Clamping force measurable presser plate system for machine tools and method for measuring clamping force using the same

Abstract

The present application relates to the field of fixture design for machine tools, in particular to a machine tool clamping force measuring clamp plate system and a method for measuring clamping force using the same. The system is composed of a clamp plate, a tail support device and a pressure regulating device. The clamp plate is a whole plate body and has an axisymmetric structure. A boss is arranged in the central region of the clamp plate and serves as a force beam. A through hole is arranged in the central region of the force beam. The clamp plate body is divided into a force transmission beam, a sensing beam and a contact beam region. The length direction edge region is the force transmission beam, the width direction edge region is the contact beam, and the remaining middle region is the sensing beam. The sensing beam is separated from the edge force transmission beam through the long holes on its two sides. Four strain gauges are fixed on the surface of the sensing beam on one side of the through hole. The four strain gauges are connected to form a Wheatstone bridge circuit. The present application solves the defects and limitations of traditional clamp plates that cannot control clamping force, preventing processing errors and surface defects caused by improper clamping force application.

Description

Technical Field

[0001] This invention relates to the field of machine tool fixture design, and particularly to a pressure plate system for measuring clamping force for machine tools and a method for measuring clamping force using the same. Background Technology

[0002] In recent years, more and more high-performance and high-requirement workpieces have emerged in fields such as aerospace, defense technology, and nuclear power equipment. For example, the surface accuracy, surface integrity, and consistency of aero-engine blades have a significant impact on fatigue life and aerodynamic performance under service conditions. The root mean square roughness (EMS) requirement of the primary mirror of the James Webb Telescope is 4nm to 20nm, which has a significant impact on the telescope's observation results. The permanent magnets of permanent magnet motors in nuclear submarines require extremely high roundness; otherwise, the vibration of the rotor will be difficult to meet the requirements, and may even lead to dynamic imbalance. All of these place more stringent requirements on the surface quality and geometric accuracy of mechanical manufacturing.

[0003] Fixtures are crucial for ensuring the workpiece occupies the correct position on the machine tool plane during machining, and are a vital factor in process planning. They directly impact the final geometric accuracy and surface quality of the workpiece. During manufacturing, fixtures should apply appropriate clamping force to the workpiece. However, due to inherent structural defects, traditional clamping plates cannot measure the clamping force applied to the workpiece during clamping. Therefore, the clamping force control of traditional clamping plates is highly dependent on the operator's experience, making reliable measurement and control impossible. A common problem with traditional clamping plates is the mismatch between the actual clamping force and the required clamping force on the workpiece. Excessive clamping force can lead to pits or micro-cracks on the clamped surface; insufficient clamping force can cause displacement or chatter on the workpiece under cutting loads, resulting in increased surface roughness. Both of these situations severely affect the workpiece's geometric accuracy and surface quality, significantly reducing its service life under harsh operating conditions and consequently impacting the overall lifespan of the equipment. Therefore, there is an urgent need to design a new type of pressure plate that can monitor the clamping force in real time throughout the manufacturing process, so as to achieve reliable clamping force measurement and control and provide an original reference for subsequent initial clamping force setting. Summary of the Invention

[0004] The purpose of this invention is to provide a novel clamping plate system for machine tools that can measure clamping force, thereby overcoming the shortcomings and limitations of traditional clamping plates that cannot control clamping force, and preventing machining errors and surface defects caused by improper application of clamping force. To achieve the above-mentioned objective, the technical solution of this invention is as follows:

[0005] A clamping force measuring pressure plate system for machine tools, the system comprising a pressure plate, a tail support device, and a pressure regulating device, wherein the pressure plate is a single plate with an axisymmetric structure; a boss is provided in the central area of ​​the pressure plate, which serves as a force-bearing beam, and a through hole is provided in the center of the force-bearing beam; the pressure plate body is divided into a force-transmitting beam, a sensing beam, and a contact beam area, wherein the edge area in the length direction is the force-transmitting beam, the edge area in the width direction is the contact beam, and the remaining middle area is the sensing beam, the sensing beam being separated from the force-transmitting beam located at the edge by partition grooves on both sides; four strain gauges are attached to the surface of the sensing beam on one side of the through hole: strain gauge I, strain gauge II, strain gauge III, and strain gauge IV, the four strain gauges being interconnected to form a Wheatstone bridge circuit.

[0006] In the above technical solution, the pressure plate system for measuring clamping force of the machine tool consists of three main mechanisms, namely, a pressure plate, a tail support device, and a pressure regulating device.

[0007] In the above technical solution, the pressure plate is an integral plate with an axisymmetric structure and a boss in the center. The boss and the plate body are an integral structure. There is a through hole in the center of the boss (which is also the center of the plate body) so that the T-slot can be tightened by passing a bolt through the through hole.

[0008] Preferably, the width of the load-bearing beam is the same as the width of the pressure plate body.

[0009] In the above technical solution, the pressure plate and the load-bearing beam are an integrated structure.

[0010] In the above technical solution, the pressure plate is divided into force transmission beam, sensing beam, and contact beam areas. The length-direction edge area is the force transmission beam area; the width-direction edge area is the contact beam area. The contact beam areas located at both ends of the pressure plate have their lower surfaces (tail end) in contact with the upper surface of the support head of the tail support device, and their lower surfaces (head end) in contact with the workpiece clamping surface. Besides the contact beam and force transmission beam areas, the remaining middle area of ​​the pressure plate is the sensing beam area. Four strain gauges are attached to the surface of the sensing beam near the head end of the contact beam, and these strain gauges are interconnected to form a Wheatstone bridge circuit. This Wheatstone bridge circuit constitutes a strain gauge circuit.

[0011] In the above technical solution, two partition grooves are symmetrically arranged on both sides of the pressure plate body. The sensing beam is separated from the force transmission beam located at the edge by the partition grooves on both sides. The partition grooves are vertically continuous.

[0012] In the above technical solution, the system further includes a data acquisition device, which can measure the clamping force through a strain circuit and display the clamping force data through the data acquisition device.

[0013] In the above technical solution, the pressure regulating device is used to control the pressure applied to the load-bearing beam.

[0014] Preferably, the pressure regulating device includes a T-slot tightening bolt, a tightening nut, and a bottom slide for fixing to the plane of the machine tool operating table. The upper surface of the load-bearing beam is in contact with the lower surface of the tightening nut. The T-slot tightening bolt passes through the tightening nut and the through hole and engages with the interior of the bottom slide.

[0015] In the above technical solution, the tail support device is used to provide support force for the end of the pressure plate away from the strain gauge.

[0016] Preferably, the tail support device includes a support head, which is threadedly connected to the upper part of the double-ended stud, and the adjusting nut is threadedly engaged with the lower part of the double-ended stud; a nut sleeve is engaged with the adjusting nut and fitted over the adjusting nut; the thrust bearing is fixed inside the tail support base, and its upper surface is in contact with the adjusting nut and the nut sleeve.

[0017] Another object of the present invention is to provide a method for testing the clamping force of a workpiece using the above-described pressure plate system for measuring clamping force in machine tools.

[0018] A method for testing workpiece clamping force includes the following steps:

[0019] Fix the workpiece to be tested; measure the height of the clamping surface; adjust the height of the tail support head and fix the tail support; install the bottom slide; install the pressure plate; rotate and tighten the nut to apply clamping force to the workpiece; measure the clamping force through the strain circuit and display the clamping force data through the data acquisition device.

[0020] The beneficial effects of this invention are as follows: Compared with the prior art, this invention uses a strain gauge bridge circuit to measure the clamping force when the pressure plate clamps the workpiece, and displays the result in numerical form through a data acquisition device. This allows for a direct observation of the magnitude of the clamping force applied by the pressure plate to the workpiece, thereby enabling manual control of the clamping force applied by the pressure plate to the workpiece. This avoids insufficient clamping force causing the workpiece to move or vibrate during processing, affecting processing accuracy. It also avoids excessive clamping force causing pits or micro-cracks on the clamped surface of the workpiece, increasing the scrap rate. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a pressure plate system for machine tools with measurable clamping force according to the present invention;

[0022] Figure 2 This is a schematic diagram of the pressure plate structure in a pressure plate system for measuring clamping force in a machine tool according to the present invention;

[0023] Figure 3This is a schematic diagram of the tail support device in a pressure plate system for measuring clamping force in a machine tool according to the present invention.

[0024] Figure 4 This is a schematic diagram showing the relative position of the pressure plate and the workpiece being clamped in a pressure plate system for measuring clamping force in a machine tool according to the present invention.

[0025] The attached figures are labeled as follows:

[0026] 1-Tighten bolts in T-slot; 2-Tighten nuts; 3-Pressure plate; 4-Bottom slide; 5-Support head; 6-Double-ended stud; 7-Phillips head screw; 8-Cover plate; 9-Nut sleeve; 10-Tail support base; 11-Adjusting nut; 12-Thrust bearing; 13-Strain gauge I; 14-Strain gauge II; 15-Strain gauge III; 16-Strain gauge IV; 17-Sensing beam; 18-Force beam; 19-Contact beam; 20-Force transmission beam; 21-Clamped workpiece; 22-Separation groove. Detailed Implementation

[0027] To better understand the technical content and beneficial effects of the present invention, the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and should not be construed as limiting the scope of the present invention.

[0028] This invention provides a novel clamping plate system for machine tools that can measure clamping force. The main function of the system is to provide clamping force to the workpiece and measure the magnitude of the clamping force in real time.

[0029] The system mainly includes a T-slot tightening bolt 1, a tightening nut 2, a pressure plate 3, a strain circuit composed of strain gauges I13, II14, III15, and IV16, a bottom slide 4, and a tail support device composed of a support head 5, a double-ended stud 6, a Phillips head screw 7, a cover plate 8, a nut sleeve 9, a tail support base 10, an adjusting nut 11, and a thrust bearing 12.

[0030] The pressure plate includes a load-bearing beam 18, a force-transmitting beam 20, a sensing beam 17, and a contact beam 19. Two axially symmetrical partition grooves are arranged on both sides of the pressure plate body. The sensing beam is separated from the force-transmitting beam located at the edge by the partition grooves on both sides. Four strain gauges are attached to the surface of the sensing beam 17 of the pressure plate. Strain gauges I13, II14, III15, and IV16 are interconnected to form a Wheatstone bridge circuit. The load-bearing beam 18 has a through hole in the middle, through which a T-slot can be fitted with a tightening bolt 1 and a tightening nut 2. The upper surface of the load-bearing beam 18 should contact the lower surface of the tightening nut 2. One end of the contact beam 19 at both ends of the pressure plate should contact the workpiece clamping surface, and the other end should contact the upper surface of the tail support head 5. The bottom slide groove 4 can be fixed to the machine tool operating table plane with bolts, and its interior can cooperate with the T-slot using the tightening bolt 1. The support head 5 is threadedly connected to the double-ended stud 6, and the adjusting nut 11 is threadedly engaged with the double-ended stud 6. The nut sleeve 9 can be engaged with the adjusting nut 11. The thrust bearing 12 is installed inside the tail support base 10, and its upper surface is in contact with the adjusting nut 11 and the nut sleeve 9.

[0031] This invention provides a method for testing workpiece clamping force, which uses the aforementioned system and includes the following steps: fixing the workpiece to be clamped; adjusting the height of the upper surface of the tail support head according to the thickness of the workpiece to be tested, so that its upper surface is flush with the workpiece clamping surface; fixing the tail support to the machine tool operating table plane with bolts; installing the bottom slide groove according to the position of the workpiece to be clamped and the position of the tail support, so that the bottom slide groove is approximately below the through hole of the pressure plate force beam; installing the T-slot in the bottom slide groove with tightening bolts; passing the pressure plate through the T-slot with tightening bolts and adjusting the position of the pressure plate and the T-slot with tightening bolts so that the contact beams at both ends of the pressure plate are in contact with the workpiece surface and the support head surface, respectively; adjusting the tightening nut to apply downward pressure to the pressure plate, the pressure plate sensing beam undergoes S-shaped deformation, and the voltage at both ends of the strain bridge composed of strain gauges attached to the surface of the pressure plate sensing beam changes. The clamping force data can be acquired by the acquisition device and displayed. Example

[0032] This invention provides a pressure plate system for measuring clamping force in machine tools, comprising a T-slot tightening bolt 1, a tightening nut 2, a pressure plate 3, a bottom slide 4, a support device consisting of a support head 5, a double-ended stud 6, a Phillips head screw 7, a cover plate 8, a nut sleeve 9, a tail support base 10, an adjusting nut 11, and a thrust bearing 12, and a strain circuit consisting of strain gauges I13, II14, III15, and IV16 attached to the upper surface of the pressure plate sensing beam. The bottom slide 4 and the tail support device are mounted on the surface of the machine tool operating table. The T-slot tightening bolt 1 cooperates with the bottom slide 4, and the T-slot tightening bolt 1 can slide within the bottom slide 4 to adjust the horizontal position of the pressure plate to adapt to different workpiece installation positions. Rotating the tightening nut 2 applies downward pressure to the pressure plate force beam 18. This downward pressure is transmitted to the force transmission beam 20 and the contact beam 19, causing the contact beam 19 to have a vertical downward movement tendency. Since the workpiece clamping surface is in close contact with the lower surface of the contact beam 19, the contact beam 19 can form a clamping force on the workpiece. The strain circuit composed of strain gauges I13, II14, III15, and IV16 attached to the upper surface of the pressure plate sensing beam can convert the micro-strain of the pressure plate sensing beam 17 into a change in voltage across a bridge circuit after the pressure plate 3 is subjected to force. The magnitude of the pressure plate clamping force can be obtained by acquiring this voltage through a data acquisition device. The support head 5 and the double-ended stud 6 are connected together by threads, and the two can move together in the vertical direction. The adjusting nut 11 in the tail support can adjust the height of the support head 5. Rotating the adjusting nut 11 converts the rotational movement of the adjusting nut 11 into the vertical movement of the double-ended stud 6, thereby driving the support head 5 to move. This ensures that the support head is in close contact with the lower surface of the pressure plate contact beam 19, providing upward support force to the pressure plate 3 and maintaining the pressure plate's force balance. The thrust bearing 12 provides upward support force to the adjusting nut 11 and allows it to rotate around its own axis. The data acquisition device is used for data acquisition, processing, and display. In this embodiment, the acquisition device is a microcontroller, which can communicate wirelessly with a computer to record and save data.

[0033] The specific steps for clamping a part using the novel clamping plate system with measurable clamping force on the aforementioned machine tool are as follows:

[0034] The first step is to mount the workpiece onto the fixture according to the workpiece positioning reference;

[0035] The second step is to align the workpiece.

[0036] The third step is to clamp the workpiece after alignment.

[0037] Fourth step: Adjust the height of the upper surface of the tail support head 5 according to the height of the workpiece clamping surface until it is level with the clamping surface, and fix the tail support device with bolts.

[0038] Fifth step: Install the bottom slide groove 4 according to the position of the workpiece and the position of the tail support device, so that its position is approximately below the through hole of the pressure plate bearing beam 18;

[0039] Step 6: Install the pressure plate 3 according to the position of the workpiece and the position of the support head 5, so that the pressure plate can reliably contact the contact beam 19 on both sides and the workpiece surface and the upper surface of the support head 5 respectively.

[0040] Step 7: Tighten nut 2 by rotating it to apply clamping force to the workpiece. The clamping force data will be displayed by the acquisition device.

[0041] Matters not covered in this invention are common knowledge. Furthermore, it should be understood that the above-described embodiments are only used to explain the invention in detail, but the invention is not limited to the detailed methods described above. For those skilled in the art, any improvements to the invention, equivalent substitutions of raw materials for the product, selection of specific methods, etc., within the spirit and principles of the invention, should be covered within the scope of protection and disclosure of this invention.

Claims

1. A clamping plate system for machine tools that can measure clamping force, characterized in that, The system consists of a pressure plate (3), a tail support device, and a pressure regulating device. The pressure plate (3) is an integral plate with an axisymmetric structure. A boss is provided in the central area of ​​the pressure plate (3), which is a load-bearing beam (18). A through hole is provided in the center of the load-bearing beam (18). The body of the pressure plate (3) is divided into a force transmission beam (20), a sensing beam (17), and a contact beam (19). The edge area in the length direction is the force transmission beam (20), the edge area in the width direction is the contact beam (19), and the remaining middle area is the sensing beam (17). The sensing beam (17) communicates with the position through the partition grooves (22) on both sides. Separated by the force transmission beam (20) at the edge, the width of the force beam (18) is the same as the width of the pressure plate (3) body; rotating and tightening the nut (2) can apply downward pressure to the pressure plate force beam (18), which will be transmitted to the force transmission beam (20) and the contact beam (19), and make the contact beam (19) have a vertical downward movement tendency; four strain gauges are attached to the surface of the sensing beam (17) on the through hole side: strain gauge I (13), strain gauge II (14), strain gauge III (15), strain gauge IV (16), and the four strain gauges are connected to each other to form a Wheatstone bridge circuit.

2. The system according to claim 1, characterized in that, The pressure regulating device is used to control the pressure applied to the load-bearing beam (18).

3. The system according to claim 1 or 2, characterized in that, The pressure regulating device includes a T-slot tightening bolt (1), a tightening nut (2), and a bottom slide (4) for fixing to the plane of the machine tool operating table. The upper surface of the load-bearing beam (18) is in contact with the lower surface of the tightening nut (2). The T-slot tightening bolt (1) passes through the tightening nut (2) and the through hole is engaged with the inside of the bottom slide (4).

4. The system according to claim 1, characterized in that, The tail support device is used to provide support force to the end of the pressure plate away from the strain gauge.

5. The system according to claim 1 or 4, characterized in that, The tail support device includes a support head (5), which is connected to the upper part of the double-ended stud (6) by a thread, and the adjusting nut (11) is connected to the lower part of the double-ended stud (6) by a threaded pair; the nut sleeve (9) is fitted to the adjusting nut (11) and is fitted outside the adjusting nut (11); the thrust bearing (12) is fixed inside the tail support base (10), and its upper surface is in contact with the adjusting nut (11) and the nut sleeve (9).

6. A method for testing the clamping force of a workpiece, characterized in that, Includes the following steps: Fix the workpiece to be tested; measure the height of the clamping surface; adjust the height of the tail support head (5) and fix the tail support device; install the bottom slide (4); install the pressure plate (3); rotate and tighten the nut (2) to apply clamping force to the workpiece; measure the clamping force through the strain circuit and display the clamping force data through the data acquisition device. The method for testing the workpiece clamping force is performed in a pressure plate system for measuring clamping force on a machine tool. The system consists of a pressure plate (3), a tail support device, and a pressure regulating device. The pressure plate (3) is an integral plate with an axisymmetric structure. A boss is provided in the central area of ​​the pressure plate (3), which is a load-bearing beam (18). A through hole is provided in the center of the load-bearing beam (18). The body of the pressure plate (3) is divided into a force transmission beam (20), a sensing beam (17), and a contact beam (19). The edge area in the length direction is the force transmission beam (20), the edge area in the width direction is the contact beam (19), and the remaining middle area is the sensing beam (17). The sensing beam (17) communicates with the position through the partition grooves (22) on both sides. Separated by the force transmission beam (20) at the edge, the width of the force-bearing beam (18) is the same as the width of the pressure plate (3) body; rotating and tightening the nut (2) can apply downward pressure to the pressure plate force-bearing beam (18), which will be transmitted to the force transmission beam (20) and the contact beam (19), and make the contact beam (19) have a vertical downward movement tendency; four strain gauges are attached to the surface of the sensing beam (17) on the through hole side: strain gauge I (13), strain gauge II (14), strain gauge III (15), strain gauge IV (16), and the four strain gauges are connected to each other to form a Wheatstone bridge circuit; The pressure regulating device includes a T-slot tightening bolt (1), a tightening nut (2), and a bottom slide (4) for fixing to the plane of the machine tool operating table. The upper surface of the load-bearing beam (18) is in contact with the lower surface of the tightening nut (2). The T-slot tightening bolt (1) passes through the tightening nut (2) and the through hole is engaged with the inside of the bottom slide (4). The tail support device includes a support head (5), which is connected to the upper part of the double-ended stud (6) by a thread, and the adjusting nut (11) is connected to the lower part of the double-ended stud (6) by a threaded pair; the nut sleeve (9) is fitted to the adjusting nut (11) and is fitted outside the adjusting nut (11); the thrust bearing (12) is fixed inside the tail support base (10), and its upper surface is in contact with the adjusting nut (11) and the nut sleeve (9).

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