JPH08210541A - Valve body and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a valve body and a manufacturing method for it in which dimensional precision for land groove width or land groove interval is high and no machining for these is required. CONSTITUTION: In a manufacturing method for a valve body constituting a hydraulic control valve, green compact bodies 4, 5 divided by a face including a center line of a spool hole 1 are molded, and then, the division faces of the green compact bodies 4, 5 are mutually butted so as to be sintered. The valve body produced by this manufacturing method is formed by sintering a green compact body in which Fe containing 0.3-1.5% by weight of C and 0.3-1.5% by weight of P is used as a principal constituent and the composition is controlled so as to be provided with a relative density of 95% or more after sintering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve body that constitutes a hydraulic control valve and a method for manufacturing the same, and in particular, it requires a complicated shape and high accuracy provided in a hydraulic circuit for controlling a hydraulic actuator. And a manufacturing method thereof.

[0002]

2. Description of the Related Art Among various control valves provided in a hydraulic circuit for controlling a hydraulic actuator, in particular, a valve body of a directional control valve for controlling a flow direction and a flow rate of pressure oil to the hydraulic actuator is a land type. Since the groove, the pressure oil passage, etc. have a complicated shape, a valve body material made of cast iron, which is conventionally produced by a casting method with a core, is machined and used.

[0003]

When a valve body is manufactured by a casting method, a spool core, a land groove, a pressure oil passage, etc. are made of a sand-based core, and the core is incorporated into a mold. Although the valve body is cast with, the dimensional accuracy of the valve body material is not always good due to the assembling accuracy of the core and the lifting of the core during pouring. On the other hand, in order to perform precise hydraulic control, it is particularly necessary to make the land groove width and land groove interval highly precise. Therefore, in addition to the hole in which the spool slides, the pipe connection surface, etc., the side surface of the land groove Is also cut or ground to obtain a desired dimensional accuracy. Therefore, there is a problem that the machined portion of the cast valve body is increased and the manufacturing cost of the valve body is increased. The present invention focuses on the above-mentioned conventional problems, and an object of the present invention is to provide a valve body having a high dimensional accuracy of the width of the land groove and the land groove interval, and which does not require machining, and a manufacturing method thereof.

[0004]

In order to achieve the above object, a method of manufacturing a valve body according to a first aspect of the present invention is a method of manufacturing a valve body that constitutes a hydraulic control valve, including a center line of a spool hole 1. Powder compacts 4, 5 divided by surface
After molding, the powder compacts 4 and 5 are characterized in that the divided surfaces thereof are matched with each other and sintered. A method of manufacturing a valve body according to a second aspect of the present invention is the method of manufacturing a valve body according to the first aspect of the present invention, in which a steel pipe 6 having land grooves
Is incorporated into the spool holes of the divided powder compacts 9 and 10 and sintered. A method of manufacturing a valve body according to a third aspect of the present invention is the method of manufacturing a valve body according to the first aspect of the present invention, in which steel pipes 11 are arranged at respective land portions of spool holes of the divided powder compacts 9 and 10. It is characterized in that the synthetic resin 12 is incorporated into each land groove and sintered. In the method for manufacturing a valve body according to the fourth aspect of the present invention, the powder compact 15 is divided by a plane including the center line of the spool hole 1,
After compacting 16, the powder compacts 15 and 16 are individually sintered, and copper is infiltrated by matching the divided surfaces of the sintered compacts 15 and 16. In the valve body according to the fifth aspect of the present invention, the powder compact of the valve body produced by the method for producing a valve body according to the first to third aspects is C; 0.3 to 1.5 wt%, P; 0.
Fe containing 3 to 1.5 wt% is a basic component, and the relative density after sintering is adjusted to 95% or more.

[0005]

According to the first aspect of the present invention, when a valve body having a complicated shape is divided by a surface including the center line of the spool hole, each of which is powder compacted and then the divided surfaces are sintered together, the sintering is performed. At the same time, the divided surfaces are firmly joined by diffusion joining, and the dimensional accuracy of each land groove arranged in the spool hole can be significantly improved as compared with the conventional casting method. According to the second aspect of the present invention, if the steel pipe in which the land groove is machined in advance is disposed in the valve body and is sintered, the steel pipe is firmly joined to the valve body at the time of sintering and is machined into the steel pipe. The dimensional accuracy of each land groove is further improved than the dimensional accuracy of each land groove due to the sintering of the powder compact. According to the third invention, if the steel pipe is disposed in the land portion of the valve body and the synthetic resin pipe is disposed in the land groove portion in advance and the sintering is performed, the synthetic resin pipe is not melted during the sintering and the steel pipe is firmly attached to the valve body. Since it is joined to, the dimensional accuracy of each land groove can be improved. According to the fourth aspect of the invention, after the powder compact is sintered alone, the divided surfaces are joined together and Cu infiltration is performed, so that the divided surfaces are firmly joined and the dimensional accuracy of each land groove is improved. Can be made.

According to a fifth invention, in any one of the first to third inventions, the powder compact is C: 0.3-1.
5 wt%, P; Fe containing 0.3 to 1.5 wt% as a basic component and adjusted to a component such that the relative density after sintering becomes 95% or more, so ensure sufficient pressure resistance. Is.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a valve body according to the present invention will be described below in detail with reference to the drawings. 1 is a sectional view of an embodiment of a valve body manufactured by the method for manufacturing a valve body according to claim 1, and FIG. 2 is a front view of the same. Powder, for example Fe-0.8C-
The 1.2P material has a sinter-bonding property and its components are adjusted so that it can be sintered at a high density. The die used for compacting the powder has a shape that is divided into two parts on a plane including the center line of the spool hole 1 of the valve body, and the land groove 2
The pressure oil passage 3 and the pressure oil passage 3 subsequent thereto can be formed by transfer molding. The mold has a size that allows for the contraction of the powder compact by sintering. The divided surfaces of the powder compacts 4 and 5 formed by using this mold are closely adhered to each other without any deviation so that the divided surfaces are completely joined.

As an experimental example, commercially available atomized iron powder and iron phosphate (325 mesh or less) and Lonza graphite (KS
6), Fe-1.2 wt% C-0.8 wt% P
0.5% accra wax was added to the mixed powder described above as a lubricant and mixed sufficiently uniformly, and the powder compacts 4 and 5 shown in FIG. 1 were manufactured using the above-mentioned mold. The molding pressure at this time was 3.5 ton / cm ² . The divided surfaces of the powder compacts 4 and 5 are closely attached to each other without any deviation,
Vacuum sintering was performed at 50 ° C. for 1 hour. As a result, the green compacts 4 and 5 were firmly bonded to each other, and the sintered density became 7.6 (97% in relative density). The dimensional accuracy of the land groove spacing of the valve body thus manufactured was ± 0.2 mm, which was less than 1/2 of the tolerance ± 0.5 mm. 420 kg /
In the hydraulic test up to cm ^2, no oil leakage was found from various parts of the valve body, and very good results were obtained.

FIG. 3 is a sectional view of an embodiment of a valve body manufactured by the method for manufacturing a valve body according to the second aspect. In the die, a portion corresponding to the spool hole is made large by the thickness of the steel pipe 6 and a gap for applying an appropriate caulking force to the steel pipe 6 during contraction due to sintering. The components of the powder, the sintering conditions, etc. are the same as those of the valve body of the first aspect. The inner diameter of the steel pipe 6 is a dimension in which a finishing allowance is left in the spool hole, and a land groove 7 is provided at a predetermined position on the inner peripheral surface as shown in FIG.
An oil hole 8 communicating with the pressure oil passage of the valve body extends from the outer peripheral surface of the steel pipe 6. When the divided surfaces of the powder compacts 9 and 10 are brought into close contact with each other, the steel pipe 6 is arranged in a portion corresponding to the spool hole of the powder compacts 9 and 10, and the divided surface of the powder compacts 9 and 10 is sintered. The contact surfaces of the green compacts 9 and 10 and the steel pipe 6 are joined together.

FIG. 5 is a sectional view of an embodiment of a valve body manufactured by the method for manufacturing a valve body according to claim 3. The components of the powder and the shape of the mold are the same as those of the valve body according to the second aspect. A steel pipe 11 matching the length of each land portion of the valve body and a synthetic resin 12 matching the width of the land groove portion are alternately arranged, and a core member 13 is inserted into each inner periphery to manufacture an assembly product. To do. When the divided surfaces of the powder compacts 9 and 10 are brought into close contact with each other, the assembly is fixed to the portions of the powder compacts 9 and 10 corresponding to the spool holes. The powder compact of the valve body thus assembled is heated and vacuum-sintered after the synthetic resin is melted and removed.

As an example of the above experiment, the inner diameter is 11.9 mm.
And the low carbon steel pipe 11 (C; 0.15%) whose length matches the length of each land, and the inner diameter is 11.9 mm.
Then, a core material 13 made of a paper tube having an outer diameter of 11.9 mm and an acrylic resin tube 12 in which the length of the tube is adjusted to the width of each land groove portion
Alternately, the positioning tubes 14 made of acrylic resin were inserted at both ends, and were installed at predetermined positions in the portions corresponding to the spool holes of the powder compacts 9 and 10. 600 ° C
Heat for 2 hours in the acrylic resin tube 12 and positioning tube 14
After removing and, remove the core material 13 and
Vacuum sintered for hours. There was no unwelded portion on the joint surface between the steel pipe 11 and the sintered body, and the joint state was good. The dimensional accuracy of the land groove spacing is ± 0.2 mm for a tolerance of 0.5 mm,
The maximum vacuum degree of the inner diameter of the steel pipe 11 is 0.1 mm, and there is no problem in working.

FIG. 7 is a front view showing an embodiment of the valve body according to the present invention. Reduced iron powder as powder for molding,
Graphite and copper powder are mixed and the composition is adjusted so that the powder can be sintered at high density. The powder is compacted by the mold used in the embodiment of claim 1, and then individually sintered. These sintered bodies 1
The divided surfaces 5 and 16 are joined together, and the Cu-based infiltration material 17 is placed on the upper surface of the sintered body 15 and heated to join the divided surfaces.

As an experimental example, commercially available reduced iron powder (Kawatetsu KI
P255M), Lonza graphite (KS6) and Cu powder (200 mesh or less), and 0.8% zinc stearate is added to the mixed powder to obtain a sufficiently uniform mixture.
Using the same mold as in the above example, powder compacting was performed at a molding pressure of 6 ton / cm ² . This powder compact was made into 11 using an AX furnace.
After sintering so that the relative density becomes 85 to 90% at 50 ° C., the divided surfaces of the sintered bodies 15 and 16 are brought into close contact with each other, and the Cu-based infiltrant 17 is placed on the upper surface and melted at 1100 ° C. Immersion joining was performed. The sintered bodies 15 and 16 were firmly bonded to each other, and the sintered density was 7.4 (95% in relative density). The tolerance of the land groove spacing of the valve body manufactured in this way is ±
It satisfies 0.5 mm, and no oil leakage from various parts of the valve body was found in the hydraulic test up to 420 kg / cm ² .
Very good results have been obtained.

[0014]

As described above, according to the present invention, a valve body having a complicated shape is divided by a surface including the center line of the spool hole, and is pressed and molded by using a die, or a land is formed. Steel pipes with machined grooves, steel pipes in the land part, and synthetic resin pipes arranged so that the land groove part is located in the land material and inserted into the core material are combined with the above-mentioned powder compact, and the divided surface is obtained by sintering. Therefore, the dimensional accuracy of each land groove arranged in the spool hole can be significantly and easily improved as compared with the conventional casting method.

In addition to the above, the dimensional accuracy of each land groove is also improved when the divided surfaces are joined by Cu infiltration after sintering the powder compact by itself. Therefore, in the valve body manufactured in this manner, the flow rate of the pressure oil can be precisely controlled, and since it is not necessary to machine each land groove portion, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of a valve body manufactured by the method for manufacturing a valve body according to claim 1.

FIG. 2 is a front view of FIG.

FIG. 3 is a cross-sectional view of an embodiment of a valve body manufactured by the method for manufacturing a valve body according to claim 2.

FIG. 4 is a sectional view of a steel pipe.

FIG. 5 is a sectional view of an embodiment of a valve body manufactured by the method for manufacturing a valve body according to claim 3;

FIG. 6 is a front view showing an embodiment of the valve body according to claim 5;

[Explanation of symbols]

 1 Spool hole 4,5,9,10 Powder compact 6,11 Steel pipe 12 Synthetic resin pipe 15,16 Sintered body

Claims (5)

[Claims] 1. A method for manufacturing a valve body constituting a hydraulic control valve, wherein the powder compacts 4, 5 are formed by dividing the surface of the spool hole 1 including the center line, and then the powder compacts 4, 5. 5. A method for manufacturing a valve body, characterized in that the divided surfaces are mutually sintered together. 2. The method for manufacturing a valve body according to claim 1, wherein the steel pipe 6 having a land groove formed therein is incorporated into the spool holes of the divided powder compacts 9 and 10 and sintered. 3. The steel pipe 11 is disposed in each land portion of the spool holes of the divided powder compacts 9, 10 and the synthetic resin 12 is incorporated in each land groove portion and sintered. A method for manufacturing the described valve body. 4. The powder compacts 15, 16 are molded by being divided along a plane including the center line of the spool hole 1, and then the powder compacts 15, 16 are respectively sintered alone, and these are sintered. Body 1
5. A method for manufacturing a valve body, which comprises infiltrating copper so that divided surfaces 5 and 16 are aligned with each other. 5. The valve body manufactured by the method for manufacturing a valve body according to claim 1, claim 2, or claim 3, wherein the powder compact is C: 0.3 to 1.5 wt.
%, P; Fe containing 0.3 to 1.5 wt% as a basic component, and adjusted to a component such that the relative density after sintering is 95% or more.