A precise constant force clamping system based on spatial constraints

Abstract

The application discloses a kind of precision constant force clamping systems based on space constraint, it is related to micro electro mechanical actuator precision operation technical field, including overall frame and linear driver, the upper end of linear driver and the top of overall frame are fixedly connected, the lower end of linear driver is fixedly connected with connecting block, the lower end of connecting block is fixedly connected with input movable rod, input movable rod is provided with primary constant force mechanism, the lower of primary constant force mechanism is provided with secondary constant force mechanism, secondary constant force mechanism is arranged on base, the lower of base is provided with bottom plate.The application adopts the above structure of a kind of precision constant force clamping systems based on space constraint, solve the problem that plane structure is easy to occur out-of-plane deviation, increase constraint, and the better guiding property is changed, greatly reduce out-of-plane deviation, clamping force will be more stable, and the effect of clamping will be better.

Description

Technical Field

[0001] This invention relates to the field of precision operation technology of microelectromechanical actuators, and in particular to a precision constant force clamping system based on spatial constraints. Background Technology

[0002] In existing technologies, there are precision constant force clamping systems that employ zero-stiffness mechanisms, meaning that the output force remains constant as displacement increases. This avoids the increased cost and difficulty associated with force control and is easily miniaturized. However, existing clamps are all planar mechanisms, such as those described in the papers "FEA-based optimization and experimental verification of a typical flexure-based constant force module" and "Design of a new passive end-effector based on constant-force mechanism for robotic polishing," as well as patent CN206241884U. CN206241884U also uses a planar structure, which is prone to out-of-plane offset. Due to the lack of constraints, the guidance is not good, resulting in poor clamping performance. The inventors discovered that using a spatial structure can greatly reduce out-of-plane offset, resulting in more stable clamping force and better clamping performance. Furthermore, the secondary constant force mechanism of this precision constant force clamping system is detachable and can be replaced with a fixed clamping arm or other constant force mechanisms to obtain different constant forces, thus broadening the application scenarios. Summary of the Invention

[0003] The purpose of this invention is to provide a precision constant force clamping system based on spatial constraints, which solves the problem of out-of-plane offset that easily occurs when achieving constant force output in the prior art. This invention can reduce out-of-plane offset during clamping by increasing spatial constraints, thereby improving clamping stability. At the same time, the secondary constant force mechanism is detachable and can be optionally replaced with a fixed rod, which can achieve the beneficial effect of adjusting the magnitude of the output constant force.

[0004] To achieve the above objectives, the present invention provides a precision constant force clamping system based on spatial constraints, comprising an overall frame and a linear actuator. The upper end of the linear actuator is fixedly connected to the top of the overall frame, and the lower end of the linear actuator is fixedly connected to a connecting block. The lower end of the connecting block is fixedly connected to an input movable rod. A primary constant force mechanism is provided on the input movable rod, and a secondary constant force mechanism is provided below the primary constant force mechanism. The secondary constant force mechanism is mounted on a base, and a base plate is provided below the base.

[0005] Preferably, the primary constant force mechanism includes a primary positive stiffness mechanism and a primary negative stiffness mechanism disposed below the primary positive stiffness mechanism. Both the primary negative stiffness mechanism and the primary positive stiffness mechanism are provided in two sets, with the two sets of the primary positive stiffness mechanism and the two sets of the primary negative stiffness mechanism being disposed at 90° to each other.

[0006] Preferably, both sets of the first-level positive stiffness mechanism include two sets of leaf spring assemblies symmetrically arranged on both sides of the input movable rod. Both sets of leaf spring assemblies include a first leaf spring, one end of which is connected to the input movable rod, and the other end of which is connected to one end of a second leaf spring via a first mass block. The other end of the second leaf spring is connected to one end of a third leaf spring via a second mass block, and the other end of the third leaf spring is connected to the upper end of the rigid body.

[0007] Preferably, both sets of the first-level negative stiffness mechanism include inclined leaf springs symmetrically arranged on both sides of the input movable rod, one end of the inclined leaf spring is fixedly connected to the lower end of the input movable rod, and the other end of the inclined leaf spring is fixedly connected to the lower end of the rigid body.

[0008] Preferably, the lower end of the input movable rod is connected to a first clamping arm, a second clamping arm is disposed below the first clamping arm, and the second clamping arm is disposed at the top of the secondary constant force mechanism.

[0009] Preferably, the secondary constant force mechanism includes a secondary positive stiffness mechanism and a secondary negative stiffness mechanism disposed inside the secondary positive stiffness mechanism. Both the secondary negative stiffness mechanism and the secondary positive stiffness mechanism are provided in two sets, with the two sets of the secondary positive stiffness mechanism arranged at 90° to each other, and the two sets of the secondary negative stiffness mechanism also arranged at 90° to each other.

[0010] Preferably, both sets of the secondary positive stiffness mechanisms include a fourth leaf spring and a fifth leaf spring symmetrically arranged along the center line of the overall frame, and the fifth leaf spring and the fourth leaf spring are fixedly connected by a third mass block.

[0011] Preferably, both sets of the secondary negative stiffness mechanisms include a sixth leaf spring and a seventh leaf spring symmetrically arranged along the center line of the overall frame. The seventh leaf spring and the sixth leaf spring are fixedly connected by a fourth mass block, and a straight beam is provided between the two symmetrically arranged fourth mass blocks.

[0012] Preferably, a grating ruler fixing frame is fixedly provided on the side end of the connecting block, the grating ruler fixing frame and the grating ruler are fixedly connected, a grating is provided on one side of the grating ruler, the grating and the grating fixing frame are fixedly connected, and the grating fixing frame is fixedly connected to the overall frame.

[0013] Preferably, the top of the overall frame has two fixing holes 1, and the base has multiple fixing holes 2.

[0014] Therefore, the precision constant force clamping system based on spatial constraints using the above structure of the present invention has the following beneficial effects:

[0015] (1) The spatially constrained precision constant force clamping system of the present invention solves the problem of out-of-plane displacement of planar structures by using space, increases constraints, improves guidance, greatly reduces out-of-plane displacement, makes the clamping force more stable, and makes the clamping effect better.

[0016] (2) The spatially constrained precision constant force clamping system of the present invention uses a combination of positive stiffness mechanism and negative stiffness mechanism to output constant force, replacing the costly and complex control algorithm, saving manpower, and avoiding damage caused by sudden increase in force during clamping.

[0017] (3) The spatially constrained precision constant force clamping system of the present invention adopts a combination of two constant force mechanisms, which can be used for a wider range of constant forces. The secondary constant force mechanism is detachable and can be replaced with a fixed rod. At this time, the magnitude of the constant force changes, which can achieve the beneficial effect of adjusting the magnitude of the output constant force.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an embodiment of a precision constant force clamping system based on spatial constraints according to the present invention;

[0020] Figure 2 This is a cross-sectional view of a precision constant force clamping system based on spatial constraints according to the present invention.

[0021] Figure 3 This is a front view of the primary constant force mechanism of a precision constant force clamping system based on spatial constraints according to the present invention.

[0022] Figure 4 This is a schematic diagram of the primary constant force mechanism of a precision constant force clamping system based on spatial constraints according to the present invention.

[0023] Figure 5 This is a front view of the two-stage constant force mechanism of a precision constant force clamping system based on spatial constraints according to the present invention.

[0024] Figure 6 This is a schematic diagram of a two-stage constant force mechanism of a precision constant force clamping system based on spatial constraints according to the present invention;

[0025] Figure 7This is a force-displacement relationship curve of the constant force mechanism of a precision constant force clamping system based on spatial constraints according to the present invention.

[0026] Figure 8 This is a schematic diagram of the constant force simulation results of a spatial constant force precision clamping system based on spatial constraints, according to the present invention.

[0027] Figure 9 This is a schematic diagram of the constant force simulation results of a planar constant force precision clamping system based on spatial constraints, according to the present invention.

[0028] Figure 10 This is a diagram showing the offset of the spatial and planar constant force precision clamping system based on spatial constraints according to the present invention on the z-axis.

[0029] Reference numerals: 1. Overall frame; 2. Linear actuator; 3. Connecting block; 4. Input movable rod; 5. First-stage constant force mechanism; 6. Second-stage constant force mechanism; 7. Base; 8. Base plate; 9. First leaf spring; 10. First mass block; 11. Second leaf spring; 12. Second mass block; 13. Third leaf spring; 14. Rigid body; 15. Inclined leaf spring; 16. First clamping arm; 17. Second clamping arm; 18. Fourth leaf spring; 19. Fifth leaf spring; 20. Third mass block; 21. Sixth leaf spring; 22. Seventh leaf spring; 23. Fourth mass block; 24. Straight beam; 25. Grating ruler fixing bracket; 26. Grating ruler; 27. Grating; 28. Grating fixing bracket; 29. ​​Fixing hole one; 30. Fixing hole two. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0032] Example

[0033] Please see Figure 1-10This invention provides a precision constant force clamping system based on spatial constraints, including an integral frame 1 and a linear actuator 2. The upper end of the linear actuator 2 is fixedly connected to the top of the integral frame 1. The top of the integral frame 1 has two fixing holes 29. The linear actuator 2 is a voice coil motor, which is divided into a stator and a mover. The upper end of the stator has two threaded holes, which are fixed to the two fixing holes 29 by screws. The lower end of the mover has two threaded holes, which are fixed to the corresponding through holes of the connecting block by screws.

[0034] A connecting block 3 is fixedly connected to the lower end of the linear actuator 2, and the connecting block 3 transmits driving force. An input movable rod 4 is fixedly connected to the lower end of the connecting block 3. A primary constant force mechanism 5 is connected to the input movable rod 4. A secondary constant force mechanism 6 is located below the primary constant force mechanism 5. The secondary constant force mechanism 6 is fixedly mounted on a base 7 by multiple bolts. The base 7 has multiple fixing holes 30 and is fixedly connected to the overall frame 1 by multiple screws. The secondary constant force mechanism 6 can be detached and replaced with a fixed base or other constant force mechanisms, suitable for more scenarios involving clamping different objects. A base plate 8 is located below the base 7.

[0035] The primary constant force mechanism 5 includes a primary positive stiffness mechanism and a primary negative stiffness mechanism positioned below it. The primary positive and negative stiffness mechanisms operate in parallel to provide constant force. Two sets of both the primary negative and positive stiffness mechanisms are provided, with the two sets of primary positive stiffness mechanisms positioned at a 90° angle to each other, and the two sets of primary negative stiffness mechanisms also positioned at a 90° angle to each other. The primary positive and negative stiffness mechanisms work together to form a zero-stiffness mechanism, providing constant force as displacement increases.

[0036] Both sets of primary stiffness mechanisms include two sets of leaf spring assemblies symmetrically arranged on both sides of the input movable rod 4. Both sets of leaf spring assemblies include a first leaf spring 9. One end of the first leaf spring 9 is connected to the input movable rod 4. The other end of the first leaf spring 9 is connected to one end of the second leaf spring 11 through the first mass block 10. The other end of the second leaf spring 11 is connected to one end of the third leaf spring 13 through the second mass block 12. The other end of the third leaf spring 13 is connected to the upper end of the rigid body 14. The rigid body 14 is fixedly connected to the overall frame 1 to ensure that the leaf springs will deform during movement without breaking.

[0037] Both sets of primary negative stiffness mechanisms include inclined leaf springs 15 symmetrically arranged on both sides of the input movable rod 4. One end of the inclined leaf spring 15 is fixedly connected to the lower end of the input movable rod 4, and the other end of the inclined leaf spring 15 is fixedly connected to the lower end of the rigid body 14. The input movable rod 4 drives the inclined leaf spring 15 to bend towards the clamp.

[0038] The lower end of the input movable rod 4 is connected to a first clamping arm 16, and a second clamping arm 17 is located below the first clamping arm 16. The second clamping arm 17 is located on top of the secondary constant force mechanism 6. Under the action of the linear actuator 2, the primary constant force mechanism 5 moves downward, which drives the first clamping arm 16 to move downward toward the second clamping arm 17 to achieve clamping. At this time, the secondary constant force mechanism 6 also moves downward.

[0039] The secondary constant force mechanism 6 includes a secondary positive stiffness mechanism and a secondary negative stiffness mechanism disposed within the secondary positive stiffness mechanism. Both the secondary positive and secondary negative stiffness mechanisms are rhomboid structures, and are connected in parallel to provide constant force. There are two sets of both the secondary negative and secondary positive stiffness mechanisms, with the two sets of positive and negative stiffness mechanisms positioned at 90° to each other. The two sets of positive and negative stiffness mechanisms together form a zero-stiffness mechanism, used to provide constant force.

[0040] Both sets of secondary stiffness mechanisms include a fourth leaf spring 18 and a fifth leaf spring 19 symmetrically arranged along the centerline of the overall frame 1. The fifth leaf spring 19 and the fourth leaf spring 18 are fixedly connected by a third mass block 20. The fourth leaf spring 18 and the fifth leaf spring 19 form a certain angle.

[0041] Both sets of secondary negative stiffness mechanisms include a sixth leaf spring 21 and a seventh leaf spring 22 symmetrically arranged along the centerline of the overall frame 1, with the sixth leaf spring 21 and the seventh leaf spring 22 forming a certain angle. The seventh leaf spring 22 and the sixth leaf spring 21 are fixedly connected by a fourth mass block 23, and a straight beam 24 is provided between the two symmetrically arranged fourth mass blocks 23. The added straight beam 24 restricts the movement of the sixth leaf spring 21 and the seventh leaf spring 22, and the buckling deformation of the straight beam 24 provides negative stiffness.

[0042] A grating ruler fixing bracket 25 is fixedly installed on the side end of the connecting block 3. The grating ruler fixing bracket 25 and the grating ruler 26 are fixedly connected by screws. A grating 27 is provided on one side of the grating ruler 26. The grating 27 and the grating fixing bracket 28 are fixedly connected by screws. The grating fixing bracket 28 is fixedly connected to the overall frame 1 by screws. The grating ruler 26 moves with the displacement given by the voice coil motor, while the grating ruler fixing bracket 25 remains stationary. At this time, the specific magnitude of the displacement given by the voice coil motor can be obtained through the host computer.

[0043] The specific working principle is as follows: The linear actuator 2 uses a voice coil motor. After being energized, the actuator outputs a vertically downward force, which pushes the input movable rod 4 to move downward, driving the first-stage constant force mechanism 5 to move vertically downward. During the movement, the first-stage positive stiffness mechanism generates positive stiffness, which is connected in parallel with the first-stage negative stiffness mechanism to generate a constant force. This force is transmitted downward through the first clamping arm 16. When it touches the object being clamped, the second clamping arm 17 also starts to work, and the second-stage constant force mechanism 6 also moves. At this time, the second-stage positive stiffness mechanism and the second-stage negative stiffness mechanism are connected in parallel to generate a constant force. As the displacement advances to a certain extent, both the first-stage constant force mechanism 5 and the second-stage constant force mechanism 6 output a constant force. Within this range, the clamping force on the object remains unchanged, and the spatial design makes the clamping more stable.

[0044] Figure 7 The diagram shows the relationship between force and displacement in a constant force mechanism, as well as the force-displacement relationship curve of a constant force mechanism composed of positive and negative stiffness mechanisms. In the curve of the positive stiffness mechanism, the force increases with the increase of displacement. In the curve of the negative stiffness mechanism, the force first increases with the displacement, then decreases, and then increases again. Buckling deformation occurs at points d1 and d2. Before reaching the constant force, the reaction force decreases with the increase of displacement. The combination of positive and negative stiffness mechanisms results in a zero stiffness mechanism, which is used to provide constant force.

[0045] Figure 8 This is a simulation diagram of a space constant force clamping system. Figure 9 The simulation diagram of the planar constant force clamping system shows that as the displacement supplied by the voice coil motor increases, both the positive stiffness mechanism and the negative stiffness mechanism deform. Among them, the negative stiffness mechanism undergoes buckling deformation, which is the key to providing negative stiffness.

[0046] Figure 10 A comparison of the z-axis offsets of the spatial constant force clamping system and the planar constant force clamping system shows that the z-axis offset of the spatial constant force clamping system is much smaller than that of the planar constant force clamping system. This indicates that the spatial constant force clamping system is more stable than the planar one.

[0047] Therefore, this invention employs a spatially constrained precision constant force clamping system with the aforementioned structure, solving the problem of out-of-plane offset that easily occurs in planar structures. It increases constraints, improves guidance, significantly reduces out-of-plane offset, and results in a more stable clamping force and better clamping effect. It utilizes a combination of positive and negative stiffness mechanisms to output constant force, replacing the costly and complex control algorithm, saving manpower and avoiding damage caused by sudden increases in force during clamping. The combination of two constant force mechanisms allows for a wider range of usable constant force, and the secondary constant force mechanism is detachable and can be replaced with a fixed rod. This allows for adjustments to the output constant force, achieving the beneficial effect of adjusting the magnitude of the constant force.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A precision constant force clamping system based on spatial constraints, characterized in that: The device includes an overall frame and a linear actuator. The upper end of the linear actuator is fixedly connected to the top of the overall frame, and the lower end of the linear actuator is fixedly connected to a connecting block. The lower end of the connecting block is fixedly connected to an input movable rod. A primary constant force mechanism is provided on the input movable rod, and a secondary constant force mechanism is provided below the primary constant force mechanism. The secondary constant force mechanism is provided on a base, and a base plate is provided below the base. The primary constant force mechanism includes a primary positive stiffness mechanism and a primary negative stiffness mechanism disposed below the primary positive stiffness mechanism. Both the primary negative stiffness mechanism and the primary positive stiffness mechanism are provided in two sets. The two sets of the primary positive stiffness mechanism are arranged at 90° to each other, and the two sets of the primary negative stiffness mechanism are also arranged at 90° to each other. The secondary constant force mechanism includes a secondary positive stiffness mechanism and a secondary negative stiffness mechanism disposed inside the secondary positive stiffness mechanism. Both the secondary negative stiffness mechanism and the secondary positive stiffness mechanism are provided in two sets. The two sets of the secondary positive stiffness mechanism are arranged at 90° to each other, and the two sets of the secondary negative stiffness mechanism are also arranged at 90° to each other. Both sets of the first-level positive stiffness mechanism include two sets of leaf spring assemblies symmetrically arranged on both sides of the input movable rod. Both sets of leaf spring assemblies include a first leaf spring. One end of the first leaf spring is connected to the input movable rod. The other end of the first leaf spring is connected to one end of the second leaf spring through a first mass block. The other end of the second leaf spring is connected to one end of the third leaf spring through a second mass block. The other end of the third leaf spring is connected to the upper end of the rigid body. Both sets of the first-level negative stiffness mechanism include inclined leaf springs symmetrically arranged on both sides of the input movable rod. One end of the inclined leaf spring is fixedly connected to the lower end of the input movable rod, and the other end of the inclined leaf spring is fixedly connected to the lower end of the rigid body. The lower end of the input movable rod is connected to a first clamping arm, and a second clamping arm is provided below the first clamping arm. The second clamping arm is located at the top of the secondary constant force mechanism. Both sets of the secondary positive stiffness mechanism include a fourth leaf spring and a fifth leaf spring symmetrically arranged along the center line of the overall frame, and the fifth leaf spring and the fourth leaf spring are fixedly connected by a third mass block; Both sets of the secondary negative stiffness mechanisms include a sixth leaf spring and a seventh leaf spring symmetrically arranged along the center line of the overall frame. The seventh leaf spring and the sixth leaf spring are fixedly connected by a fourth mass block, and a straight beam is provided between the two symmetrically arranged fourth mass blocks.

2. The precision constant force clamping system based on spatial constraints according to claim 1, characterized in that: A grating ruler fixing frame is fixedly installed on the side end of the connecting block. The grating ruler fixing frame and the grating ruler are fixedly connected. A grating is provided on one side of the grating ruler. The grating and the grating fixing frame are fixedly connected. The grating fixing frame is fixedly connected to the overall frame.

3. The precision constant force clamping system based on spatial constraints according to claim 2, characterized in that: The top of the overall frame has two fixing holes, and the base has multiple fixing holes.

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