JPH1061768A - Aluminum alloy-made cylinder body and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy-made cylinder body and a method of manufacture thereof lightening weight also improving pressure resistance strength. SOLUTION: In a cylinder body 1, one end part has a closed cylindrical shape, in its peripheral surface, a plurality of rib-shaped protruded parts 8 extended in a circumferential direction is formed. This cylinder body 1, using a casting mold provided with a rib-shaped recessed part, is manufactured by casting. Then, by a synergetic effect of a mechanical reinforcing effect by the rib-shaped protruded part 8 and a strength improving effect by fining of a composition, the cylinder body 1 excellent in pressure proof strength light in weight can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder body of a drive unit and a stop unit which is used in an automobile or the like and is operated by hydraulic pressure or pneumatic pressure, and a method of manufacturing the same. The present invention relates to a body and a method for manufacturing the body.

[0002]

2. Description of the Related Art Conventionally, various cylinder parts have been proposed as cylinder parts used for brakes of automobiles and the like, for example, those for reducing the manufacturing cost (JP-A-63-275469). . FIG. 9A is a schematic sectional view showing a conventional one-end closed type cylinder body.
(B) is a schematic sectional view showing a conventional open-ended cylinder body. As shown in FIG. 9A, the one-end closed type cylinder body 11 has a cylindrical shape in which one end 11a is closed and the wall thickness is uniform. A flow port 12 for oil or air is formed in a side surface near the center in the longitudinal direction of the cylinder body 11, and a check valve 13 is disposed inside the flow port 12. Also, cylinder body 1
The opening end 11b has a slightly larger diameter, and a flange 14 is formed along the outer peripheral surface in the vicinity of the opening end 11b. The body 11 can be fixed.

Further, as shown in FIG. 9 (b), the cylinder body 11 may have an open end 11c, and the structure of other parts is the one-end closed type cylinder shown in FIG. 9 (a). Same as the body 11.

FIG. 10 is a sectional view showing a method for manufacturing a conventional one-end closed type cylinder body. Semi-cylindrical void 15a
And the two molds 15 and 16 having the gaps 15a and 16a are disposed so that the gaps 15a and 16a are opposed to each other. The core 17 that can be slid in the direction of the arrow in the drawing is inserted. Thereby, two molds 1
Since a cylindrical gap is formed between 5 and 16, the molten aluminum alloy is poured into the gap, cooled, and the molds 15, 16 and the core 17 are removed, so that the outer peripheral surface is formed. Flat cylindrical casting 22 with one end closed
Is prepared. Then, the circulation port 1 is placed at a predetermined position of the casting 22.
By forming 2 and the like, the cylinder body 11 can be manufactured.

[0005] The cylinder body 11 thus configured
In, a piston is disposed inside the cylinder, and the piston is moved to apply pressure to the air or oil filled in the cylinder body 11. Then, the air or oil inside the cylinder body 11 passes through the circulation port 12 and activates the driving device or the stopping device of the automobile connected thereto.

In recent years, in order to reduce the weight of automobiles and the like, their hydraulic and pneumatic cylinder parts have been used in place of cast iron parts replaced by lightweight aluminum alloy parts. When the cylinder part is made of an aluminum alloy, it is necessary to increase its thickness in order to obtain the same strength as that of the cylinder part made of cast iron. For example, pressure is applied to the cylinder body from inside. In consideration of safety, assuming an abnormality, etc., the cylinder body has a breaking strength (pressure resistance) of 500 kg / cm ² or more.
It is necessary to have

[0007]

However, recently,
Further reduction in weight of automobile parts is required, and when the cylinder body is made thinner to reduce the weight, there is a problem that the pressure resistance decreases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cylinder body made of an aluminum alloy, which is lightweight and has improved pressure resistance, and a method of manufacturing the same.

[0009]

The aluminum alloy cylinder body according to the present invention is made of a casting and is characterized in that it has a rib-shaped projection on the outer peripheral surface. Since the rib-shaped protrusion has an effect of reinforcing the cylinder body,
In the present invention, when it is intended to obtain a cylinder body having a pressure resistance equivalent to that in which no convex portion is formed, it is possible to reduce the wall thickness, thereby reducing the weight. it can.

The metal structure of the projection has a dendrite arm spacing (DAS) of 20.
It is preferably not more than μm. When the interval between the dendrite arms of the projections is reduced, that is, when the metal structure is refined, mechanical strength and elongation are improved. In the present invention,
When the rib-shaped protrusion is formed on the cylinder body and the interval between the second branches of the dendrite arm of the metal structure of the protrusion is 20 μm or less, the mechanical reinforcement effect by the rib-shaped protrusion and the fine structure of the structure can be obtained. Due to the synergistic effect with the strength improvement effect of the structure, the pressure resistance can be further improved, and the weight of the cylinder body can be further reduced.

It is preferable that the projection has a shape extending in the circumferential direction of the outer peripheral surface of the cylinder body. In a cylindrical cylinder body, the stress acting on its inner surface is highest in the circumferential direction. Therefore, when the rib-shaped protrusion is formed along the circumferential direction of the cylinder body to which the highest stress is applied, the pressure resistance can be further improved.

In the method of manufacturing an aluminum alloy cylinder body according to the present invention, an aluminum alloy melt is cast in a mold provided with a rib-shaped concave portion to manufacture a cylinder body having a rib-shaped convex portion on an outer peripheral surface. It is characterized by the following. As described above, when the cylinder body is manufactured by casting, since the rib-shaped protrusions on the outer peripheral surface of the cylinder body formed by the mold are surrounded by the mold, the heat transfer area increases, and the latent heat of solidification of the molten metal is reduced. Released rapidly. When the molten metal solidifies, the metal structure has the property of being finer as the cooling rate is higher. Therefore, in the present invention, using a mold provided with rib-shaped concave portions, the aluminum alloy molten metal is used. By manufacturing by casting, rapid cooling becomes possible, and the metal structure of the convex portion can be refined. Therefore, the cylinder body manufactured by the method of the present invention has a mechanical reinforcing effect by the rib-shaped protrusions,
By the synergistic effect with the strength improving effect by the micronization of the structure, the pressure resistance is improved, and the weight can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a schematic sectional view showing an aluminum alloy cylinder body according to an embodiment of the present invention. The cylinder body 1 has a cylindrical shape with one end 1a closed, and a plurality of rib-shaped protrusions 8 extending in the circumferential direction are formed on the outer peripheral surface. A flow port 2 for oil or air is formed on a side surface near the center in the longitudinal direction of the cylinder body 1.
Is provided with a check valve 3 therein. Further, the opening end 1b of the cylinder body 1 has a slightly larger diameter, and a flange 4 is formed near the opening end 1b along the outer peripheral surface. The flange 4 allows the cylinder body 1 to be fixed to other automobile parts.

FIG. 2 is a sectional view showing a method of manufacturing an aluminum alloy cylinder body according to an embodiment of the present invention.
First, two molds 5 and 6 having semi-cylindrical voids 5a and 6a are prepared, and these voids 5a and 6a are arranged to face each other. The molds 5 and 6 are provided with a plurality of rib-shaped recesses 9 extending in the circumferential direction on the side surfaces of the gaps 5a and 6a. Next, a core 7 having a columnar shape smaller than this region and being slidable in the direction of the arrow in the figure is inserted into the cylindrical gap region formed by the molds 5 and 6. As a result, a cylindrical gap is formed between the two molds 5 and 6. Then, after injecting the aluminum alloy molten metal into the gap, it is cooled and the mold 5,
By removing the core 6 and the core 7, a cylindrical casting 20 having a rib-shaped convex portion 8 on the outer peripheral surface and having one end closed. Thereafter, the cylinder body 1 is obtained by forming the flow openings 2 and the like at predetermined positions of the casting 20.

In the thus configured cylinder body 1, a piston is disposed inside the cylinder body 1, and the piston is moved to apply pressure to the air or oil filled in the cylinder body 1. Then, air or oil inside the cylinder body 1 passes through the circulation port 2 and
Activate the drive or stop of the vehicle connected to it.

In this embodiment, the rib-shaped projection 8 having the effect of reinforcing the cylinder body 1 is provided on the cylinder body 1.
Because it is formed on the outer peripheral surface, when trying to obtain the same pressure resistance as a conventional aluminum cylinder body,
The thickness can be reduced, and the weight can be reduced.

In FIG. 3, the vertical axis indicates the interval between the second branches of the dendrite arm having a metal structure, and the horizontal axis indicates the cooling rate.
It is a graph which shows the relationship between the dendrite arm 2nd branch space | interval of the C alloy casting, and the cooling rate at the time of casting. FIG. 4 is a graph showing the relationship between the metal structures of the AC4C alloy and the AC7A alloy and the mechanical properties, with the vertical axis representing the mechanical properties and the horizontal axis representing the microcrystal grains. As shown in FIG. 3, when the molten aluminum alloy solidifies, as the cooling rate increases, the interval between the second branches of the dendrite arm decreases, and the metal structure is refined. Then, as shown in FIG. 4, when the metal structure is refined, mechanical strength and elongation are improved.

According to the method of the present embodiment, since the rib-shaped protrusions 8 on the outer peripheral surface of the cylinder body 1 formed by the recesses 9 of the molds 5 and 6 are surrounded by the molds 5 and 6, heat is generated. The transmission area increases, and the latent heat of solidification of the poured aluminum alloy melt is rapidly released. As described above, when the aluminum alloy cylinder body 1 having the protrusions 8 on the outer peripheral surface is manufactured by casting, the cooling rate of the protrusions 8 is increased.
The metal structure can be easily miniaturized, and the mechanical strength and elongation of the projection 8 can be improved.

Therefore, in the present embodiment, the pressure-resistant strength can be further improved by the synergistic effect of the mechanical reinforcement effect by the rib-shaped projections 8 and the strength improvement effect by the finer structure. The thickness of the cylinder body can be reduced, thereby reducing its weight.

FIG. 5 is a schematic sectional view showing an example of a rib-shaped convex portion of the aluminum alloy cylinder body according to the embodiment of the present invention. In the present invention, for example, FIG.
Various projections such as a semicircular projection 8a as shown in FIG. 5A, a quadrangular projection 8b as shown in FIG. 5B, and a triangular projection 8c as shown in FIG. A convex portion having a cross-sectional shape can be formed on the outer peripheral surface of the cylinder body, and any convex shape can provide an effect of improving the pressure resistance.

In the present embodiment, the rib-shaped projection 8 is formed in a shape extending in the circumferential direction of the cylinder body 1. In the present invention, for example, the rib-shaped projection 8 is formed in a shape extending in the longitudinal direction of the cylinder body 1. Or a combination thereof. In addition, as for the casting method, in addition to the high-pressure casting, it can be manufactured by using a gravity mold casting method or a gravity sand casting method.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the aluminum alloy cylinder body according to the present invention will be specifically described below in comparison with comparative examples.

In this embodiment, a mold having a desired shape was prepared, a cylinder body made of an aluminum alloy was manufactured by a high-pressure casting method, the metal structure was observed under a microscope, and the product weight and pressure resistance were measured. . FIG. 6 is a sectional view showing the shape and size of the aluminum alloy cylinder body 1 of the embodiment. In both the example and the comparative example, the outer diameter is 50 mm and the length in the longitudinal direction is unified at 100 mm.
mm, the height was 2 mm, and the shape of the projection 8 was changed.
In the comparative example, the projection 8 was not formed, and the thickness was changed.

FIG. 7 is a photomicrograph showing the metal structure of the projection 8 of the aluminum alloy cylinder body manufactured by the method of the present embodiment. FIG. 8 is a microscope showing the metal structure of the aluminum alloy cylinder body of the comparative example. It is a photograph.
As shown in FIGS. 7 and 8, the cylinder body of the comparative example
While the interval between the dendrite arm second branches exceeds 20 μm, in the example, the interval between the dendrite arm second branches is 10 μm, indicating that the metal structure is finer than in the comparative example. Is shown.

The measurement results of the size, product weight and compressive strength of each of the examples and comparative examples are shown in Table 1 below. However, in the column of the convex shape, 8a, 8b, and 8c indicate the shapes of the convex 8a, the convex 8b, and the convex 8c shown in FIG. 5, respectively, and the radius of curvature of the convex 8a is 2 mm. , The width of the projection 8b is 3
mm, and the width of the bottom of the projection 8c was 4 mm. Also,
Regarding the pressure resistance, those having a breaking strength of 500 (kg / cm ² ) or more were evaluated as ○ (pass), 500 (kg / cm ² ).
Those having a breaking strength of less than m ² ) were evaluated as x (fail), and those having a failure strength were indicated in parentheses with the limit strength.

[0026]

[Table 1]

As shown in Table 1 above, Example No. The cylinder bodies Nos. 1 to 3 were able to obtain cylinder bodies having excellent pressure resistance even if the wall thickness was 3 mm. On the other hand, in Comparative Example No. 4
Nos. 6 to 6 were so thin that the required pressure resistance could not be obtained. Comparative Example No. In No. 7, the required pressure resistance was obtained because the wall thickness was 4 mm, but the weight of the product increased. As described above, when manufacturing the cylinder body so as to satisfy the required pressure resistance, the product weight of the comparative example is 177 g, whereas the product weight is 148 g in the example, and 29 g in the present example.
(16%) was achieved.

[0028]

As described in detail above, according to the present invention,
Since the outer peripheral surface of the aluminum alloy cylinder body has a rib-shaped protrusion, the pressure resistance can be improved,
Thereby, the thickness can be reduced and the weight can be reduced. If the convex portion has a shape extending in the circumferential direction of the cylinder body and the interval between the second branches of the dendrite arm of the metal structure is defined, the pressure resistance can be further improved, thereby reducing the weight of the cylinder body. It can be further reduced.

Further, according to the method of the present invention, since the aluminum alloy cylinder body having the rib-shaped protrusions on the outer peripheral surface is manufactured by casting, the mechanical reinforcement effect by the rib-shaped protrusions and the microstructure reduction Due to the synergistic effect with the strength improving effect of the present invention, it is possible to obtain a lightweight cylinder body having excellent pressure resistance.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an aluminum alloy cylinder body according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a method of manufacturing the aluminum alloy cylinder body according to the embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the dendrite arm second branch spacing of an AC4C alloy casting and the cooling rate during casting, with the vertical axis indicating the interval between the second dendrite arms of the metal structure and the horizontal axis indicating the cooling rate. FIG.

FIG. 4 is a graph showing a relationship between a metal structure of an AC4C alloy and an AC7A alloy and mechanical properties, with the vertical axis representing mechanical properties and the horizontal axis representing microcrystal grains.

FIG. 5 is a schematic cross-sectional view showing an example of a rib-shaped convex shape of the aluminum alloy cylinder body according to the embodiment of the present invention.

FIG. 6 is an aluminum alloy cylinder body 1 of the embodiment.
It is sectional drawing which shows the shape and size of a.

FIG. 7 is a photomicrograph showing the metal structure of the protrusion 8 of the aluminum alloy cylinder body manufactured by the method of the present embodiment.

FIG. 8 is a micrograph showing a metal structure of an aluminum alloy cylinder body of a comparative example.

9A is a schematic cross-sectional view showing a conventional one-end closed type cylinder body, and FIG. 9B is a schematic cross-sectional view showing a conventional double-ended open cylinder body.

FIG. 10 is a cross-sectional view illustrating a method for manufacturing a conventional one-end closed type cylinder body.

[Explanation of symbols]

 1, 11, 21; cylinder bodies 2, 12; flow ports 3, 13; check valves 4, 14, flanges 5, 6, 15, 16; molds 7, 17; Convex 9; Concave 20, 22; Casting

Claims (4)

[Claims] 1. A cylinder body made of an aluminum alloy, which is made of a casting and has a rib-shaped convex portion on an outer peripheral surface. 2. The aluminum alloy cylinder body according to claim 1, wherein the metal structure of the protrusion has a second dendrite arm second branch interval of 20 μm or less. 3. The aluminum alloy cylinder body according to claim 1, wherein the projection has a shape extending in a circumferential direction of an outer peripheral surface. 4. Manufacture of a cylinder body made of an aluminum alloy, characterized in that a molten aluminum alloy is cast in a mold provided with a rib-shaped concave portion to produce a cylinder body having a rib-shaped convex portion on an outer peripheral surface. Method.