JPH10196809A - Manufacture of cylindrical sliding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the dimensional accuracy of products by setting the temperature of an inner mold lower than that of the outer mold within a specific temperature range at the time of injection, when a cylindrical sliding member is manufactured by injecting polyphenylene sulfide resin. with carbon fiber added into a cavity between the inner and outer mold. SOLUTION: A cylindrical sliding member 1 used as a spool valve body for a control valve of the hydraulic controlling device for the automatic transmission of vehicles is formed by injection molding in a cylindrical shape with a bottom being closed at one end thereof and is provided with an annular recessed section 2 on the periphery at the middle along the axial direction thereof. Though the cylindrical sliding member is manufactured by injecting polyphenylene resins added with carbon fiber into a cavity between an inner and outer mold, the temperature of the inner mold is set lower within a rang of 10-40 deg.C than that of the outer mold at the time of injection. Consequently, the heat radiating volume to both the outer and inner mold are equalized; which results in keeping both the difference in the shrinking speed and the strain between the inner and outer surface of the sleeve shape sliding member 1 and improving the dimensional accuracy of the injection molding products.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of a cylindrical sliding member for obtaining a cylindrical sliding member such as a spool valve by injecting a polyphenylene sulfide resin containing carbon fibers between an inner mold and an outer mold. About the method.

[0002]

2. Description of the Related Art A sliding member made of polyphenylene sulfide resin to which carbon fiber is added is known, for example, from Japanese Patent No. 25500888.

[0003]

By the way, at the time of injection molding of such a cylindrical sliding member, the temperature of the polyphenylene sulfide resin to which carbon fiber is added is 300-400.
The mold temperature is set to about 320 ° C. and the mold temperature is set to about 120 to 170 ° C. Generally, the inner mold temperature and the outer mold temperature are set to be the same. However, the area of resin contact with the inner mold is smaller than the area of resin contact with the outer mold, and thus the amount of heat radiation of the resin to the inner mold is smaller than the amount of heat radiation to the outer mold. Among them, the distortion due to the difference in the contraction speed of the outer surface is caused, and the molding dimensional accuracy of the cylindrical sliding member is inevitably reduced, so that post-processing is required.

The present invention has been made in view of such circumstances, and has as its object to provide a method of manufacturing a cylindrical sliding member capable of improving molding dimensional accuracy to the extent that post-processing is not required. And

[0005]

In order to achieve the above object, the present invention relates to a method for forming a cylindrical sliding member by injecting a polyphenylene sulfide resin containing carbon fibers between an inner mold and an outer mold. In the method for manufacturing a sliding member,
The temperature of the inner mold is set to be lower than the temperature of the outer mold in the range of 10 to 40 ° C. at the time of injection.

[0006] By setting the temperature of the inner mold to be lower than the temperature of the outer mold, it is possible to compensate for the fact that the resin contact area with the inner mold is smaller than the resin contact area with the outer mold. By increasing the amount of heat and setting the temperature difference to 10 to 40 ° C, the amount of heat radiated to the outer and inner dies is made uniform, and the difference in the shrinkage speed of the outer surface of the cylindrical sliding member when molding is completed is minimized. It is possible to improve the molding dimensional accuracy by keeping the distortion small and keeping the distortion small.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a cylindrical sliding member 1 used as a spool valve of a control valve for a hydraulic control device of an automatic transmission for a vehicle has a bottomed cylindrical shape whose one end is closed by injection molding. An annular recess 2 is provided on the outer periphery of the intermediate portion along the axial direction. The cylindrical sliding member 1 is slidably fitted to a casing made of, for example, an aluminum alloy so as to exhibit a pressure adjusting or hydraulic switching function.

The material constituting the tubular sliding member 1 for controlling the hydraulic pressure of the automatic transmission for a vehicle is such that the amount of hydraulic oil leaking between the casing and the casing in a high-temperature region can be reduced, and good sliding can be achieved. Excellent responsiveness and abrasion resistance due to dynamic characteristics, wear particles do not adversely affect other components even when worn, little change over time in high-temperature hydraulic oil, and light weight It is necessary to provide a material having such characteristics. For a material having such characteristics, a polyphenylene sulfide resin (hereinafter, referred to as a PPS resin) of 50 to 90% by weight may be used.
A resin composition to which carbon fiber is added by weight% can be suitably used.

[0009] PPS resins can be broadly classified into two types: a crosslinked type in which the molecular weight is increased by heat treatment in air after the synthesis reaction, and a linear type, which has been synthesized in advance to a high molecular weight. Thus, both types of PPS resins are excellent in heat resistance and chemical resistance, and can be widely used for OA equipment, home electric appliances and automobile parts. However, as shown in FIG. PP
The S resin has a large swelling amount in a high-temperature hydraulic oil, whereas the cross-linked PPS resin has a small amount of dimensional change with time, and operates between the casing and the casing in a high-temperature region. As a PPS resin used as a constituent material of the cylindrical sliding member 1 which needs to maintain an appropriate clearance between the casing and the casing so as to reduce the amount of oil leakage and enable smooth sliding, a cross-linked PPS resin is used. It is necessary to use a resin.

As a reinforcing material for an injection molded product, carbon fiber or glass fiber is generally used. However, by adding carbon fiber to a crosslinked type PPS resin, injection molding is performed rather than adding glass fiber. It is possible to make the dimensional accuracy of the molded product relatively high. This is because the resin composition containing carbon fibers has a higher thermal conductivity than the resin composition containing glass fibers, so that the resin composition, which greatly affects the dimensional accuracy of the injection molded product, is greatly reduced. It can be guessed that the cooling proceeds more uniformly.

The use of carbon fiber as the reinforcing material can increase the coefficient of thermal expansion. The tubular sliding member 1 made of a resin composition obtained by adding carbon fiber to a crosslinked PPS resin can be used. The amount of hydraulic oil leaked from the gap between the casings can be made relatively small. Here, in a casing made of aluminum alloy, case hardening steel (JIS SCM420) is carburized and quenched, and then polished and finished. A cylindrical sliding member made of an aluminum alloy which is polished and finished after being subjected to a treatment, and a cylindrical sliding member formed by injection molding of a resin composition obtained by adding 30% by weight of carbon fiber to a crosslinked PPS resin. Experiments on the leakage of hydraulic oil by the three members of the moving member 1 resulted in the results shown in FIG. 3, and the cylindrical sliding member 1 was formed by injection molding of a resin composition obtained by adding carbon fiber to a crosslinked PPS resin. Leakage is smaller than that of iron and animinium alloys, and the viscosity of hydraulic oil is low, especially at high temperatures. Accordingly, while the leakage amount of iron and an aninium alloy alloy increases, the leakage amount of the tubular sliding member 1 made of a resin composition obtained by adding carbon fiber to a cross-linked PPS resin can be suppressed to a relatively small amount. Is evident.

[0012] Even if the carbon fiber is worn by the operation for a long time and the wear powder is mixed into the working oil, the wear powder hardly damages other components.
Moreover, since the specific gravity is lower than that of the glass fiber, the weight of the tubular sliding member 1 can be reduced.

This carbon fiber can be used effectively regardless of the fiber diameter and the manufacturing method.
The amount added to the resin is preferably limited to 10 to 50% by weight based on the entire resin composition comprising the PPS resin and the carbon fibers. That is, the addition amount is 10% by weight.
In the following cases, it is difficult to obtain a high-precision molded product at the time of injection molding, and slidability and strength are also insufficient. When the amount is 50% or more, the injection moldability is extremely reduced. Moreover, if the injection pressure or injection speed is increased to supplement the injection moldability, burrs or the like may occur during injection molding,
Not only post-processing is required, but also the life of the mold is shortened, and a large amount of expensive carbon fiber is added, resulting in an increase in manufacturing cost.

By setting the addition amount of the carbon fiber to 10 to 50% by weight, the PPS resin becomes 50 to 90% by weight, but does not impair the characteristics required for the cylindrical sliding member 1 for an automatic transmission. In the range, an inorganic filler or an organic filler may be blended.

When the cylindrical sliding member 1 is injection-molded, for example, a mold device as shown in FIG. 4 is used. This mold device corresponds to the shape of the cylindrical sliding member 1. An outer mold 10 and an inner mold 11 that form a cavity 13 therebetween are provided. The outer mold 10 has a fixed mold 4 corresponding to the outer surface of one end closing portion of the cylindrical sliding member 1 and having a gate 3, and a fixed mold 5 corresponding to the outer periphery of one end of the cylindrical sliding member 1. In order to form a fixed mold 7 corresponding to the outer periphery on the other end side of the cylindrical sliding member 1 and an annular concave portion 2 (see FIG. 1) in the axially intermediate portion of the cylindrical sliding member 1 in cooperation with each other. A pair of movable dies 6a and 6b movable between the fixed dies 5 and 7
A fixed mold 8 which contacts the fixed mold 7 on the opposite side of the movable molds 6a and 6b, and a movable movable in the axial direction which is formed in a cylindrical shape corresponding to the outer surface of the other end of the cylindrical sliding member 1. And a mold 9. The inner mold 11 is formed in a pin shape corresponding to the inner surface shape of the cylindrical sliding member 1 and is movable in the axial direction. Is built in.

Using such a mold apparatus, 50 to 90
In performing injection molding of a resin composition obtained by adding 10 to 50% by weight of carbon fiber to 10% by weight of PPS resin, there is no particular limitation. For example, the PPS resin and carbon fiber are kneaded by a twin-screw kneader or the like. The resin composition obtained by melting and cutting into a pellet is obtained at a temperature of 300 to 320 ° C. and an injection pressure of 300 to 1000 kg /
Inject into the cavity 13 from the gate 3 in cm ² . At this time, the melt viscosity of the PPS resin to which 10 to 50% by weight of the carbon fiber is added is not particularly limited as long as it is within the range of the melt viscosity at which injection molding is possible.

The injection molding machine may be an electric servomotor driven molding machine or a hydraulic molding machine with an accumulator function, having a closed control function capable of repeatedly feeding back certain molding conditions and positively providing feedback. Desirably, the presence or absence of vacuum evacuation of the cavity 13 is not particularly limited, but evacuation is effective for improving the appearance of a molded product.

By the way, depending on the temperature of the outer mold 10 and the temperature of the inner mold 11 during injection molding, distortion occurs due to the difference in the contraction speed of the outer surface of the cylindrical sliding member 1 upon completion of molding, and the cylindrical sliding member 1 is distorted. In order to improve the molding dimensional accuracy to such an extent that the post-processing is not required, the range of the temperature difference between the outer die 10 and the inner die 11 is determined. , Cylinder temperature 300 ~ 3
20 ° C., the injection speed is 20-40 mm / sec,
When the pressure is 300 to 1000 kg / cm ² and the temperature of the outer mold 10 is kept constant at, for example, 170 ° C., the temperature of the inner mold 11, that is, the temperature difference between the outer mold 10 and the inner mold 11 is changed to change the cylindrical sliding member. The outer diameter of the cylindrical sliding member 1 is set at four locations A, C, D, and F spaced apart in the axial direction of the cylindrical sliding member 1 (see FIG. 1).
Was measured respectively.

At this time, condition 1 in which the temperature of the inner mold 11 was 125 ° C. (that is, the temperature difference ΔT from the outer mold 10 was 45 ° C.)
When the temperature of the inner mold 11 is 145 ° C. (that is, the temperature difference ΔT =
25), and the temperature of the inner mold 11 was set to 16
Under three conditions of condition 3 at 5 ° C. (that is, the temperature difference ΔT = 5 ° C.), the outer diameter of each of the three cylindrical sliding members 1 was measured.
6, the result shown in FIG. 6 was obtained under the condition 2, and the result shown in FIG. 7 was obtained under the condition 3.

Each measurement point A, C, D,
In F, the outer diameter is measured in the X-axis direction which is a direction along one diameter line of the cylindrical sliding member 1 and in the Y-axis direction orthogonal to the X-axis direction, respectively. 1X,
1Y indicates the outer diameter of the first cylindrical sliding member 1 in the X-axis and Y-axis directions, 2X and 2Y indicate the outer diameter of the second cylindrical sliding member 1 in the X-axis and Y-axis directions, 3X and 3Y indicate the outer diameters of the third cylindrical sliding member 1 in the X-axis and Y-axis directions.

The difference between the maximum and minimum dimensions of the outer diameter of the cylindrical sliding member 1 obtained by changing the temperature difference ΔT between the outer die 10 and the inner die 11 as described above, ie, the maximum dimensional difference, is as follows.
As shown in FIG. This maximum dimensional difference is caused by distortion during injection molding, and a small maximum dimensional difference means excellent molding dimensional accuracy. Thus, as the molding dimensional accuracy to the extent that post-processing is not required after injection molding, the maximum dimensional difference needs to be 20 μm or less.
It is clear from FIG. 8 that the temperature difference ΔT of the inner mold 11 may be set to 10 to 40 ° C.

That is, by setting the temperature of the inner mold 11 to be lower than the temperature of the outer mold 10, it is possible to compensate for the fact that the resin contact area with the inner mold 11 is smaller than the resin contact area with the outer mold 10. The amount of heat radiated from the resin can be increased, and the amount of heat radiated to the outer mold 10 and the inner mold 11 can be made uniform by setting the temperature difference to 10 to 40 ° C., so that the cylindrical sliding at the time of completion of molding is performed. The difference in shrinkage speed between the outer surfaces of the members 1 can be suppressed as small as possible, the amount of distortion can be suppressed, and the molding dimensional accuracy can be improved.

Therefore, in the mold apparatus shown in FIG. 4, the outer mold 10 is heated by a heating means (not shown) so that the temperature of the outer mold 10 becomes constant at, for example, 170.degree. The temperature is adjusted by the heat pipe 12 so that ΔT is 10 to 40 ° C.

Next, Examples 1 to 1 actually obtained by injection molding were used.
Table 1 shows the results of measurement of specific gravity, outer diameter, roundness and concentricity, and swelling test for the cylindrical sliding members 1 of Comparative Examples 1 to 3 and Comparative Examples 1 to 3. Become.

[0025]

[Table 1]

The raw materials used in each of the above Examples and Comparative Examples are as follows. Crosslinked PPS resin; Toray Co., grade name M-
1900 Linear type PPS resin; manufactured by Toray Industries, grade name M
-2588 carbon fiber; made by Kureha Chemical Co., grade name M-1
02T glass fiber; grade name 03MA497, manufactured by Asahi Fiber Glass Co., Ltd. The evaluation of the molded product was based on the following method. Specific gravity: Measured according to JIS K6911 (underwater displacement method). Evaluation of outer diameter dimensional accuracy: The outer diameter at one axial position of the cylindrical sliding member 1 having an outer diameter of 12 mm shown in FIG. 1 was measured using a micrometer (measurement accuracy 1 μm) manufactured by Mitutoyo Corporation. The difference between the expected finished dimension set in consideration of the shrinkage ratio of the molding material and the measured dimension based on the cavity dimension of the mold apparatus shown in FIG. The sample was marked with Δ, and the sample with 30 μm or more was marked with ×. Evaluation of roundness: Measured using a roundness measuring device manufactured by Tokyo Seimitsu Co., Ltd. (measurement accuracy: 0.1 μm). When the roundness of the cavity is 1 μm or less, the roundness of the molded product is 10 μm or less.表 記, 10１０〜30 μm and △, and 30 μm and more ×. Evaluation of coaxiality: Measured using a Tokyo Seimitsu Co. three-dimensional measuring device (measurement accuracy: 1 μm).
Those having a thickness of 10 to 30 μm were denoted by Δ, and those having a diameter of 30 μm or more were denoted by X. Swelling test; immersed in oil for automotive automatic transmission (Honda genuine ATF oil) at 130 ° C for 1000 hours,
A sample having a dimensional change of 2 μm or less was indicated by ○, a sample having a dimensional change of 2 to 5 μm was indicated by Δ, and a sample having a dimension change of 5 μm or more was indicated by X.

Further, at the time of injection molding, the parts by weight of each of Examples and Comparative Examples shown in Table 1 were heated at 320 ° C.
Was melt-kneaded with a co-axial twin-screw kneader set to obtain pellets for molding. The pellets were dried at 140 ° C. for 4 hours, and the injection molding machine was set at a cylinder temperature of 330 ° C. (manufactured by FANUC, 30A, electric servo motor drive type).
The pellets after drying were injected at a cylinder speed of 90 mm / sec from a pin gate having a diameter of 1 mm with the outer mold temperature set at 150 ° C. and the inner mold temperature set at 120 ° C. (temperature difference 30 ° C.). .

As apparent from Table 1 above, 10 to 50
Injection molding of a resin composition obtained by adding a weight percent of carbon fiber to a crosslinked PPS resin with the temperature difference between the outer mold 10 and the inner mold 11 in the range of 10 to 40 ° C. It is possible to obtain the cylindrical sliding member 1 having a high degree of accuracy of a circularity and a coaxiality of 10 μm or less.
In addition, the one using linear type PPS resin has a large swelling, and the one using glass fiber as a fiber reinforcing material has poor dimensional accuracy.
It is not suitable as the cylindrical sliding member 1.

FIG. 9 shows the results of experiments on wear resistance and dynamic friction coefficient in order to confirm the suitability of the cylindrical sliding member 1. In this experiment, a comparative test piece obtained by subjecting an aluminum alloy (JIS A6061) to hard alumite treatment and a cross-linked PPS resin by 30% were used.
And a test piece of a resin molded product filled with a carbon fiber of 10% by weight, the chip side was used as the two test pieces, and an aluminum die-cast alloy (J
The oil for automatic transmission (Honda genuine ATF oil) was dropped using IS ADC12).

As is clear from FIG. 9, the comparative test piece has a higher dynamic friction coefficient than the test piece made of the resin composition, and when the surface pressure is slightly increased, seizure occurs and the amount of wear is large. Become. On the other hand, the test piece of the resin composition had a low dynamic friction coefficient and a low wear amount, and the disk-side wear amount was too small to be measured.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

For example, the present invention is applicable not only to a cylindrical sliding member 1 used in a hydraulic control device of an automatic transmission for a vehicle, but also to a cylindrical sliding member formed by injection molding of a resin composition made of a PPS resin to which carbon fiber is added. It is widely applicable to members. In addition, in order to provide the characteristics necessary for the cylindrical sliding member 1, the description has been given by limiting to the cross-linking type PPS resin.
As long as swelling does not pose a problem, the PPS resin may be of a linear type.

[0033]

As described above, according to the present invention, the temperature of the inner mold is set lower than the temperature of the outer mold to increase the amount of heat radiated from the resin to the inner mold, and the temperature difference is reduced to 10 to 40 ° C. By setting to, the amount of heat radiation to the outer mold and the inner mold is equalized, and the difference in the shrinkage speed of the outer surface of the cylindrical sliding member when molding is completed is minimized, and the amount of distortion is minimized to minimize molding dimensional accuracy Can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a cylindrical sliding member.

FIG. 2 is a graph showing the results of a swelling test.

FIG. 3 is a graph showing a result of a hydraulic oil leakage test.

FIG. 4 is a longitudinal sectional view of a mold apparatus.

FIG. 5 is a graph showing an outer diameter measurement result under condition 1.

FIG. 6 is a graph showing an outer diameter measurement result under a condition 2;

FIG. 7 is a graph showing an outer diameter measurement result under condition 3;

FIG. 8 is a graph showing a maximum dimensional difference due to a temperature difference.

FIG. 9 is a graph showing a change in a dynamic friction coefficient due to a surface pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylindrical sliding member 10 ... Outer type 11 ... Inner type

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 81:00 105: 12 B29L 23:00 (72) Inventor Masahiro Akioka 1-4-1 Chuo, Wako-shi, Saitama Inside Honda R & D Co., Ltd. In company

Claims (1)

[Claims] An inner mold (11) and an outer mold (1) are made of a polyphenylene sulfide resin to which carbon fibers are added.
0) In the method of manufacturing a cylindrical sliding member to obtain the cylindrical sliding member (1) by injection during the injection, the temperature of the inner mold (11) is set to be 10 to 40 ° C. lower than the temperature of the outer mold (10) at the time of injection. A method for manufacturing a cylindrical sliding member, wherein the setting is made lower in the range of: