Pre-deformation spring steel wire, preparation method thereof, strong-pressure-free spring and preparation method of strong-pressure-free spring

Abstract

The invention discloses a pre-deformation spring steel wire and a preparation method thereof as well as a strong-pressure-free spring and a preparation method thereof, and relates to the technical field of mechanical engineering. Comprising the steps of applying a tensile load and a torsional load to a straightened raw steel wire, heating, preserving heat and shaping. The raw material steel wire is pre-deformed, and the internal dislocation bending movement direction of the raw material steel wire is pre-adjusted, so that the raw material steel wire has the capability of resisting further torsional deformation in advance. The compression spring is manufactured by adopting the pre-deformed spring steel wire, so that the rapid stress relaxation process of the compression spring can be effectively shortened or eliminated, and the effect of avoiding the strong pressure treatment process is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical engineering, and in particular to a pre-deformed spring steel wire and a preparation method thereof, a compression-free spring and a preparation method thereof. Background Art

[0002] Cylindrical helical compression springs are a widely used type of spring. To maintain a relatively stable load, compression springs used in critical applications often undergo stress treatment. A common stress treatment method is thermal stress treatment, where the spring is compressed and tightened for a period of time, or held under heated conditions for a period of time. Other stress treatment methods include electrical stress treatment. Typically, the initial length of springs after stress treatment varies significantly, with a wide distribution. The spring's condition also varies significantly, with some springs experiencing rapid stress relaxation upon entering service, while others appear overstressed.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The object of the present invention is to provide a pre-deformed spring steel wire and a preparation method thereof, a compression-free spring and a preparation method thereof.

[0005] The present invention is achieved in that:

[0006] In a first aspect, the present invention provides a method for preparing a pre-deformed spring steel wire, comprising applying a tensile load and a torsional load to a straightened raw steel wire and heating and heat-insulating to shape the wire.

[0007] The tensile load satisfies the formula:

[0008] The torsional load satisfies the formula: T=0.5PD.

[0009] Where F is the tensile load in N; T is the torsional load in N·m; P is the maximum load of the spring to be manufactured in N; D is the mean diameter of the spring to be manufactured in m; and d is the diameter of the raw steel wire in m.

[0010] In an optional embodiment, the raw steel wire includes carbon spring steel wire or alloy spring steel wire.

[0011] In an optional embodiment, the temperature at which the carbon spring steel wire is heated and kept warm is 150°C to 180°C.

[0012] In an optional embodiment, the temperature at which the alloy spring steel wire is heated and kept warm is 180°C to 200°C.

[0013] In an optional embodiment, the insulation time is 2 hours to 4 hours.

[0014] In an optional embodiment, the torsional direction of the torsional load is determined according to the rotation direction of the spring to be manufactured, and a right-handed torsional load is applied to a right-handed spring, and a left-handed torsional load is applied to a left-handed spring.

[0015] In a second aspect, the present invention provides a pre-deformed spring steel wire, which is produced by the production method of any one of the aforementioned embodiments.

[0016] In a third aspect, the present invention provides a method for preparing a compression-free spring, comprising winding the aforementioned pre-deformed spring steel wire and then performing a tempering treatment.

[0017] In a fourth aspect, the present invention provides a compression-free spring, which is manufactured by the preparation method of the aforementioned embodiment.

[0018] The present invention has the following beneficial effects:

[0019] The present invention provides a pre-deformed spring steel wire and a method for making the same, as well as a compression-free spring and a method for making the same. By pre-deformation of the raw steel wire, the bending direction of internal dislocations in the raw steel wire can be pre-adjusted, pre-equipping the raw steel wire with the ability to resist further torsional deformation. The compression-free spring, made from pre-deformed spring steel wire, effectively shortens or eliminates the rapid stress relaxation process of the compression spring, eliminating the need for a compression process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a physical picture of the compression-free spring prepared in Example 3;

[0022] Figure 2 This is a physical picture of the pressure-free spring prepared in Example 4. DETAILED DESCRIPTION

[0023] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0024] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0025] The stress relaxation of springs is divided into two stages: rapid relaxation and slow relaxation. Springs are made of steel wire, which is usually formed by cold drawing. Under the action of tensile load, the dislocations inside the steel wire will bend to resist further axial tensile deformation. However, in the process of preparing the spring, after the cold-drawn steel wire is wound into a cylindrical helical compression spring, the load borne by the spring steel wire is mainly torsional load and bending load, rather than axial tensile load. Under the action of the new load, the bending movement direction of the dislocations inside the steel wire needs to be adjusted to resist the deformation caused by the new load. Among them, the process of adjusting the bending direction of the dislocations is the rapid relaxation process of stress. The strong pressure treatment commonly used at present can adjust the bending direction of the dislocations inside the steel wire, thereby helping to eliminate the rapid relaxation process of stress.

[0026] Commonly used stress treatment methods include thermal stress treatment and electrical stress treatment. Thermal stress treatment involves compressing and tightening the spring and then holding it for a period of time, or maintaining it under heated conditions for a period of time. However, the initial length of the springs after stress treatment varies greatly, with a wide distribution range and significant variability in spring condition. Some springs are insufficiently stress-treated and still experience rapid stress relaxation after entering the working state, while others are over-stressed. Therefore, the inventors propose the following solution.

[0027] In a first aspect, the present invention provides a method for preparing a pre-deformed spring steel wire, comprising applying a tensile load and a torsional load to a straightened raw steel wire and heating and heat-insulating to shape the wire.

[0028] The tensile load satisfies the formula:

[0029] The torsional load satisfies the formula: T=0.5PD.

[0030] Where F is the tensile load in N; T is the torsional load in N·m; P is the maximum load of the spring to be manufactured in N; D is the mean diameter of the spring to be manufactured in m; and d is the diameter of the raw steel wire in m.

[0031] The inventors found that although strong pressing treatment can eliminate the rapid relaxation stage of the spring, the strong pressing process is limited to the compression and tightening of the steel wire, resulting in each spring being subjected to different bending stresses and torsional loads during the strong pressing process, resulting in the springs after strong pressing treatment being of different lengths and uneven quality.

[0032] The present invention applies tensile load and torsional load to the raw steel wire and heats and insulates the wire for shaping, so that the load at each location of the raw steel wire is uniform during the loading process, thereby obtaining a pre-deformed spring steel wire. The overall length of the spring made from the pre-deformed spring steel wire is within an error range and has excellent quality.

[0033] In an optional embodiment, the raw steel wire includes carbon spring steel wire or alloy spring steel wire.

[0034] In an optional embodiment, the temperature at which the carbon spring steel wire is heated and kept warm is 150°C to 180°C, for example, it can be any value among 150°C, 155°C, 160°C, 165°C, 170°C, 175°C or 180°C, or a range consisting of any two values.

[0035] In an optional embodiment, the temperature at which the alloy spring steel wire is heated and kept warm is 180°C to 200°C, for example, it can be any value among 180°C, 185°C, 190°C, 195°C or 200°C, or a range consisting of any two values.

[0036] In an optional embodiment, the holding time is 2 hours to 4 hours, for example, it can be any value of 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours, or a range value consisting of any two values.

[0037] In an optional embodiment, the torsional direction of the torsional load is determined according to the rotation direction of the spring to be manufactured. For example, if a right-handed spring is manufactured, a right-handed torsional load is applied, and if a left-handed spring is manufactured, a left-handed torsional load is applied.

[0038] In a second aspect, the present invention provides a pre-deformed spring steel wire, which is produced by the production method of any one of the aforementioned embodiments.

[0039] The pre-deformed spring steel wire can be used to manufacture springs with higher performance requirements.

[0040] In a third aspect, the present invention provides a method for preparing a non-forced compression spring, comprising winding the pre-deformed spring wire of the aforementioned embodiment and then subjecting it to a tempering treatment. This non-forced compression spring, which does not require a forced compression treatment, exhibits excellent stability and is suitable for applications requiring high spring performance.

[0041] In a fourth aspect, the present invention provides a compression-free spring, which is manufactured by the preparation method of the aforementioned embodiment.

[0042] Example 1

[0043] This embodiment provides a pre-deformed spring steel wire. The pre-deformed spring steel wire is made of 60Si2MnA spring steel wire with a diameter of 5 mm. The pre-deformed spring steel wire is cut into short steel wires of 2200 mm in length and straightened for later use.

[0044] The maximum load of the compression-free spring to be manufactured is 650N, the length is 100mm, the middle diameter is 50mm, and the spiral direction is right-hand.

[0045] This embodiment also provides a method for preparing the above-mentioned pre-deformed spring steel wire, comprising the following steps:

[0046] Calculate the tensile load applied to the steel wire in this embodiment as

[0047] The torsional load that needs to be applied to the steel wire in this embodiment is calculated to be T=0.5PD=0.5×650×0.05=16.25 N·m.

[0048] One end of the straightened raw steel wire was fixed and suspended vertically in a tube furnace. An axial tensile load of 26,000 N and a counterclockwise torsional load of 16.25 N·m were applied to the lower end of the raw steel wire. The effective length of the torsional load section was 2,000 mm. The tube furnace was then heated to 200°C and held at that temperature for 2 hours. The pre-deformed spring steel wire was then produced by cooling in the furnace.

[0049] In this embodiment, a total of 200 sections of raw steel wire were pre-deformed.

[0050] Example 2

[0051] This embodiment provides a pre-deformed spring steel wire. The pre-deformed spring steel wire is made of 65Mn steel wire with a diameter of 4 mm. The pre-deformed spring steel wire is cut into short steel wires of 2000 mm in length and straightened for standby use.

[0052] The maximum load of the compression-free spring to be manufactured is 560N, the length is 80mm, the middle diameter is 26mm, and the spiral direction is right-hand.

[0053] This embodiment also provides a method for preparing the above-mentioned pre-deformed spring steel wire, comprising the following steps:

[0054] Calculate the tensile load applied to the steel wire in this embodiment as

[0055] The torsional load that needs to be applied to the steel wire in this embodiment is calculated to be T=0.5PD=0.5×560×0.026=7.28 N·m.

[0056] One end of the straightened raw steel wire was fixed and suspended vertically in a tube furnace. An axial tensile load of 14,560 N and a counterclockwise torsional load of 7.28 N·m were applied to the lower end of the raw steel wire. The effective length of the torsional load section was 1,800 mm. The tube furnace was then heated to 180°C and held at that temperature for 3 hours. The pre-deformed spring steel wire was then produced after cooling in the furnace.

[0057] In this embodiment, a total of 100 sections of raw steel wire were pre-deformed.

[0058] Example 3

[0059] This embodiment provides a compression-free spring with a length of 100 mm, a median diameter of 50 mm, a total number of coils of 4, an effective number of coils of 2, a right-hand spiral direction, and a pre-deformed spring wire diameter of 5 mm.

[0060] The preparation method comprises: using 200 sections of pre-deformed spring steel wire in Example 1 to wind into 391 springs, and after tempering treatment, obtaining the following Figure 1 The shown free compression spring.

[0061] Example 4

[0062] This embodiment provides a compression-free spring with a length of 80 mm, a median diameter of 26 mm, a total number of coils of 10, an effective number of coils of 8, a right-hand spiral, and a pre-deformed spring wire diameter of 4 mm.

[0063] The preparation method comprises: using 100 sections of pre-deformed spring steel wire in Example 2 to wind into 195 springs, and after tempering treatment, obtaining the following Figure 2 The shown free compression spring.

[0064] Comparative Example 1

[0065] This comparative example provides a spring. The size parameters of the spring to be manufactured are the same as those of Example 3. It is made of the same raw steel wire as Example 1 that has not been pre-deformed and is tempered, with a total of 20 pieces.

[0066] Comparative Example 2

[0067] This comparative example provides a spring, the size parameters of the spring to be manufactured are the same as those of Example 4, and it is made of the same raw steel wire as Example 2 that has not been pre-deformed and is tempered, with a total of 20 pieces.

[0068] Test Example 1

[0069] This test example tests the residual deformation of the pre-deformed spring steel wires in Example 1 and Example 2, and obtains the results shown in Table 1.

[0070] The indexing angle is recorded on the torque-applying device. After applying an axial tensile load to the raw steel wire, a torsional load is applied until it reaches the set value. The torsional load is then unloaded, and the torsional load is applied a second time to the set value, and then unloaded again. A pointer is set on the test bench, aligned with the zero position of the indexing angle, and a torsional load is applied a third time until it reaches the designed value. The temperature is raised, held, and cooled in the furnace. The torsional load is then unloaded, and the pointer position reading is recorded. This reading is the residual deformation (expressed as an angle value).

[0071] Table 1 Properties of pre-deformed spring steel wire

[0072]

[0073]

[0074] Test Example 2

[0075] In this test example, the springs prepared in Example 3, Example 4, Comparative Example 1, and Comparative Example 2 were subjected to a forced compression treatment. The deformation caused by the forced compression treatment was measured and expressed as a change in spring length. The results are shown in Table 2. The number of springs tested in each example and comparative example was 20.

[0076] Table 2 Performance of the free-pressure spring

[0077] High pressure treatment conditions Spring length change after strong pressure / mm Example 3 180℃×2h 0.2-0.3 Example 4 180℃×3h 0.3-0.5 Comparative Example 1 180℃×2h 3.6-5.1 Comparative Example 2 180℃×3h 1.5-2.7

[0078] Comparing the test results of Example 3 with those of the comparative example, and of Example 4 with those of Comparative Example 2, it can be seen that the springs manufactured using unpre-deformed wire experience significant length changes during the compression treatment, with the changes varying widely. However, the compression-free springs manufactured using the pre-deformed spring wire provided by the present invention exhibit essentially unchanged length changes after compression treatment, within the measurement error range. This demonstrates that using pre-deformed spring wire to manufacture compression springs can achieve the desired compression-free effect.

[0079] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a pre-deformed spring steel wire, characterized in that: The process includes applying tensile load and torsional load to the straightened raw steel wire and heating and heat-insulating to set the wire; The tensile load satisfies the formula: The torsional load satisfies the formula: T = 0.5PD; Where F is the tensile load in N; T is the torsional load in N·m; P is the maximum load of the spring to be manufactured in N; D is the mean diameter of the spring to be manufactured in m; and d is the diameter of the raw steel wire in m.

2. The preparation method according to claim 1, characterized in that The raw steel wire includes carbon spring steel wire or alloy spring steel wire.

3. The preparation method according to claim 2, characterized in that The temperature at which the carbon spring steel wire is heated and kept warm is 150° C. to 180° C.

4. The preparation method according to claim 2, characterized in that The temperature at which the alloy spring steel wire is heated and kept warm is 180° C. to 200° C.

5. The preparation method according to any one of claims 1, 3 or 4, characterized in that The insulation time is 2h to 4h.

6. The preparation method according to claim 1, characterized in that The direction of the torsional load is determined according to the rotation direction of the spring to be manufactured. A right-handed torsional load is applied to a right-handed spring, and a left-handed torsional load is applied to a left-handed spring.

7. A pre-deformed spring steel wire, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 6.

8. A method for preparing a spring without strong pressure, characterized in that: After the pre-deformed spring steel wire according to claim 7 is wound, it is subjected to tempering treatment.

9. A spring free from strong pressure, characterized in that: Prepared by the preparation method according to claim 8.

Images