A force standard and a method of measuring a force value using the same

Abstract

The present application relates to a kind of force standard and the force value measurement method using the force standard, force standard includes support, still include rotating cylinder sleeve and by respective corresponding first sealing ring and the upper and lower ends of rotating cylinder sleeve sealing cooperation first piston and second piston, first piston, second piston relative support rotation stop, first piston, second piston and rotating cylinder sleeve form piston cavity for filling liquid, force standard further include the pressure sensor connected with piston cavity, support or rotating cylinder sleeve is connected with the mounting arm of shaft line with rotating cylinder sleeve coaxial line arrangement on bearing, force measuring component is arranged between support and mounting arm, mounting arm is provided with the sleeve driving mechanism of transmission connection with rotating cylinder sleeve to drive rotating cylinder sleeve rotation.The present application solves the technical problem that the output force value of force output mechanism cannot be accurately measured due to the friction between cylinder body and piston not being considered in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of force value measurement, in particular to a force standard device and a force value measurement method using the same. BACKGROUND

[0002] Various force output mechanisms need to be calibrated for the accuracy of their force value output. The device capable of calibrating the force output mechanism is called a force standard device.

[0003] The existing hydraulic force standard device includes a cylinder body with a piston cavity, a piston is movably arranged in the piston cavity of the cylinder body, a sealing ring is arranged between the piston and the cylinder body, the piston cavity is filled with liquid, the force standard device further includes a pressure sensor connected with the piston cavity, and the pressure sensor is used for detecting the liquid pressure.

[0004] When calibrating the force output mechanism, the force output mechanism directly outputs pressure to the piston. For example, when calibrating a press, the ram of the press directly pushes the piston, the liquid is pressed, the pressure sensor detects the liquid pressure, and then the pressure of the liquid on the piston is converted according to the force area of the piston, which is considered as the pushing force of the ram on the piston. This calibration method can be used when the calibration accuracy requirement is not high. Once the calibration accuracy requirement is high, it is inaccurate because, according to the force analysis of the piston, the piston is not only subjected to the pushing force of the ram and the pressure of the liquid, but also subjected to the force of the sealing ring. The existing technology does not consider the force of the sealing ring on the piston, which affects the calibration accuracy requirement of the force output mechanism. SUMMARY

[0005] The present application aims to provide a force standard device to solve the technical problem that the friction between the cylinder body and the piston is not considered in the prior art, resulting in inaccurate measurement of the output force value of the force output mechanism. The present application also aims to provide a force value measurement method using the force standard device.

[0006] To solve the above technical problems, the technical scheme of a force standard device in the present application is as follows:

[0007] A force standard device includes a support, a rotating cylinder sleeve, a first piston and a second piston sealed and fitted with the rotating cylinder sleeve at the upper and lower ends thereof through respective first sealing rings, the first piston and the second piston being rotationally fixed relative to the support, the first piston, the second piston and the rotating cylinder sleeve enclosing a piston cavity for filling liquid, the force standard device further including a pressure sensor connected with the piston cavity, a mounting arm coaxially arranged with the rotating cylinder sleeve being connected to the support or the rotating cylinder sleeve through a bearing, a force measuring component being arranged between the support and the mounting arm, and a cylinder sleeve driving mechanism being arranged on the mounting arm and drivingly connected with the rotating cylinder sleeve to drive the rotating cylinder sleeve to rotate.

[0008] Further, the support has a support arm intersecting the mounting arm, and the force measuring component is connected between the mounting arm and the support arm.

[0009] Further, the force measuring component is a torque sensor.

[0010] Further, the first sealing ring is mounted on the outer periphery of the first piston and the second piston.

[0011] Further, the mounting arm is located on the upper side of the support arm, and the bearing includes an upper side bearing connected between the upper end of the mounting arm and the rotating sleeve and a lower side bearing connected between the lower end of the mounting arm and the support arm.

[0012] Further, the support includes a support base plate, the second piston is fixed on the support base plate, vertically arranged guide rods are arranged on the support base plate in a spaced manner, and the first piston is guided and moved in cooperation with the guide rods.

[0013] Further, a force sensor is arranged between the support arm and the support base plate.

[0014] Further, the second piston is provided with a second piston center hole, the first piston includes a first piston large diameter section in sealing cooperation with the rotating sleeve through the first sealing ring and a first piston small diameter section in sealing cooperation with the second piston center hole through the second sealing ring, the first piston large diameter section and the first piston small diameter section are provided with a first piston center hole, the cooperation gap between the first piston large diameter section and the rotating sleeve is the same as the cooperation gap between the first piston small diameter section and the second piston, and the materials of the first sealing ring and the second sealing ring are the same.

[0015] Further, the support includes a support base plate, the second piston is fixed on the support base plate, vertically arranged first guide rods and second guide rods are arranged on the support base plate in a spaced manner, the first piston is guided and moved in cooperation with the first guide rods and the second guide rods, the force measuring component is connected between the support base plate and the mounting arm, and the bearing includes an upper side bearing connected between the upper end of the mounting arm and the rotating sleeve and a lower side bearing connected between the lower end of the mounting arm and the support base plate.

[0016] The technical scheme of the force value measurement method in the utility model is:

[0017] The force value measurement method includes the following steps: the force output mechanism pushes the first piston, the sleeve driving mechanism drives the rotating sleeve to rotate at a constant speed,

[0018] When the first piston center hole is not provided on the first piston, the thrust force of the force output mechanism on the first piston is F=f1+PS, wherein P represents the reading of the pressure sensor, S represents the effective pressure area of the liquid on the first piston, and f1 represents the circumferential friction between the first sealing ring and the rotating cylinder sleeve, wherein f1=W / 2L, wherein W represents the torque measured by the force measuring component, and L represents the distance between the first sealing ring and the first piston center line.

[0019] When the first piston center hole is provided on the first piston, the thrust force of the force output mechanism on the first piston is F=f1+f2+PS, wherein P represents the reading of the pressure sensor, S represents the effective pressure area of the liquid on the first piston, f1 represents the circumferential friction between the first sealing ring and the rotating cylinder, and f2 represents the axial friction between the second sealing ring and the second piston, wherein f1=W / 2L, wherein W represents the torque measured by the force measuring component, and L represents the distance between the first sealing ring and the first piston center line, and f2=f1*L2 / L1, wherein L2 represents the circumference of the second sealing ring, and L1 represents the circumference of the first sealing ring.

[0020] The beneficial effects of the present application are as follows: in the present application, the rotating cylinder sleeve is driven by the cylinder sleeve driving mechanism to rotate at a uniform speed relative to the first piston. For the moving component, the circumferential friction between the first sealing ring and the rotating cylinder sleeve is equal in size to the axial friction between the first sealing ring and the rotating cylinder sleeve. By using this characteristic, the circumferential friction between the first sealing ring and the rotating cylinder sleeve is calculated by the measurement value of the force measuring component, and the axial friction between the first sealing ring and the rotating cylinder sleeve is obtained, so that the thrust force of the force output mechanism on the first piston is accurately calculated. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 is a structural schematic diagram of embodiment 1 of a force standard in the present application;

[0023] Figure 2 is a schematic diagram of the cooperation between the first piston and the rotating cylinder sleeve in embodiment 1;

[0024] Figure 3 is a structural schematic diagram of embodiment 2 of a force standard in the present application;

[0025] Explanation of reference signs: 1, top plate; 2, first piston; 3, rotating cylinder sleeve; 4, guide rod; 5, first sealing ring; 6, transmission chain belt; 7, transmission sprocket; 8, speed reducer motor; 9, mounting arm; 10, force measuring component; 11, support arm; 12, upper side bearing; 13, lower side bearing; 14, support bottom plate; 15, force sensor; 16, second piston; 17, pressure sensor; 18, water pump; 19, first piston center hole; 20, second piston center hole; 21, second sealing ring. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present application, the present application will be described in more detail below in conjunction with the drawings and specific embodiments. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described in the specification. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0027] It should be noted that, unless otherwise defined, all technical and scientific terms used in the specification have the same meaning as commonly understood by those skilled in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application.

[0028] Embodiment 1 of a force standardizer in the present application is shown in Figures 1-2 The embodiment includes a support, a rotating cylinder sleeve 3, and a first piston 2 and a second piston 16 sealed to the upper and lower ends of the rotating cylinder sleeve 3 through respective corresponding first sealing rings 5. In this embodiment, the first piston 2 is of solid structure, a first sealing ring 5 is arranged between the first piston 2 and the rotating cylinder sleeve 3, and a first sealing ring 5 is arranged between the second piston 16 and the rotating cylinder sleeve 3, each first sealing ring being mounted to the outer periphery of the first piston and the second piston. The first piston and the second piston are arranged in an up-down manner, the diameters of the first piston and the second piston are the same, and the fitting clearance between the first piston and the rotating cylinder sleeve is the same as the fitting clearance between the second piston and the rotating cylinder sleeve. The first piston, the second piston, and the rotating cylinder sleeve form a piston cavity for filling liquid.

[0029] The support includes a support bottom plate 14, the second piston 16 is fixed to the support bottom plate 14, vertically arranged guide rods 4 are arranged on the support bottom plate 14 at intervals, and the first piston is guided and moved in cooperation with each guide rod 4. That is, the second piston is fixed to the support bottom plate to be rotationally stopped relative to the support, and the first piston is guided and moved in cooperation with the first guide rod and the second guide rod to be rotationally stopped relative to the support. The upper end of the first piston has a top plate 1, and the top plate 1 is provided with a linear bearing guided and moved in cooperation with the corresponding guide rod.

[0030] The first piston, the second piston and the rotating cylinder sleeve enclose a piston cavity for filling liquid, the force standardizer further comprises a pressure sensor connected with the piston cavity, the pressure sensor is used for detecting the liquid pressure in the piston cavity.

[0031] The force standardizer further comprises a mounting arm 9 extending radially along the rotating cylinder sleeve, the support has a support arm 11 arranged intersecting with the mounting arm 9, the support arm 11 is fixed relative to the support bottom plate, the mounting arm 9 is connected with the rotating cylinder sleeve 3 and the support arm 11 through bearings, in the embodiment, the mounting arm 9 is located on the upper side of the support arm 11, the bearings comprise an upper side bearing 12 connected between the upper end of the mounting arm and the rotating cylinder sleeve and a lower side bearing 13 connected between the lower end of the mounting arm and the support arm.

[0032] The force measuring component 10 is arranged between the support arm 11 and the mounting arm 9, and the mounting arm is provided with a cylinder sleeve driving mechanism in transmission connection with the rotating cylinder sleeve to drive the rotating cylinder sleeve to rotate.

[0033] In the embodiment, the force measuring component 10 is a torque sensor (or a force sensor), the torque sensor is arranged horizontally, and the cylinder sleeve driving mechanism comprises a speed reducer motor 8, a transmission sprocket 7 is arranged at the power output end of the speed reducer motor 8, and the transmission sprocket 7 is in transmission connection with the rotating cylinder sleeve 3 through a transmission chain belt 6 to drive the rotating cylinder sleeve to rotate at a constant speed.

[0034] The support arm 11 and the support bottom plate 14 are provided with a vertically arranged force sensor 15.

[0035] The force standardizer further comprises a pressure sensor 17 for detecting the liquid pressure in the piston cavity, Figure 1 The medium 18 represents a water pump for pumping liquid into the piston cavity.

[0036] In use, when the force output mechanism is calibrated, taking a press as an example, the press head of the press applies a downward thrust F to the first piston, and because the liquid has an incompressible characteristic, no displacement occurs between the first piston and the rotating cylinder sleeve in the vertical direction, the cylinder sleeve driving mechanism drives the cylinder sleeve to rotate at a constant speed, the rotating cylinder sleeve rotates at a constant speed relative to the first sealing ring, and the cooperation gap between the first piston and the rotating cylinder sleeve determines the deformation amount of the first sealing ring when it is deformed by extrusion. For the rotating component, the circumferential friction and the axial friction between the rotating cylinder sleeve and the first sealing ring are equal to μN, μ represents the friction coefficient of the sealing ring, and N represents the normal pressure of the first sealing ring, and the normal pressure is only related to the cooperation gap between the rotating cylinder sleeve and the first sealing ring. Therefore, the circumferential friction and the axial friction between the rotating cylinder sleeve and the first sealing ring are the same in size, only different in direction.

[0037] It can also be analyzed as follows:

[0038] Let the axial friction force between the first sealing ring and the rotating cylinder sleeve be Fz; the circumferential friction force, i.e. the tangential friction force, between the first sealing ring and the rotating cylinder sleeve be Fq,

[0039] The friction pair formed by the first sealing ring and the rotating cylinder sleeve has no gap, so the contact area of the first sealing ring and the rotating cylinder sleeve is equal. For a certain amount of cylindrical surface contact area, we can decompose it into an infinite number of but equal number of infinitesimal two contact planes. For the friction pair formed by the nth infinitesimal contact plane, the material, material surface roughness, friction coefficient, and normal pressure size are isotropic. That is, the axial friction force Fzn is equal to the tangential friction force Fqn.

[0040] That is: Fzn=Fqn

[0041] Similarly: Fz1=Fq1; Fz2=Fq2;...

[0042] It is not difficult to deduce that: Fz1+Fz2+...+Fzn=Fq1+Fq2+...+Fqn

[0043] That is: Fz=Fq ——Equation One

[0044] Therefore, for a pair of cylindrical surface friction pairs, the axial friction force between the two components is the same as the circumferential friction force, i.e. the tangential friction force.

[0045] Using this phenomenon, we can detect the torque when the rotating cylinder sleeve rotates, convert it into the tangential friction force between the first piston and the rotating cylinder sleeve, replace the axial friction force with the equivalent tangential friction force, and use the axial friction force for axial force compensation.

[0046] That is, the force output mechanism has a pushing force F=f1+PS on the first piston, where P represents the reading of the pressure sensor, S represents the effective pressure area of the liquid on the first piston, and f1 represents the circumferential friction force between the first sealing ring and the rotating cylinder sleeve, where f1=W / 2L, where W represents the torque measured by the force measuring component, and L represents the distance between the first sealing ring and the center line of the first piston; in other embodiments of the present application, the force measuring component can also obtain W by measuring the force received by the mounting arm when the rotating cylinder sleeve rotates.

[0047] An embodiment 2 of a force standardizer is as follows: Figure 3As shown: the difference between Example 2 and Example 1 is that, in this example, the first piston 2 and the second piston 16 are both hollow structures, specifically, the second piston is provided with a second piston center hole 20, the first piston includes a first piston large diameter section in sealing cooperation with the rotating cylinder sleeve through a first sealing ring 5 and a first piston small diameter section in sealing cooperation with the second piston center hole through a second sealing ring 21, and the first piston large diameter section and the first piston small diameter section are provided with a first piston center hole 10. The cooperation gap between the first piston large diameter section and the rotating cylinder sleeve is the same as the cooperation gap between the first piston small diameter section and the second piston, and the materials of the first sealing ring and the second sealing ring are the same.

[0048] The support includes a support bottom plate 14, the second piston 16 is fixed on the support bottom plate 14, the support bottom plate 14 is provided with vertically arranged guide rods at intervals, the first piston is guided and moved in cooperation, the force measuring component 10 is connected between the support bottom plate 14 and the mounting arm 9, and the bearing includes an upper bearing 12 connected between the upper end of the mounting arm and the rotating cylinder sleeve and a lower bearing 13 connected between the lower end of the mounting arm and the support bottom plate.

[0049] In this example, the first piston adopts a hollow structure, so it can be applied to the calibration of force output mechanisms in some special fields, for example, when the tension of a cable is calibrated, the cable can pass through the first piston center hole.

[0050] While facilitating calibration, compared with Example 1, the force acting on the first piston in this example is increased by f2, f2 represents the axial friction between the second sealing ring and the second piston.

[0051] And f2 = f1 * L2 / L1, in the formula, L2 represents the circumference of the second sealing ring, L1 represents the circumference of the first sealing ring, and f1 is the same as f1 in Example 1.

[0052] This is because, when the sealing rings are squeezed to the same extent, the axial force acting on the sealing rings of the same material (the friction coefficient of the sealing rings is the same) is only related to the circumferential length of the sealing rings.

[0053] An embodiment 1 of a force value measurement method is as shown in Figures 1-2 As shown: the force value measurement method of Example 1 is the force value measurement method using the force standard device of Example 1, which includes the following steps: the force output mechanism pushes the first piston, the cylinder sleeve driving mechanism drives the rotating cylinder sleeve to rotate at a constant speed,

[0054] When the first piston center hole is not provided on the first piston, the pushing force of the force output mechanism on the first piston is F = f1 + PS, wherein P represents the reading of the pressure sensor, S represents the effective pressure area of the liquid on the first piston, and f1 represents the circumferential friction between the first sealing ring and the rotating cylinder sleeve, wherein f1 = W / 2L, wherein W represents the torque measured by the force measuring component, and L represents the distance between the first sealing ring and the first piston center line.

[0055] Embodiment 2 of the force value measuring method is shown in Figure 3 Embodiment 2 of the force value measuring method is shown in

[0056] The pushing force of the force output mechanism on the first piston is F = f1 + f2 + PS, wherein P represents the reading of the pressure sensor, S represents the effective pressure area of the liquid on the first piston, f1 represents the circumferential friction between the first sealing ring and the rotating cylinder, and f2 represents the axial friction between the second sealing ring and the second piston, wherein f1 = W / 2L, wherein W represents the torque measured by the force measuring component, L represents the distance between the first sealing ring and the first piston center line, and f2 = f1*L2 / L1, wherein L2 represents the circumference of the second sealing ring, and L1 represents the circumference of the first sealing ring.

[0057] In the above description of the present specification, unless otherwise explicitly specified and limited, the terms "fixed", "mounted", "connected" or "linked" and the like should be understood in a broad sense. For example, as to the term "connected", it can be fixed connection, detachable connection, or integral; it can be mechanical connection, electrical connection; it can be direct connection, indirect connection through intermediate medium, or internal connection of two elements or interaction relationship between two elements. Therefore, unless otherwise explicitly limited in the present specification, the above terms can be understood in the specific meaning in the present application by the person skilled in the art according to the specific circumstances.

[0058] According to the above description of the present specification, those skilled in the art can also understand that the terms used such as "upper", "lower", "front", "back", "left", "right", "length", "width", "thickness", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", "center", "longitudinal", "transverse", "clockwise" or "counterclockwise" and other terms indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings of the present specification, which are only for the purpose of facilitating the description of the present application and simplifying the description, and are not explicitly or implicitly indicating that the devices or elements involved must have the specific orientation, be constructed and operated in a specific orientation, therefore the above orientation or positional relationship terms cannot be understood or interpreted as a limitation on the technical solutions of the present application.

[0059] In addition, the terms "first" or "second" and the like used in the present specification are terms used to refer to numbers or ordinal numbers only for the purpose of description, and cannot be understood as explicitly or implicitly indicating relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first" or "second" can explicitly or implicitly include at least one of the features. In the description of the present specification, the meaning of "plurality" is at least two, such as two, three or more, etc., unless otherwise explicitly and specifically limited.

[0060] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A force standard, characterized in that: The device includes a support, a rotating cylinder liner, and a first piston and a second piston that are sealed to the upper and lower ends of the rotating cylinder liner via corresponding first sealing rings. The first piston and the second piston are anti-rotating relative to the support. The first piston, the second piston, and the rotating cylinder liner form a piston chamber for filling with liquid. The force standard also includes a pressure sensor connected to the piston chamber. A mounting arm with its axis coaxial with the rotating cylinder liner is connected to the support or the rotating cylinder liner via a bearing. A force measuring component is provided between the support and the mounting arm. A cylinder liner drive mechanism is provided on the mounting arm to drive the rotating cylinder liner to rotate. The support has a support arm that is arranged crosswise with the mounting arm. The force measuring component is connected between the mounting arm and the support arm. The mounting arm is located on the upper side of the support arm. The bearing includes an upper bearing connected between the upper end of the mounting arm and the rotating cylinder liner and a lower bearing connected between the lower end of the mounting arm and the support arm. The force measuring component is a torque sensor.

2. The force standard according to claim 1, characterized in that: The first sealing ring is installed on the outer periphery of the first piston and the second piston.

3. The force standard according to claim 1, characterized in that: The support includes a support base plate, a second piston fixed to the support base plate, and vertically arranged guide rods spaced apart on the support base plate. The first piston moves in coordination with each guide rod.

4. The force standard according to claim 3, characterized in that: A force sensor is installed between the support arm and the support base plate.

5. The force standard according to claim 1, characterized in that: The second piston has a center hole. The first piston includes a large-diameter section that is sealed to the rotating cylinder liner by the first sealing ring and a small-diameter section that is sealed to the center hole of the second piston by the second sealing ring. The center hole of the first piston is provided on the large-diameter section and the small-diameter section. The clearance between the large-diameter section and the rotating cylinder liner is the same as the clearance between the small-diameter section and the second piston. The first sealing ring and the second sealing ring are made of the same material.

6. The force standard according to claim 5, characterized in that: The support includes a support base plate, a second piston fixed on the support base plate, and a first guide rod and a second guide rod arranged vertically at intervals on the support base plate. The first piston moves in a guiding manner with the first guide rod and the second guide rod. The force measuring component is connected between the support base plate and the mounting arm. The bearing includes an upper bearing connected between the upper end of the mounting arm and the rotating cylinder liner, and a lower bearing connected between the lower end of the mounting arm and the support base plate.

7. A method for measuring force value using a force standard as described in any one of claims 1 to 6, characterized in that: The method includes the following steps: a force output mechanism pushes the first piston, and a cylinder liner drive mechanism drives the rotating cylinder liner to rotate at a constant speed. When the first piston does not have a center hole, the pushing force of the force output mechanism on the first piston is F=f1+PS. In the above formula, P represents the reading of the pressure sensor, S represents the effective pressure area of ​​the liquid on the first piston, and f1 represents the circumferential friction force between the first sealing ring and the rotating cylinder liner. In the formula, f1=W / 2L, W represents the torque measured by the force measuring component, and L represents the distance between the first sealing ring and the center line of the first piston. When the first piston has a central hole, the pushing force of the force output mechanism on the first piston is F = f1 + f2 + PS. In the above formula, P represents the reading of the pressure sensor, S represents the effective pressure area of ​​the liquid on the first piston, f1 represents the circumferential friction between the first sealing ring and the rotating cylinder, and f2 represents the axial friction between the second sealing ring and the second piston. In the formula, f1 = W / 2L, where W represents the torque measured by the force measuring component, L represents the distance between the first sealing ring and the center line of the first piston, and f2 = f1 * L2 / L1, where L2 represents the circumference of the second sealing ring and L1 represents the circumference of the first sealing ring.

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