loop force control size measuring device according to the present application mainly include: The first vertical moving mechanism can control the placing table and the second vertical moving mechanism can control the pressing plate to move only in the vertical direction, respectively, the first vertical moving mechanism can withstand the bending moment generated by the workpiece to be measured offset on the placing table, so that the force sensor only receives the vertical pressure, avoids the reduction of force control accuracy and measurement accuracy caused by the bending moment, and further improves the force control accuracy and promotes the improvement of the measurement accuracy; The force sensor is arranged at the bottom end of the first vertical moving mechanism, the fixed end of the force sensor is connected with the fixed frame, and the force receiving end of the force sensor is connected with the moving part, so that the force closed-loop control can be realized, and the influence of external mechanical changes on the force control can be adapted.

[0016] The beneficial effects of the size measuring method according to the present application mainly include: The method is simple in operation, the closed-loop force control size measuring device is adopted, precision force control can be achieved, and the measurement result has high precision. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present application are shown by way of illustrative example. Like reference numerals in the drawings denote like elements, and the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the present application. The drawings illustrate the principles of the present application. In fact, the drawings show but a few of the myriad of possibilities supported by this application.

[0018] Figure 1 A perspective view of a closed-loop force control size measuring device according to an embodiment of the present application; Figure 2 A perspective view of a closed-loop force control size measuring device according to an embodiment of the present application; Figure 3 A front view of a closed-loop force control size measuring device according to an embodiment of the present application; Figure 1 A front view of a closed-loop force control size measuring device according to an embodiment of the present application; Figure 4 A front view of a closed-loop force control size measuring device according to an embodiment of the present application; BRIEF DESCRIPTION OF DRAWINGS First vertical moving mechanism 100, moving part 110, fixed part 120, first sliding part 130, first fixed part 140; Second vertical moving mechanism 200, second sliding part 210, second fixed part 220, extension head 230, linear motor 240; Fixed frame 300, bottom plate 310, side plate 320, top plate 330; Force sensor 1, object placing table 2, pressing plate 3, first connecting block 4, first reading device 5, second reading device 6, magnetic force spring 7. DETAILED DESCRIPTION

[0019] The technical solutions of the present application will be further described in detail below in combination with the drawings and specific embodiments, so that those skilled in the art can better understand the present application and implement it. However, the embodiments are not intended to limit the present application. In the embodiments, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used for the purpose of describing the present application, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0020] It is to be noted that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements can be present. The terms "mounted", "one end", "the other end" and the like as used herein are intended to mean for the purpose of illustration and description only.

[0021] The embodiment provides a closed-loop force control size measuring device, as shown in the drawings, which comprises a fixing frame 300, a force sensor 1, a workbench 2 and a pressing plate 3. Figures 1 to 4 As shown in the drawings, the fixing frame 300 is internally provided with a first vertical moving mechanism 100, the first vertical moving mechanism 100 comprises a moving part 110 and a fixed part 120 connected with the fixing frame 300, the moving part 110 can reciprocate along the vertical direction relative to the fixed part 120, and the workbench 2 is connected with the moving part 110; the fixing frame 300 is internally provided with a second vertical moving mechanism 200, the pressing plate 3 is connected with the second vertical moving mechanism 200, the pressing plate 3 is arranged above the workbench 2 and faces the workbench 2, and the second vertical moving mechanism 200 can drive the pressing plate 3 to reciprocate along the vertical direction to approach or move away from the workbench 2. The force sensor 1 is arranged at the bottom end of the first vertical moving mechanism 100, the fixed end of the force sensor 1 is connected with the fixing frame 300, and the force-bearing end of the force sensor 1 is connected with the moving part 110.

[0022] The first vertical moving mechanism 100 and the second vertical moving mechanism 200 are arranged, the first vertical moving mechanism 100 can control the workbench 2 to move along the vertical direction only, the second vertical moving mechanism 200 can control the pressing plate 3 to move along the vertical direction only, the first vertical moving mechanism 100 can bear the bending moment generated due to the offset of the workpiece to be measured on the workbench 2, the force sensor 1 is guaranteed to only bear the vertical pressure, the reduction of force control precision and measurement precision caused by the bending moment is avoided, the force control precision is improved, and the measurement precision is improved. The force sensor 1 is arranged at the bottom end of the first vertical moving mechanism 100, the fixed end of the force sensor 1 is connected with the fixing frame 300, and the force-bearing end of the force sensor 1 is connected with the moving part 110.

[0023] In order to guarantee the structural rigidity and stability of the measuring device, the fixing frame 300 preferably adopts a detachable plate type assembly structure, which can guarantee the structural stability of the fixing frame 300 and facilitate the disassembly and assembly of other components of the measuring device. Meanwhile, the plate type structure can be subjected to weight reduction treatment by using lightening holes and other lightening technical means. Figure 1 In the embodiment shown, the fixing frame 300 comprises a bottom plate 310, a side plate 320 and a top plate 330, the workbench 2 is preferably made of marble or ceramic material with a molecular structure which is more stable. The force sensor 1 is preferably arranged directly below the workbench 2.

[0024] In a preferred embodiment, the first connecting block 4 is arranged on the bottom of the fixed frame 300, and the fixed part 120 and the fixed end of the force sensor 1 are fixed on the first connecting block 4. By fixing the fixed part 120 of the first vertical moving mechanism 100 and the fixed end of the force sensor 1 on the first connecting block 4, the interference of the external environment on the first vertical moving mechanism 100 and the force sensor 1 can be reduced, and the stability of the fixed part 120 and the force sensor 1 can be improved. The first connecting block 4 can be detachably fixed on the fixed frame 300.

[0025] In another preferred embodiment, the closed-loop force control size measuring device further comprises a first reading device 5 connected with the first vertical moving mechanism 100, which is used to measure the deformation of the force sensor 1, i.e. the displacement of the placement table 2. As an example, the first reading device 5 is a grating displacement sensor, the reading head of which is fixed on the fixed part 120, and the grating ruler of which is fixed on the moving part 110. When the moving part 110 moves vertically relative to the fixed part 120, the grating ruler can be driven to move synchronously, and then the reading head can read the grating ruler to obtain the displacement of the moving part 110. The data of the grating ruler can also be used to evaluate whether the force sensor 1 is normal.

[0026] In another preferred embodiment, the first vertical moving mechanism 100 comprises a first sliding assembly, which comprises a first fixed part 140 and a first sliding part 130 slidingly connected with the first fixed part 140, the moving part 110 is connected with the first sliding part 130, and the fixed part 120 is fixed on the fixed frame 300 and connected with the first fixed part 140.

[0027] The first fixed part 140 and the first sliding part 130 can be a structure cooperating with the principle of a sliding block and a sliding rail, so that the first sliding part 130 is directly connected with the fixed part 120, reducing the intermediate transmission links, which can reduce the friction and structural wear, and is conducive to realizing precision force control and ensuring measurement accuracy. As one of the preferred embodiments, the first sliding assembly is a cross roller guide, which has the dual advantages of high precision and high hardness, and can not only meet the requirement of bearing bending moment, but also ensure high precision requirement due to its rigidity. In this embodiment, the fixed part 120 is a concave block component, and the moving part 110 is arranged in the groove space of the fixed part 120. Cross roller guides facing the moving part 110 are symmetrically arranged on both sides of the fixed part 120, and then one of the tracks of each cross roller guide is connected with the fixed part 120, and the other track is connected with the moving part 110.

[0028] In another preferred embodiment, the second vertical moving mechanism 200 comprises a second sliding assembly, a driving device and an extension head 230, the second sliding assembly comprises a second fixed part 220 and a second sliding part 210 which is in sliding connection with the second fixed part 220, the second fixed part 220 is connected with the fixed frame 300, the second sliding part 210 is connected with the pressing plate 3 through the extension head 230, the driving device is connected with the fixed frame 300 at one end and connected with the extension head 230 at the other end to drive the pressing plate 3 to move vertically and reciprocally. The second sliding assembly is preferably a cross roller guide, that is, the second fixed part 220 and the second sliding part 210 constitute two relatively slidable tracks of the cross roller guide.

[0029] Further preferably, the second vertical moving mechanism 200 further comprises a second reading device 6 which is connected with the aforementioned second sliding assembly and is used to measure the displacement of the extension head 230; Alternatively, the second vertical moving mechanism 200 further comprises a grating displacement sensor, the reading head of the grating displacement sensor is fixed on the second fixed part 220, and the grating ruler of the grating displacement sensor is fixed on the second sliding part 210, and the principle is as described above, which will not be repeated here.

[0030] Further preferably, the driving device comprises a control board (not shown in the figure) and a linear motor 240 which is electrically connected with the control board, the control board and the stator of the linear motor 240 are connected with the fixed frame 300 respectively, and the rotor of the linear motor 240 is connected with the extension head 230. Compared with the complex transmission mechanism which has different degrees of wear or deformation during long-term use, the driving device of the present embodiment is of the motor driving type, and the stability and precision of motor control displacement are better, and it has good reliability and repeatability.

[0031] Further preferably, the second vertical moving mechanism 200 further comprises an elastic protection arm, the upper end of the elastic protection arm is connected with the fixed frame 300, the lower end of the elastic protection arm is connected with the extension head 230, and the lower end of the elastic protection arm can elastically stretch and contract relative to the upper end. The lower end of the elastic protection arm can stretch and contract following the up-and-down movement of the extension head 230, thereby preventing the extension head 230 from abnormally falling and crushing the measured workpiece. In the present embodiment, the elastic protection arm is selected to be a magnetic spring 7, and other damping, tension springs can also be selected.

[0032] On the other hand, based on the above-mentioned closed-loop force control size measuring device, a size measuring method is provided, comprising the steps of: placing the calibration weight on the worktable 2, calibrating the pressure of the force sensor 1, and taking out the calibration weight; placing a standard block with a size of T 0 on the worktable 2, using the first vertical moving mechanism 100 to press the lower surface of the pressing plate 3 against the upper surface of the standard block; reading the pressure value of the force sensor 1P 1 , the displacement of the pressing plate 3 A 1 and the deformation of the force sensor 1 B 1 , the standard block is taken out; through this step, the installation distance between the worktable 2 and the pressing plate 3 can be calibrated, and the influence of the installation and structural errors of the measuring device itself on the measurement result can be eliminated; the workpiece to be measured is placed on the worktable 2, and the lower surface of the pressing plate 3 is pressed against the upper surface of the workpiece to be measured by the first vertical moving mechanism 100 at a pressure value P 1 ; the displacement of the pressing plate 3 is obtained A 2 and the deformation of the force sensor 1 B 2 ; the size of the workpiece to be measured is calculated T = T 0 + ( A 1 - A 2 ) + ( B 1 - B 2 ).

[0033] The method of the embodiment is simple in operation, and the precision force control can be achieved and the measurement result has high precision, because the closed-loop force control size measuring device is used.

[0034] It should be noted that whether the force control is accurate can be determined by judging B 1 and B 2 whether they are close to each other, and if B 1 and B 2 have a large difference, it can be determined that the force sensor 1 has a fault.

[0035] In this specification, unless specifically stated and limited otherwise, the first feature is "on", "above" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be directly above or obliquely above the second feature, or it can only mean that the horizontal height of the first feature is higher than that of the second feature. The first feature can be directly below or obliquely below the second feature, or it can only mean that the horizontal height of the first feature is lower than that of the second feature.

[0036] In the description of the specification, the description using the terms "preferred embodiment", "still another embodiment", "other embodiments", "specific example" or the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative expressions of the above terms are not necessarily directed to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in an appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples, without contradiction.

[0037] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A closed-loop force-controlled dimension measuring device, characterized in that: The device includes a fixed frame, a force sensor, a storage platform, and a pressure plate. A first vertical moving mechanism is provided on the bottom inner side of the fixed frame. The first vertical moving mechanism includes a moving part and a fixed part connected to the fixed frame. The moving part can reciprocate vertically relative to the fixed part, and the storage platform is connected to the moving part. A second vertical moving mechanism is provided on the top inner side of the fixed frame. The pressure plate is connected to the second vertical moving mechanism and is located above the storage platform, facing it. The second vertical moving mechanism can drive the pressure plate to reciprocate vertically, moving it closer to or away from the storage platform. The force sensor is disposed at the bottom end of the first vertical moving mechanism, the fixed end of the force sensor is connected to the fixed frame, and the force-bearing end of the force sensor is connected to the moving part.

2. The closed-loop force-controlled dimension measuring device according to claim 1, characterized in that: It also includes a first reading device, which is connected to the first vertical moving mechanism, for measuring the deformation of the force sensor.

3. The closed-loop force-controlled dimension measuring device according to claim 2, characterized in that: The first reading device is a grating displacement sensor, the reading head of the grating displacement sensor is fixed to the fixed part, and the grating ruler of the grating displacement sensor is fixed to the moving part.

4. The closed-loop force-controlled dimension measuring device according to claim 1, characterized in that: The inner bottom of the fixed frame is provided with a first connecting block, which is located below the first vertical moving mechanism. The fixed part and the fixed end of the force sensor are respectively fixed on the first connecting block.

5. The closed-loop force-controlled dimension measuring device according to claim 1, characterized in that: The first vertical moving mechanism includes a first sliding component, which includes a first fixing member and a first sliding member slidably connected to the first fixing member. The moving part is connected to the first sliding member, and the fixing part is fixed to the fixing frame and connected to the first fixing member.

6. The closed-loop force-controlled dimension measuring device according to claim 5, characterized in that: The first sliding component is a cross roller guide.

7. The closed-loop force-controlled dimension measuring device according to claim 1, characterized in that: The second vertical moving mechanism includes a second sliding component, a driving device, and an extension head. The second sliding component includes a second fixing member and a second sliding member slidably connected to the second fixing member. The second fixing member is connected to the fixing frame, and the second sliding member is connected to the pressure plate through the extension head. One end of the driving device is connected to the fixing frame, and the other end is connected to the extension head to drive the pressure plate to reciprocate vertically.

8. The closed-loop force-controlled dimension measuring device according to claim 7, characterized in that: The second vertical movement mechanism further includes a second reading device, which is connected to the second sliding component and is used to measure the displacement of the protruding head; Alternatively, the second vertical moving mechanism may further include a grating displacement sensor, wherein the reading head of the grating displacement sensor is fixed to the second fixing member, and the grating ruler of the grating displacement sensor is fixed to the second sliding member; And / or, the second sliding component is a cross roller guide.

9. The closed-loop force-controlled dimension measuring device according to claim 7, characterized in that: The drive device includes a control board and a linear motor electrically connected to the control board. The control board and the stator of the linear motor are respectively connected to the fixed frame, and the mover of the linear motor is connected to the protruding head. And / or, the drive device includes a control board and a linear motor electrically connected to the control board, the control board and the stator of the linear motor are respectively connected to the fixed frame, and the mover of the linear motor is connected to the protruding head.

10. A method for measuring dimensions, characterized in that, A closed-loop force-controlled dimension measuring device according to any one of claims 1 to 9 includes the following steps: Place the calibration weight on the platform, calibrate the force sensor, and then remove the calibration weight. The size is T 0 The standard block is placed on the platform, and the lower surface of the pressure plate is pressed against the upper surface of the standard block using the first vertical moving mechanism; Read the pressure value of the force sensor P 1 Obtain the displacement of the pressure plate. A 1 and the deformation of the force sensor B 1 Remove the standard block; The workpiece to be tested is placed on the platform, and the first vertical moving mechanism is used to apply the pressure value to the lower surface of the pressure plate. P 1 It is attached to the upper surface of the workpiece to be tested; Obtain the displacement of the pressure plate A 2 and the deformation of the force sensor B 2 ; Calculate the dimensions of the workpiece to be measured. T=T 0 +( A 1 - A 2 ) + ( B 1 - B 2 ).

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