Anti-deformation and correction integrated clamp for heat treatment of spiral compression spring

Abstract

The invention discloses an anti-deformation and correction integrated clamp for heat treatment of a helical compression spring, which comprises a first angle steel and a second angle steel which are oppositely arranged, one end of the first angle steel and one end of the second angle steel are hinged to the pin shaft through sleeves, and the other end of the first angle steel and the other end of the second angle steel are clamped and fixed through hexagon bolts and nuts. A plurality of through holes are evenly distributed in the two plate bodies of the first angle steel and the two plate bodies of the second angle steel in the axial direction of the spiral compression spring. The integrated clamp provided by the invention realizes multidirectional uniform constraint and correction of the helical compression spring in the quenching and tempering processes, obviously improves the product quality and the production efficiency, and has good engineering application value.

Description

Technical Field

[0001] This invention is a novel integrated clamp for preventing deformation and correcting spring heat treatment, which relates to the control of spring heat treatment deformation in the aerospace and related industries. Background Technology

[0002] Currently, helical compression springs are widely used basic components in the machinery industry, and are also used extensively and require high precision in aerospace products. In order to obtain high mechanical properties, high strength, sufficient fatigue life and small permanent deformation, while taking into account the influence of the service environment on fatigue life, strict heat treatment process control is required for helical compression springs.

[0003] The deformation of springs during heat treatment mainly originates from the thermal stress and phase transformation stress generated during heating and quenching. Simultaneously, the release of residual stress in helical compression springs, their own weight, and factors such as uneven material structure, compositional segregation, and decarburization can also exacerbate deformation. During spring cooling, different cooling rates in different parts create thermal stress. Even with the same cooling rate, the difference in cooling rates between the surface and the core can generate phase transformation stress, leading to defects such as axial bending and uneven pitch.

[0004] In particular, large-specification helical compression springs made of 65Si2MnWA steel with a wire diameter of φ11mm require a hardness of 47-52HRC after heat treatment. Deformation correction is difficult, and excessive deformation can lead to product scrap.

[0005] Traditional methods for preventing deformation typically involve using separate quenching and tempering fixtures: during quenching, multiple steel bars are used to symmetrically bind the helical compression spring, which is then simply fixed to reduce quenching deformation; before tempering, the helical compression spring is placed on a platform to find the point of maximum deformation, and V-shaped steel is used to bind and fix it at the deformation point, hoping to correct the deformation during the tempering process.

[0006] The aforementioned traditional tooling and methods have the following drawbacks: There are numerous binding points with uneven force distribution, making it impossible to achieve uniform constraint in multiple directions; the helical compression springs are still prone to bending deformation and uneven pitch during quenching and tempering; quenching and tempering require separate binding and removal, which is time-consuming and labor-intensive, requiring at least 30 minutes for each helical compression spring during quenching and tempering; significant deformation occurs after heat treatment, making correction difficult, especially for large-sized, high-hardness helical compression springs, often resulting in irreparable damage and scrap, with a pass rate of only 50%–60%; the helical compression springs have low hardness before quenching, making it easy for wires and tools to scratch and puncture the surface during binding, severely affecting surface quality and fatigue life; traditional Q235 steel bars and V-shaped steel tooling are prone to rust and deformation, resulting in a high scrap rate and requiring repeated correction and replacement, increasing production costs.

[0007] Therefore, there is an urgent need for a simple, reusable fixture that can simultaneously prevent deformation and straighten the product during quenching and tempering, in order to reduce the deformation of helical compression springs during heat treatment, improve the first-pass yield, and reduce production costs. Summary of the Invention The purpose of this invention is to overcome the shortcomings of existing technologies and provide an integrated fixture for preventing deformation and straightening during the heat treatment of helical compression springs. This fixture achieves multi-directional uniform constraint and straightening of the helical compression springs throughout the quenching and tempering process, reducing labor intensity and improving product quality and production efficiency.

[0008] To achieve the above objectives, the present invention employs the following technical solutions: An integrated clamp for heat treatment of helical compression springs to prevent deformation and straighten, the integrated clamp includes a first angle steel (2) and a second angle steel (3), the first angle steel (2) and the second angle steel (3) are both long strip angle steel structures and are arranged opposite to each other; One end of the first angle steel (2) and the second angle steel (3) is hinged to the pin (1) through a sleeve, and the other end of the first angle steel (2) and the second angle steel (3) is clamped and fixed by a hexagonal bolt and a nut (4); Multiple through holes are evenly distributed on the two plates of the first and second angle steels along the axial direction of the spiral compression spring.

[0009] The first angle steel and the second angle steel can constrain and clamp the helical compression spring from the four symmetrical directions of the outer circle generatrix of the helical compression spring, which can prevent deformation and straighten the helical compression spring during quenching and tempering.

[0010] Compared with the prior art, the present invention has the following beneficial effects: I. Effectively Improves the Shape Accuracy and Surface Quality of Helical Compression Springs After Heat Treatment: By applying symmetrical constraints from four directions along the outer circle of the helical compression spring using the first and second angle steels, the helical compression spring and the angle steels fit well together, effectively suppressing bending deformation during quenching and tempering. This keeps the pitch variation within a small range (pitch variation ≤ 0.3mm), significantly improving the straightness, perpendicularity, and pitch uniformity of the helical compression spring. During clamping, tools and the operator's hands do not directly contact the working surface of the helical compression spring, avoiding defects such as scratches and punctures caused by traditional binding methods, and significantly improving surface quality and fatigue life.

[0011] II. Significantly Improved Production Efficiency and Reduced Labor Intensity: In traditional methods, quenching and tempering require different tooling, and the spiral compression springs need to be bound and removed twice. Before tempering, deformation points must be located and bound and corrected piece by piece. The clamping time for a single spiral compression spring before and after heat treatment can reach more than 30 minutes. With the integrated fixture of this invention, the spiral compression spring only needs to be placed between two angle steels and locked with three hexagonal bolts and hexagonal nuts to complete the entire process of quenching and tempering to prevent deformation and correct it. Disassembly and assembly are convenient, and the clamping time for each spiral compression spring can be reduced to 3-5 minutes, greatly improving production efficiency.

[0012] III. Reduced Tooling and Product Scrap Costs: This invention uses heat-resistant materials such as 1Cr18Ni9Ti angle steel to manufacture fixtures. Compared to the commonly used Q235# steel, it has advantages such as better rigidity, corrosion resistance, and a higher number of reuses. Extensive product testing has shown that the fixtures remain intact, significantly reducing the tooling scrap rate. Because heat treatment deformation is effectively controlled, the first-pass yield of helical compression springs is greatly improved. Even slightly out-of-tolerance parts can meet requirements after minor corrections, resulting in an overall product pass rate close to 100%, reducing scrap losses caused by heat treatment deformation.

[0013] IV. Wide range of applications and good promotion: The clamping structure of this invention is simple and the clamping method is intuitive. In addition to being applicable to aerospace helical compression springs with a diameter of φ10~11mm, it is also highly applicable to helical compression springs of other sizes. It can be widely applied simply by adjusting the length of the angle steel and the position of the screw hole according to the size of the helical compression spring. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of a fixture for heat treatment, deformation prevention, and straightening of helical compression springs.

[0015] Figure 2 This is a schematic diagram of the first angle steel in an integrated fixture for heat treatment, deformation prevention, and straightening of helical compression springs.

[0016] Figure 3 This is a schematic diagram of the structure of the second angle steel in an integrated fixture for heat treatment, deformation prevention, and straightening of helical compression springs.

[0017] Figure 4 This is a structural diagram of a pin shaft for an integrated fixture used for heat treatment, deformation prevention, and straightening of helical compression springs.

[0018] In the diagram: 1-Pin and sleeve, 2-First angle steel, 3-Second angle steel, 4-Hexagonal nut and bolt. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings.

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] Example 1: Structure of an integrated fixture like Figures 1-4 As shown, an integrated clamp for heat treatment of helical compression springs to prevent deformation and straighten is provided. The integrated clamp includes a first angle steel (2) and a second angle steel (3). The first angle steel (2) and the second angle steel (3) are both long strip angle steel structures and are arranged opposite to each other to clamp the helical compression spring placed between them. One end of the first angle steel (2) and the second angle steel (3) are hinged to the pin (1) through a sleeve, so that the first angle steel and the second angle steel can rotate and open around the pin. The other end of the first angle steel (2) and the second angle steel (3) are clamped and fixed by a hexagonal bolt and a nut (4) to radially clamp the helical compression spring between the first angle steel and the second angle steel. Among them, multiple through holes are evenly distributed on the two plates of the first angle steel and the second angle steel along the axial direction of the spiral compression spring, which are used to ensure that the spiral compression spring is heated evenly and cooled quickly during the heat treatment process. The first and second angle steels are made of heat-resistant stainless steel 1Cr18Ni9Ti, which can prevent rust and significant deformation during quenching and tempering heat treatment.

[0022] The spacing between the through holes in the length and width directions is 15-25 mm, so that the quenching medium and furnace gas can flow through the surface of the spiral compression spring from multiple directions during the heat treatment process, ensuring that the spiral compression spring is heated evenly and cooled rapidly.

[0023] The number of hexagonal bolts and nuts (4) is three, which are separated along the axial direction of the spiral compression spring so that the first angle steel and the second angle steel can evenly clamp the spiral compression spring along the entire length of the spiral compression spring, ensuring that the clamp is tightly attached to the outer circle of the spiral compression spring.

[0024] When multiple integrated fixtures and the clamped helical compression springs are placed in the furnace, the distance between adjacent fixtures is 10-20mm. They are neatly arranged in the heat treatment furnace, ensuring uniform heating and facilitating the completion of quenching and tempering processes.

[0025] In this embodiment, the provided integrated fixture realizes multi-directional uniform constraint and correction of the helical compression spring during the quenching and tempering process.

[0026] Example 2: Based on Example 1, the method of using the integrated fixture will be further explained. This embodiment uses a helical compression spring made of 65Si2MnWA material and with a wire diameter of approximately φ11mm as an example to illustrate the usage of the integrated clamp of the present invention.

[0027] 1. Clamping: Connect the first angle steel 2 and the second angle steel 3 to the sleeve 1 via a pin, so that the two angle steels are in the open state; place the helical compression spring to be heat-treated between the two angle steels, so that the outer generatrix of the helical compression spring is basically in contact with the inner surface of the two angle steels; close the first angle steel 2 and the second angle steel 3, so that they are symmetrically close to the helical compression spring from four directions of the outer generatrix of the helical compression spring; insert three sets of standard hexagonal nuts and bolts 4 at the end away from the pin and the sleeve 1, insert them through the corresponding through holes on the first angle steel 2 and the second angle steel 3, and tighten the hexagonal nuts so that the two angle steels evenly clamp the helical compression spring along the axial direction of the helical compression spring.

[0028] 2. Heat treatment loading: The integrated fixture holding the helical compression spring is neatly placed in the heat treatment furnace, with a 10-20mm gap between adjacent fixtures to facilitate the flow of quenching medium and furnace gas; quenching heating, holding and cooling are carried out according to the established process curve to obtain the required martensitic structure of the helical compression spring; then tempering is carried out directly using the same fixture without disassembling the helical compression spring and fixture, completing the heating, holding and cooling process, and realizing continuous anti-deformation and straightening during quenching and tempering.

[0029] 3. Disassembly and Inspection: After heat treatment is completed and cooled to a safe temperature, remove the fixture from the furnace, loosen the three sets of hexagonal nuts and bolts 4 in sequence, open the first angle steel 2 and the second angle steel 3, and remove the helical compression spring from the fixture; check the pitch, straightness and perpendicularity of the helical compression spring. After heat treatment, the helical compression spring has only slight deformation and the pitch change is significantly reduced. It basically does not require or only requires a small amount of manual correction to meet the requirements of the drawing.

[0030] In this embodiment, production verification showed that after quenching and tempering heat treatment of a large number of similar helical compression springs using the integrated fixture of the present invention, the fixture itself remained intact and no obvious deformation was observed; the surface of the helical compression springs was free of binding scratches and puncture marks, the first-pass yield of the external dimensions was significantly improved, and a small number of slightly out-of-tolerance parts could meet the requirements after simple correction, resulting in a significant improvement in the overall product qualification rate.

[0031] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A fixture for heat treatment of helical compression springs to prevent deformation and for straightening, characterized in that: The integrated clamp includes a first angle steel (2) and a second angle steel (3), and the first angle steel (2) and the second angle steel (3) are arranged opposite to each other; One end of the first angle steel (2) and the second angle steel (3) is hinged to the pin (1) through a sleeve, and the other end of the first angle steel (2) and the second angle steel (3) is clamped and fixed by a hexagonal bolt and a nut (4); Multiple through holes are evenly distributed on the two plates of the first and second angle steels along the axial direction of the spiral compression spring.

2. The integrated clamp for heat treatment, deformation prevention, and straightening of helical compression springs according to claim 1, characterized in that: The first and second angle steels are made of heat-resistant stainless steel 1Cr18Ni9Ti.

3. The integrated clamp for heat treatment, deformation prevention, and straightening of helical compression springs according to claim 2, characterized in that: The spacing between the through holes in the length and width directions is 15–25 mm.

4. The integrated clamp for heat treatment, deformation prevention, and straightening of helical compression springs according to claim 2, characterized in that: The number of hexagonal bolts and nuts (4) is three, which are arranged separately along the axial direction of the spiral compression spring.

5. A fixture for heat treatment, deformation prevention, and straightening of helical compression springs according to claim 1, characterized in that: When multiple integrated clamps and the clamped helical compression springs are placed in the furnace, the distance between adjacent clamps is 10-20 mm.

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