JPH04181029A - Production of thrust plate for viscous coupling - Google Patents

Abstract

PURPOSE:To increase durability of a viscous coupling by chemically polishing surfaces of thrust plate members formed of a low-carbon steel plate press- stamped, and then surface treating the members to form soft nitride layer and oxide layer. CONSTITUTION:An outer plate member 1 and an inner plate member 2 of specified shapes are respectively formed by press-stamping a low carbon steel plate. Then, both plate members 1,2 are chemically polished in an ordinary manner by use of a chemical polishing liquid consisting of hydrogen peroxide, hydrogen ammonium difluoride, or the like, so that burrs and also foreign matters on the plate members 1,2 are removed. Subsequently, a soft nitride layer and an oxide layer are formed in the atmosphere of N2, NH3 and CO2 by a vacuum deposition apparatus. Consequently, the wear resistance is increased and the gelation of silicone oil is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a thrust plate used in a viscous coupling.

[Conventional technology]

BACKGROUND ART Conventionally, viscous couplings have been known that transmit torque by utilizing shearing of a high viscosity fluid (silicone oil). As shown in FIG. 17, this viscous coupling consists of a housing 3, a shaft 4 fitted into a housing 8, and a spacer ring 5 which are arranged at intervals in the axial direction. A plurality of outer plates 6 whose outer peripheries are loosely fitted to the inner circumferential spline portion of the housing 3; and a plurality of inner plates arranged between the outer plates 6 and whose inner circumferences are loosely fitted to the outer circumferential spline portion of the shaft 4. 7, and inside the housing 3 there are 80 to 90
% silicone oil (viscosity 5000-200000cS
t) and 10-20% air is enclosed.

In this viscous coupling, when a rotation difference occurs between the housing 3 and the shaft 3, the same rotation difference occurs between the outer and inner plates 6 and 7 loosely fitted to each spline part, and the Torque is generated by shearing the high viscosity silicone oil. The differential is configured to be limited by this torque.

The conventional outer and inner plates (thrust plates) 6.7 used here are formed by press-punching a low carbon steel plate with a surface roughness of about 5 to 7 μRz into a predetermined shape, and the surface has a 20 to 30 μm roughness. Soft nitrided layer and 5 μm
A surface layer consisting of the following oxidized layer is provided: This surface layer improves the wear resistance of the outer and inner plates 6.7.

Furthermore, Japanese Patent Application Laid-Open No. 61-236932 discloses that in order to achieve torque characteristics that are as constant as possible over the entire service life of the outer and inner plates, the average surface roughness is A manufacturing method is disclosed that achieves the depth value and the cross-sectional depth within a predetermined range.

[Problem to be solved by the invention]

By the way, in the above-mentioned viscous coupling, in order to keep the transmitted torque constant and prolong its life, it is preferable that the viscosity of the silicone oil sealed in the housing 3 be kept almost constant.

However, when this silicone oil is contaminated with abrasion particles and foreign matter as it is used, it becomes gelled and its viscosity increases.

The above-mentioned conventional outer and inner plates 6.7 have a surface layer made of a nitrocarburized layer and an oxidized layer on their surfaces to improve wear resistance, but it is desirable to further improve the wear resistance. .

The present invention has been devised in view of the above circumstances, and its technical object is to provide a method for manufacturing a thrust plate that can prevent gelation of silicone oil and further improve the durability of a viscous coupling. There is a particular thing.

[Means to solve the problem]

The method for manufacturing a thrust plate according to the present invention includes a punching step of press-punching a low carbon steel plate to form a thrust plate material of a predetermined shape, and a surface step of sequentially forming a nitrocarburized layer and an oxidized layer on the surface of the thrust plate material. The method for manufacturing a thrust plate for a viscous coupling, which includes a treatment step, is characterized in that after the punching step, the surface treatment step is performed through a chemical polishing step of polishing the surface of the thrust plate material. .

In other words, as a result of research conducted by the present inventors, the present invention has found that performing a chemical polishing process before a surface treatment process for forming a surface layer on a thrust plate material having an extremely fine surface roughness on the order of μ can improve the thrust plate material's surface roughness. This was completed based on the discovery that it was extremely effective in improving the wear resistance of plates.

[Effect]

In the manufacturing method of the present invention, by performing a chemical polishing step, fine particles and foreign matter on the surface formed during punching of the thrust plate material are removed, and the surface is smoothed. As a result, the thickness of the nitrocarburized layer and oxidized layer formed in the subsequent surface treatment process is made uniform, and the surface is smoothed, thereby suppressing the generation of wear powder and foreign matter from the thrust plate. it is conceivable that. This results in
Gelation of silicone oil is prevented, and the durability of the viscous coupling can be further improved.

【Example〕

The present invention will be explained in detail below.

The method for manufacturing a thrust plate of this embodiment is to sequentially perform a punching process, a chemical polishing process, and a surface treatment process to form an outer plate and an inner plate.

First, in the punching process, the thickness was 0.4 mm and the surface roughness was 5.
A low carbon steel plate of ~7μRz was prepared and punched out using a press machine to form an outer plate material 1 and an inner plate material 2 having predetermined shapes as shown in FIGS. 1 and 2, respectively.

The next chemical polishing step was performed according to the process diagram shown in FIG. First, the outer and inner plate materials 1.2 were immersed in Triclean for 5 minutes to perform a degreasing treatment, and after washing with water, the outer and inner plate materials 1.2 were subjected to a chemical polishing treatment.

In this chemical polishing process, a 3-fold dilution of a commercially available chemical polishing solution (25% hydrogen peroxide, 11% ammonium hydrogen difluoride, etc.) was used for 90 seconds for outer plate material 1, and for approximately 60 seconds for inner plate material 2. seconds at room temperature (10~
30° C.) in the chemical polishing solution.

As a result, the edges of the outer and inner plate materials 1.2 formed in the punching process were removed, and foreign matter on their surfaces was also removed to smooth the surfaces. After that, wash the outer and inch plate material 1.2 with 10% HC.
After pickling with I aqueous solution and washing with water, further 10% Na
It was neutralized with an OH aqueous solution and washed with water.

In the next surface treatment process, a vacuum evaporation device is used to perform N! ,
NH*, COx atmosphere, vacuum degree 500T.

The outer and inner plate materials 1.2 were left in a vacuum layer under the conditions of rr and temperature of 550 to 650° C., and a 20 to 30 μm soft nitrided layer was formed on their surfaces. Then, during cooling, air is introduced to oxidize, and the surface of the soft nitrided layer is coated with a thickness of 5 μm.
The following oxide layers were formed.

The outer and inner plates manufactured as described above have a chemical polishing process to remove particles and foreign substances on the surface and smooth the surface, so the soft nitrided layer and oxidized layer are formed in the surface treatment process. has been made uniform and its surface has been smoothed.

This reduces the amount of wear powder and foreign matter generated from the outer and inner plates, prevents silicone oil from gelling, and improves the durability of the viscous coupling. This excellent effect was confirmed through tests.

(Test 1) A large number of each of the outer and inner plate materials obtained through the punching process of the above example was prepared, and changes in the height of the paris, changes in surface roughness, and changes in surface shape due to the chemical polishing treatment were performed. I looked into it.

(1) Change in Paris Height First, when examining changes in Paris height, the occurrence of Paris on the outer and inner plate materials was measured using a surface roughness measuring device.

For the outer plate material, AlB and C shown in Figure 1 are used.
Measurements were taken at three locations, and the respective measurement results are shown in Figures 4 to 6.
As shown in the figure. As shown in FIGS. 4 to 6, the area A is about 13 μm, the area B is about 17 μm, and the area C is about 17 μm.
It was 5 μm.

In addition, the inner plate material is shown in Fig. 2,
Measurements were taken at two locations E, and the respective measurement results are shown in FIGS. 7 and 8. As shown in FIGS. 7 and 8, it was approximately 7 μm at the D location and approximately 6 μm at the SE location.

Then, these outer and inner plate materials were subjected to chemical polishing treatment in the same manner as in the above example, and the height of the polish at each location was measured every 80 seconds. As a result, the 9th
As shown in Figures to Figure 11, the outer plate material is made of 60
After 90 seconds had elapsed, there was no more flash at location A, and after 90 seconds, there were no more flashes at locations B and C. In addition, the inner plate material is 30s as shown in FIGS. 12 and 13.
After elapse of ec, the paris at the E point disappeared, and after eosec elapsed, the paris at the point after eosec disappeared.

As a result of the above, the outer plate material underwent chemical polishing treatment at 90%
It was found that if the inner plate material was treated for 60 seconds, the particles at each location could be completely removed.

(2) Change in surface roughness Changes in surface roughness of the outer and inner plate materials due to chemical polishing treatment were measured using a surface roughness measuring device every 80 seconds. As a result, as shown in Figure 14,
The surface roughness, which was 5 to 7 μRz at the initial stage, decreased to 2 to 8 μR2 or less after 60 seconds, indicating that the surface roughness could be sufficiently fine.

(3) Change in surface shape Changes in the surface shape of the outer and inner plate materials due to chemical polishing treatment were measured using a surface roughness measuring device. Measurements were performed every 30 seconds from the initial stage to 150 seconds, and the results are shown in FIG. As is clear from FIG. 15, the sharp irregularities that existed at the beginning gradually decreased as the processing time progressed, and it can be seen that the surfaces of the outer and inner plate materials were smoothed.

(Test 2) A differential durability test was conducted by assembling the outer and inner plates produced in the above example and the conventional outer and inner plates that were not subjected to chemical polishing treatment into a viscous coupling. compared with the product. The operating conditions of the viscous coupling in this differential durability test were a single shaft rotating differential, a low differential rotation speed at a predetermined speed, and silicone oil with a viscosity of 5.00 cSt was used as the viscous fluid. Note that the test conditions were the same except for the difference in the outer and inner plates between the inventive product and the conventional product. The results are shown in FIG.

As shown in Figure 16, in the case of the conventional product, the durability target was 1.
．． The transmitted torque, which had been at a constant value after 1 time, suddenly increased, but in the case of the product of the present invention,
Even after twice the durability target time had elapsed, the transmitted torque remained almost constant without any sudden increase. This revealed that the product of the present invention can significantly improve the durability of viscous couplings.

After the differential durability test, the amount of wear on the outer and inch plates was examined, and the amount of wear on the product of the present invention was about half that of the conventional product.

In addition, when we examined the silicone oil after the differential durability test, we found that in the case of conventional products, there was a large amount of foreign matter such as abrasion particles mixed in, and the viscosity had increased to an unmeasurable state. With the product of the present invention, there is no increase in viscosity;
There was also very little contamination of foreign matter such as wear particles.

[Effects of the Invention] According to the thrust plate manufacturing method of the present invention, after the punching process is completed, the surface treatment process is performed through the chemical polishing process of polishing the surface of the thrust plate material, so that the wear resistance of the manufactured thrust plate is improved. Since the properties are further improved, gelation of silicone oil can be prevented and the durability of the viscous coupling can be improved.

[Brief explanation of drawings]

Figures 1 to 3 relate to embodiments of the present invention; Figure 1 is a front view of an outer plate material, Figure 2 is a front view of an inch plate material, and Figure 3 is a process diagram of a chemical polishing process. . Figure 4~
FIG. 6 is a graph showing the measurement results of Paris at each location of the outer plate material, and FIGS. 7 and 8 are graphs showing the measurement results of Paris at each location of the inner plate material. Figures 9 to 11 show the relationship between the height of the polish at each location of the outer plate material and the chemical polishing treatment time. It is a graph showing the relationship with polishing processing time. 14th rj! J is a graph showing the relationship between the surface roughness of the outer and inner plate materials and the chemical polishing treatment time; and No. 15 is a graph showing the change in the surface shape of the outer and inner plate materials in the chemical polishing treatment. FIG. 16 is a characteristic diagram showing the relationship between transmitted torque and time in a differential durability test. FIG. 17 is a sectional view of the viscous coupling. Engineering: Outer plate material (thrust plate material) 2.
...Inner plate material (thrust plate material) Patent applicant Hiroshi Okawa, Toyota Motor Corporation agent, patent attorney Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 During chemical polishing Fji (sec) During chemical polishing Open (sec) Figure 12 N5 during chemical polishing (SeC) M during chemical polishing (SeC) M during chemical polishing (sec) Figure 15

Claims (1)

[Claims] (1) A viscous coupling consisting of a punching process in which a low carbon steel plate is press punched to form a thrust plate material of a predetermined shape, and a surface treatment process in which a soft nitrided layer and an oxidized layer are sequentially formed on the surface of the thrust plate material. A method for manufacturing a thrust plate for a viscous coupling, wherein after the punching step, the surface treatment step is performed through a chemical polishing step of polishing the surface of the thrust plate material.