JPH02121738A - Manufacture of titanium alloy spring - Google Patents

Abstract

PURPOSE:To prevent a titanium alloy from receiving creep deformation by enclosing the titanium alloy spring with molten material in a coating state or in an embedded state and age-hardening the spring in the state where the molten material is hardened to reinforce the spring. CONSTITUTION:Age hardening heat treatment is performed to the titanium alloy spring and it is left for about half an hour in the atmosphere as it is and cooled down to the normal temperature. Molten wax 5 is prepared in a wax tank 4 provided with a heater 3, a cooled titanium alloy spring 1 is dipped into the molten wax 5 to stick the wax 5 to the surface of the titanium alloy spring 1 and taken out into the atmosphere to harden the wax. While the titanium spring 1 is reinforced this reinforcing film 5A it is left in the atmosphere for 10-20 hours and age-hardened. Since the spring is reinforced, it is not deformed by creep for this treated time. Thereafter, the reinforcing film 5A is heated and removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing titanium alloy springs, and more particularly to a method for reliably preventing creep deformation during aging treatment.

[Prior art]

With steel pulp springs, which are generally used as pulp springs in the valve train of automobile engines, it is difficult to sufficiently increase their natural frequency and reduce their weight, so the followability of the valve spring in the high speed range of the engine is difficult. This delay causes a surging phenomenon, making it difficult to sufficiently increase the engine's rotational limit. As this surging prevention technology, for example, Japanese Utility Model Application Publication No. 50-113708 discloses that a cap is provided at the upper end of the valve stem, interposed between the cam and the stem, and surrounding the outside of the upper end of the pulp spring. It is described that an elastic body is interposed between the surface and the outer periphery of the upper end of the valve spring, and the elastic body is used to prevent surging.

By the way, hollow springs, springs with different diameter cross sections, springs with different coil diameters, titanium alloy springs, etc. are known as springs that can be made lighter. Among these various springs, titanium alloy springs are considered the most promising as pulp springs due to their high specific stiffness and specific strength, but when manufacturing titanium alloy springs, aging heat treatment is required after forming them into a predetermined spring shape. During the aging-hardening process at room temperature, creep deformation is likely to occur due to its own weight, making it unsuitable for mass production and difficult to reduce manufacturing costs.

As a technique for preventing the above-mentioned creep deformation when manufacturing the above-mentioned titanium alloy spring, a technique is known in which a titanium alloy spring is mounted on a horizontal rotating shaft and the spring is aged and hardened while being rotated by the rotating shaft.

[Problems to be Solved by the Invention] As described above, when manufacturing titanium alloy springs, it is possible to prevent creep deformation by age hardening the titanium alloy spring while holding it in a horizontal position and rotating it. However, age hardening takes at least 5 to 10 hours, so if you want to rotate a spring for such a long time and mass produce valve springs, etc., the equipment cost for the rotating equipment will be large, and the manufacturing process will be slow. The problem is that the cost is very high.

An object of the present invention is to provide a method for manufacturing a titanium alloy spring that can reliably prevent creep deformation during age hardening, which is suitable for mass production and at a low cost.

[Means for Solving the Problems] The method for manufacturing a titanium alloy spring according to the present invention includes subjecting a titanium alloy spring formed into a predetermined shape to an aging heat treatment, and then coating or coating the spring with a molten wrapping material. The spring is wrapped in an embedded state, and then the wrapping material is solidified to strengthen the spring, and the spring is age-hardened. After the spring is aged, the wrapping material is removed.

[Function] In the method for manufacturing a titanium alloy spring according to the present invention, a titanium alloy spring formed into a predetermined shape is subjected to an aging heat treatment, and then the spring is wrapped in a molten wrapping material in a coating or embedded manner, The spring is then age hardened with the encasing material solidified and the spring reinforced. Therefore, during age hardening, the titanium alloy spring remains sufficiently reinforced by the solidified enveloping material to prevent creep deformation.

〔Effect of the invention〕

According to the method for manufacturing a titanium alloy spring according to the present invention, as explained above, the titanium alloy spring is age-hardened while being reinforced with a wrapping material that is wrapped in a coating or embedded shape and solidified. , it is possible to reliably prevent creep deformation during age hardening.

In addition, it is also possible to use wax or synthetic resin materials as wrapping materials, and when using these materials to wrap titanium alloy springs in a coating, it can be done with very simple and inexpensive equipment, making it suitable for mass production. It can be carried out at low cost, and even when the titanium alloy spring is embedded in wax, it can be carried out with relatively simple and inexpensive equipment.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

<First Example> (See Figures 1 (a) to (d)) In this example, the present invention is applied to manufacture a titanium alloy spring used as a pulp spring for a valve mechanism of an automobile engine. This is an example.

For example, the material of the titanium alloy spring is 3% by weight.
Using a titanium alloy containing % A1 and 2.5% ■,
A titanium alloy spring is manufactured through the following first to sixth steps.

In the first step, a wire rod of a predetermined thickness made of the titanium alloy material is formed into a predetermined spring shape by a known method.

Next, in the second step, as shown in FIG. 1(a),
The titanium alloy spring 1 obtained by the above molding is housed in a heating furnace 2, and subjected to a compacting treatment, that is, an aging heat treatment, for 700 min.
Heat to a temperature of ~800°C and hold for at least 5 minutes.

Next, in the third step, the titanium alloy spring 1 subjected to the container treatment is taken out from the heating furnace 2, and left in the atmosphere for about 30 minutes to cool to about room temperature.

Next, in the fourth step, as shown in FIG. 1(b),
Wax 5 is prepared in a molten state (at a temperature of 40 to 80°C) in a Wanks tank 4 equipped with a heater 3, and the cooled titanium alloy spring 1 is immersed in the molten wax 5 to form the titanium alloy spring 1. Wax 5 is applied to the surface to a thickness of about 0.5 mm.

Next, in the fifth step, as shown in FIG. 1(C),
The titanium alloy spring 1 is taken out into the atmosphere from the molten wax 5, and the wax 5 adhering to the entire surface of the titanium alloy spring 1 is fixed, so that the entire surface of the titanium alloy spring 1 has about 0.5
A reinforcing film 5A with a thickness of mm is formed, and the titanium alloy spring 1 is reinforced with this reinforcing film 5A and exposed to the atmosphere for about 10 to 10 minutes.
Leave to stand for 20 hours for age hardening treatment. As mentioned above, since the age hardening treatment is performed with the reinforcing film 5A of solidified wax 5 having a film thickness of about 0.5 mm formed on the surface of the titanium alloy spring 1, the titanium alloy spring 1 is treated with the reinforcing film 5A. Since it is reinforced and has high rigidity, it will not undergo creep deformation during age hardening treatment.

However, to form the reinforcing film 5A, the wax 5 in a molten state may be applied to the surface of the titanium alloy spring 1 by spraying or coating and then solidified, but the reinforcing film 5A with a uniform thickness may be formed. This is desirable. Further, the thickness of the reinforcing film 5A is approximately 0.
It may be larger than 5 mm.

Next, in the sixth step, as shown in FIG. 1(d),
The titanium alloy spring 1 with the reinforcing film 5A is placed in a low-temperature heating furnace 7 equipped with a heater 6 and heated to about 100°C, and the wax 5 forming the reinforcing film 5A is melted to form the titanium alloy spring 1. removed from the surface. However, in this case, the molten wax 5 may be scattered by air blowing if necessary. As a method for removing the wax 5, a method of blowing hot air or a method of pouring hot water may also be adopted.

Note that paraffin or microwax is used as the material for the wax 5.

According to the method for manufacturing a titanium alloy spring according to the above embodiment, creep deformation of the titanium alloy spring 1 during age hardening treatment can be reliably prevented by a simple method. Moreover, creep deformation can be prevented using simple and inexpensive equipment and materials such as the wax tank 4, the low-temperature heating furnace 7, and the wax 5. In addition, no treatment is required during the long-term age hardening process, so
This manufacturing method is suitable for mass-producing the titanium alloy spring 1.

Second Example (See Figures 2(a) to (e)) Similar to the first example, this example is for manufacturing a titanium alloy spring as a valve spring for a valve mechanism of an automobile engine. This is an example in which the present invention is applied to a titanium alloy spring 1 using a wire rod made of the same titanium alloy material as described above and performing the following first to seventh steps.

The first to third steps are the same as those in the first embodiment, so their explanation will be omitted.

In the fourth step, as shown in FIG. 2(b), wax 5 is prepared in a molten state (approximately 40 to 80°C) in a wax tank 4 equipped with a heater 3, and heated to room temperature after aging heat treatment. The cooled titanium alloy spring 1 is immersed in molten wax 5 in a wax bath 4.

Next, in the fifth step, as shown in FIG. 2(C),
With the titanium alloy spring 1 immersed in the wax 5 in the wax tank 4, the heater 3 is stopped and heat is radiated into the atmosphere to cool and solidify the wax 5, and the titanium alloy spring 1 is immersed in the solidified wax 5. The titanium alloy spring 1 is wrapped in an embedded state, reinforced with the wax 5, and the titanium alloy spring 1 is reinforced with the solidified Fuchs 5, and the titanium alloy spring 1 is kept at room temperature for about 10 to 20 hours, preferably about 24 hours. Leave it for an age hardening treatment. As described above, during age hardening, the titanium alloy spring 1 is embedded and reinforced in the solidified wax 5, so that it does not undergo creep deformation during age hardening.

Next, in the sixth step, as shown in FIG. 2(d),
After the heater 3 of the wax tank 4 is operated to melt the wax 5, the titanium alloy spring 1 is taken out into the atmosphere.

Next, in the seventh step, the titanium alloy spring 1 is removed from the cleaning tank 8.
By spraying a solvent 10 such as trichloride, kerosene, or hexane onto the titanium alloy spring 1 from a nozzle 9, the wax 5 adhering to the surface of the spring 1 is melted and removed by the solvent 10.

This seventh process is performed after the sixth process by waxing the surface of the spring 1.
If this is done before the wax has solidified, the wax 5 can be removed efficiently.

According to the manufacturing method of the titanium alloy spring of this embodiment, as in the case of the first embodiment, creep deformation during the age hardening treatment of the titanium alloy spring 1 can be reliably prevented, and creep deformation can be prevented using simple and inexpensive equipment. It can be prevented.

Moreover, mass production can be supported simply by increasing the size of the wax tank 4. In particular, since the titanium alloy spring 1 is held embedded in the solidified wax 5 during the age hardening treatment, the shape of the titanium alloy spring 1 can be reliably maintained without being affected by the external temperature.

Third Embodiment (See Figures 3(a) to 3(d)) Similar to the first embodiment, this embodiment is for manufacturing a titanium alloy spring as a valve spring for a valve mechanism of an automobile engine. This is an example in which the present invention is applied to a titanium alloy spring using the same titanium alloy material as described above and performing the following first to sixth steps.

The first to third steps are the same as those in the first embodiment, so their explanation will be omitted.

In the fourth step, as shown in FIG. 3(b), a molten synthetic resin 12 (
Spray out acrylic resin, epoxy resin, etc.
Coat the entire surface to a thickness of about 0.3M.

Next, in the fifth step, as shown in FIG. 3(C),
The synthetic resin 12 on the surface of the titanium alloy spring 1 is dried in the atmosphere to solidify it, and a reinforcing film 12A with a thickness of approximately 0.3 is formed on the surface of the titanium alloy spring 1. The reinforced alloy spring 1 is left in the atmosphere for about 10 to 20 hours to undergo age hardening treatment.

The spring 1 is reinforced with a reinforcing film 12A made of solidified synthetic resin and has increased rigidity, so that it will not undergo creep deformation during the age hardening process.

Next, in the sixth step, as shown in FIG. 3(d),
The titanium alloy spring 1 is placed in a cleaning tank 8, and a solvent IO such as acetone or thinner is jetted over the entire spring 1 from a nozzle 9 to dissolve and remove the reinforcing film 12A. However, the reinforcing film 12A may be removed by immersing the spring 1 in the solvent 10.

According to the manufacturing method of the titanium alloy spring of this embodiment, creep deformation can be reliably prevented using extremely simple equipment without using any special equipment, and for the same reason as the first embodiment, it is particularly suitable for mass production. Are suitable.

Although the first to third embodiments are directed to the spring 1 made entirely of titanium alloy material, it is possible to combine the titanium alloy material and steel material as shown in FIGS. 4 to 7. The present invention can also be applied to the production of titanium alloy springs IA to ID. These titanium alloy springs IA-ID are all for use in valve springs, and springs IA-ID are used to reduce the weight of the upper end of the valve mechanism near the cam.
The upper end side has more titanium alloy material, and the lower end side of springs IA~ID has more steel material, and springs IA~ID
The movable part on the upper end side is made lighter, the natural frequency of the springs IA to ID is increased, and surging is damped using a titanium alloy material with high specific rigidity and high damping performance.

The titanium alloy spring IA shown in FIG. 4 has a cylindrical joint surface between a titanium alloy wire 20 on the outer circumferential side whose cross section gradually decreases toward the lower end and a steel wire rod 21 on the inner circumferential side whose cross section gradually increases toward the lower end. The two are bonded together by diffusion bonding.

The titanium alloy spring IB shown in FIG. 5 has a steel wire rod 23 that is gradually thicker toward the lower end embedded in the center of a titanium alloy wire rod 22, and has such a structure at the manufacturing stage of the wire rod.

In the titanium alloy spring IC shown in FIG. 6, a steel wire rod 25 that gradually becomes thicker toward the lower end is embedded and integrated into the lower end portion of the titanium alloy wire rod 24.

In the titanium alloy spring ID shown in FIG. 7, steel wires 27 whose number gradually increases toward the lower end are integrally embedded in the center of a titanium alloy wire 26.

However, titanium alloy spring IA with the structure shown in FIGS. 4 to 7 above
~ID, if sufficient rigidity can be obtained with the steel wires 21, 23, 25 and the steel wire 27, there is a possibility that reinforcement with wax or synthetic resin to prevent creep deformation can be omitted.

[Brief Description of the Drawings] The drawings relate to embodiments of the present invention, and include FIGS.
d) is a process explanatory diagram illustrating each step of the titanium alloy spring manufacturing method of the first embodiment, and FIGS. 2(a) to (e) are process diagrams of the titanium alloy spring manufacturing method of the second embodiment, respectively. FIGS. 3(a) to 3(d) are process explanatory diagrams illustrating each process of the titanium alloy spring manufacturing method of the third embodiment, respectively.
4 to 7 are cross-sectional views of titanium alloy springs according to modified examples, respectively. Fig. 4 1・IA・IB・IC-ID・・Titanium alloy spring, 5・
・Wax, 5A...Reinforcement film, 12...Synthetic resin, 12A...Reinforcement film. Patent applicant Mazda Motor Corporation (a) (b) (C) (d) (a) (b) Figure 2 (c) (C) ■ (d) (d) (e)

Claims (1)

[Claims] (1) A titanium alloy spring that has been formed into a predetermined shape is subjected to aging heat treatment, then the spring is wrapped in a molten wrapping material in a coating or embedded manner, and then the wrapping material is solidified to reinforce the spring. A method for manufacturing a titanium alloy spring, comprising aging hardening the spring, and removing the encasing material after the aging of the spring is completed.