Force measuring tool for spring with large length-diameter ratio

Abstract

The invention discloses a force measuring tool for a spring with a large length-diameter ratio, and belongs to the technical field of spring detection, the tool comprises an upper pressure head and a base, the upper pressure head comprises a thin-wall plate and a guide cylinder which are fixedly connected, the outer edge of the thin-wall plate is larger than the outer diameter of the spring to be measured, and the outer diameter of the guide cylinder is smaller than the inner diameter of the spring to be measured; the base comprises a bottom plate and a core rod which are fixedly connected, the guide cylinder and the core rod are in clearance fit and can slide mutually in the axial direction, the guide cylinder and the core rod are each of a hollow structure and interact with each other, the mass of the measuring tool pressed on a spring is greatly reduced, the measuring mode capable of obtaining an accurate result is simplified, the structure is simple, and the cost is low. The influence of the measuring tool on the spring measuring result is reduced as much as possible.

Description

Technical Field

[0001] The invention relates to the technical field of spring processing and detection, and in particular to a force measuring tool for a spring with a large aspect ratio. Background Art

[0002] For some important springs, it is necessary to ensure a stable force output under a certain amount of compression, which requires the spring to use certain methods to ensure the required force during the manufacturing process. Therefore, it is particularly important to accurately measure the force output of the spring at a specified amount of compression. Only by accurately measuring the force can the spring state be better adjusted to meet the design requirements.

[0003] For general springs, direct compression measurement can be used. Since the length-to-diameter ratio of general springs is not large, the bottom surface of the spring will provide certain support to the spring during compression to ensure the stability of the spring during compression. However, it is difficult to accurately measure the force value of a spring with a large length-to-diameter ratio using this conventional measurement method when the specified compression amount is specified. Because when a spring with a large length-to-diameter ratio is compressed downward, the downward pressure is fed back through the deformation of the spring wire to become the elastic force of the spring. Due to the spiral structure of the spring, this part of the force will be transmitted along the spiral structure of the spring, thereby forming a certain torque. However, since the bottom surface of the spring is in static contact with the lower plane of the measuring table, the downward pressure causes the friction force to increase. The torque caused by the compression of the spring cannot be reduced or eliminated by rotating the bottom surface, but can only be transformed by the torsional deformation of the spring, which will cause the spring to deform irregularly. When the compression amount reaches a large amount, the deformation of the spring will cause the center of gravity of the spring to separate from the bottom support surface of the spring, causing the spring to fly. Not only can the force value of the spring not be accurately measured, but for springs with thicker wires and larger elastic forces, it is also easy to cause injuries to personnel and damage to the instrument when they fly out.

[0004] At present, the mainstream measurement method is to use a metal measuring tool with a mandrel perpendicular to the base, pass the spring through the mandrel, place a hollow metal tube above the spring, use the pressure head to press the metal tube, and measure the compression force of the spring through the metal tube. Although this method can also measure the elastic force of the spring, it has a fatal disadvantage, that is, the greater the force value and the greater the compression, the thicker the spring diameter is, and the thicker and longer the hollow metal tube required is. Because it is generally made of stainless steel, the density of this material is large, and the mass of the metal tube is also large, often reaching several kilograms. This part of the mass will be loaded on the spring before measurement, and under the influence of this part of the mass, the spring will produce a certain compression deformation before measurement. Although this part of the influence can be minimized as much as possible through subsequent corrections, the spring is a more complex deformation process. It is difficult to accurately calculate the influence of this part of the mass by simple calculations. The cost of accurate calculation through complex simulation is too huge, and when batch measurement is performed, the stiffness of each spring will have a slight difference. Each spring needs to be accurately measured, the workload is too large, and it is very unrealistic in actual operation. Summary of the invention

[0005] The technical problem solved by the invention is to provide a force measuring tool for a spring with a light weight, high precision and large aspect ratio.

[0006] The technical solution adopted by the present invention is a force measuring tool for a spring with a large aspect ratio, comprising an upper pressure head and a base, wherein the upper pressure head comprises a fixedly connected thin-walled plate and a guide cylinder, wherein the outer edge of the thin-walled plate is larger than the outer diameter of the spring to be measured, and the outer diameter of the guide cylinder is smaller than the inner diameter of the spring to be measured, and the base comprises a fixedly connected bottom plate and a core rod, wherein the guide cylinder and the core rod are clearance-fitted and can slide against each other in the axial direction. The thin-walled plate is preferably a metal flat plate to ensure strength.

[0007] The technical solution of the present invention abandons the traditional technical solution of heavy metal tubes, and reshapes the heavy metal tube on the top into a thin metal plate to transmit pressure. The thin metal plate can be made of any metal, such as stainless steel, aluminum alloy, copper alloy, steel, etc. The thin metal plate can be in any shape, which can be circular or polygonal. If the thin metal plate is circular, the diameter should be larger than the outer diameter of the spring to be measured. If it is other polygons, it should be ensured that the spring to be measured can be completely covered. The thickness of the thin metal plate can be determined according to the size and force value of the spring to be measured, but it should not be too thick. It can be as thin as possible, and the thickness can be 0.1mm-2mm. A thin-walled metal cylinder is connected below the thin metal plate. The connection method between the metal cylinder and the thin metal plate can be welding, riveting, bonding, or integrally processed and manufactured with the thin metal plate. The wall thickness of the thin-walled metal cylinder can be very thin, which can be 0.1mm-3mm. Its outer diameter can be slightly smaller than the inner diameter of the spring, or slightly smaller than the inner diameter of the hollow core rod described below. The portion of the metal sheet in contact with the metal cylinder and located within the inner diameter of the metal cylinder can be retained or cut off to further reduce the weight.

[0008] Another part of the measuring tool is the base, which includes a bottom plate and a core rod. The bottom plate of the base is made of metal and needs to have a certain thickness and a large coverage area. The thickness and area need to be larger than the thin metal plate to ensure stability during the measurement process. The vertical projection shape of the bottom plate can be polygonal or circular. At its geometric centroid position or close to the geometric centroid position, there is a core rod vertically connected to the bottom plate. The connection method can be welding, riveting, bonding, or it can be processed and manufactured as a whole with the bottom plate. The material of the bottom plate and the core rod can use any metal, such as stainless steel, aluminum alloy, copper alloy, steel, etc. The material of the bottom plate and the core rod can be the same material or different materials. The core rod can be solid or hollow. The outer diameter of the solid core rod can be slightly smaller than the inner diameter of the above-mentioned thin-walled metal tube, the outer diameter of the hollow core rod can be slightly smaller than the inner diameter of the above-mentioned thin-walled metal tube, and the inner diameter of the hollow core rod can also be slightly larger than the outer diameter of the above-mentioned thin-walled metal tube. The relative position relationship between the thin-walled metal tube and the core shaft can be that the thin-walled metal tube is sleeved on the outside of the core shaft, or that the thin-walled metal tube is inserted into the inside of the hollow core shaft.

[0009] The beneficial effects of the present invention are that it solves the problem of measuring the elastic force value of a spring with a large length-to-diameter ratio; solves the accuracy problem of measuring the elastic force value of a spring with a large length-to-diameter ratio by the traditional method; solves the efficiency problem of measuring the elastic force value of a spring with a large length-to-diameter ratio by the traditional method; and solves the difficulty problem of measuring the elastic force value of a spring with a large length-to-diameter ratio by the traditional method; the device is simple, has strong applicability, low processing difficulty, simple measuring method, high measuring accuracy and small error. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 To measure the top plate of the tooling, Figure 2 To measure the tooling base, Figure 3 is the spring to be tested, Figure 4 The state diagram of the spring to be tested is installed on the base in a free state. Figure 5 This is the state diagram of the spring to be tested installed in the complete tooling. Figure 6 This is the state diagram when the spring is compressed to the measuring point during the measurement process. Figure 7 To measure the top plate of the tooling, Figure 8 To measure the tooling base, Fig. 9 The state diagram of the spring to be tested is installed on the base in a free state. Fig.10 This is the state diagram of the spring to be tested installed in the complete tooling. Fig.11 This is the state diagram when the spring is compressed to the measuring point during the measurement process. Markings in the figure are: 1-thin metal plate, 2-metal cylinder, 4-core rod, 101-top plate of measuring tool, 102-base, 103-spring to be measured, 104-spring in a compressed state reaching the measuring point, 105-base of measuring device, 106-pressure head of measuring device, 201-top plate of measuring tool, 202-base, 5-thin metal plate, 6-metal cylinder, 7-bottom plate, 8-core rod. DETAILED DESCRIPTION

[0011] The present invention will be further described below in conjunction with the accompanying drawings.

[0012] The invention discloses a new measuring tool, which greatly reduces the mass of the measuring tool pressed on the spring through two methods: hollowing and guiding, and simplifies the measuring method that can obtain accurate results.

[0013] Example 1 Figure 1-Figure 6 shown.

[0014] Before measuring the spring, place the tool base 102 on the measuring equipment base 105, and then string the spring 103 to be measured on the core rod 4 of the tool base 102. Figure 4 , and then place the measuring fixture top plate 101 on the upper part of the spring 103 to be tested. During the placement process, the metal cylinder 2 should be first placed on the core rod 4, and then gently placed downward through the gap between the core rod 4 and the spring 103 to be tested until the lower surface of the thin metal plate 1 is completely in contact with the upper end surface of the spring 103 to be tested. Figure 5. Start measuring, the measuring device pressure head 106 moves downward until it touches the upper surface of the tooling top plate 101, and continues to compress slowly downward until it compresses to the measuring point. Figure 6 At this time, the compressed spring 104 reaches the measuring point, and the force value displayed by the measuring device is the elastic force value of the spring at this time. After the measurement is completed, slowly raise the pressure head 106 of the measuring device to the initial position, then remove the measuring tool top plate 101 and the spring 103 to be measured, and replace the next spring for measurement. The measurement process is the same as the previous spring.

[0015] Example 2 Figure 7-Figure 1 as shown. Before measuring the spring, place the tool base 202 on the measuring equipment base 105, and then string the spring 103 to be measured on the core rod 8 of the tool base 202. Fig. 9 As shown, the measuring tool top plate 201 is placed on the upper part of the spring 103 to be tested. During the placement process, the metal cylinder 6 should be inserted into the inner center of the core rod 8 and gently placed downward until the lower surface of the thin metal plate 5 is completely in contact with the upper end surface of the spring 103 to be tested. Fig.10 . Start measuring, the measuring device pressure head 106 moves downward until it touches the upper surface of the tooling top plate 101, and continues to slowly compress downward until it is compressed to the measuring point. Fig.11 At this time, the compressed spring 104 reaches the measuring point, and the force value displayed by the measuring device is the elastic force value of the spring at this time. After the measurement is completed, slowly raise the pressure head 106 of the measuring device to the initial position, then remove the measuring tool top plate 201 and the spring 103 to be measured, and replace the next spring for measurement. The measurement process is the same as the previous spring.

[0016] The technical solution of the present invention solves the problem of inaccurate measurement results when measuring elastic force of a spring with a large aspect ratio. It can also solve the problem that a large amount of calculation or simulation work is consumed to obtain accurate measurement results of a spring with a large aspect ratio. By using a simple tooling, the influence of the measuring tooling on the spring measurement result is reduced as much as possible.

Claims

1. A force measuring tool for a spring with a large aspect ratio, characterized in that: It includes an upper pressure head and a base. The upper pressure head includes a fixedly connected thin-walled plate and a guide cylinder. The outer edge of the thin-walled plate is larger than the outer diameter of the spring to be tested, and the outer diameter of the guide cylinder is smaller than the inner diameter of the spring to be tested. The base includes a fixedly connected bottom plate and a core rod. The guide cylinder and the core rod are clearance-fitted and can slide relative to each other along the axial direction.

2. The force measuring tool for a spring with a large aspect ratio as claimed in claim 1, characterized in that: The thin-walled plate is made of metal and has a thickness of 0.1mm-2mm.

3. The force measuring tool for a spring with a large aspect ratio as claimed in claim 1, characterized in that: The guide tube is made of metal with a thickness of 0.1mm-3mm.

4. The force measuring tool for a spring with a large aspect ratio as claimed in claim 1, characterized in that: The bottom plate is made of metal material, has a thickness greater than that of the thin-walled plate, and has a larger projected area than that of the thin-walled plate.

5. The force measuring tool for a spring with a large aspect ratio as claimed in claim 1, characterized in that: The core rod is a hollow structure, and the guide tube is inserted into the inner side of the core rod and slidably matched with the core rod.

Images