Manufacturing method for a permeable die steel

Description

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a manufacturing method for a permeable die steel and more particular to a manufacturing method wherein a polymeric wire is installed in a molded die of green type and is vaporized by heating up the green type, so as to form a metallic product having breathing holes for being used as the die steel.

(b) Description of the Prior Art

As the advancement of technology in precision manufacturing, all kinds of design of mechanical and electronic products are toward “micro elements;” therefore, the manufacturing of die for the element is very important. However, as the die of element does not have a good permeability, streamers in a ripple shape are easily formed on a surface of element when performing an extrusion to the element, thereby affecting an outlook of element. In addition, for the element with a rather thin cross section, the element will be cracked or broken upon being pushed out due to a difference between inner and outer pressure when opening the die after being molded, thereby increasing the defect rate of element.

In order to overcome the drawback of imperfect permeability of a die, a permeable die is developed which is primarily made by a porous metal having permeability. The manufacturing method of porous metal is disclosed in Taiwan Utility Patent 593694, “Manufacturing Method for a Porous Metal of Micro Through-Hole Structure,” which is made primarily by the powder metallurgy method, according to the following operation procedure:

1. Dosing Operation

• • Powder of a pure metal or its alloy is chosen as a base material for sintering, and a tiny powder which can be solved in water or alkaline solvent is chosen as a fill material whose melting point should be higher than that of the base material used in sintering.

2. Sintering Coalesce Process

• • The aforementioned base material used in sintering and fill material are mixed together, along with adding in an adhesive and a plasticizer, such that the base material used in sintering and fill material can be uniformly distributed and stacked tightly. Next, they are dried, fixed, and preheated, so as to remove the moisture in the fill material, followed by sintering at a sintering temperature, to manufacture a metallic green type which is provided with a high density and micro granular structure.

3. Fill Material Removing Operation

• • A compatible solvent is chosen according to the chemical properties of aforementioned metallic green type that the fill material can be solved in water or alkaline solvent, and the fill material in the metallic green type is resolved and removed in a ultrasonic cleaning sink, by a cavitation effect of ultrasonic wave, so as to obtain a porous semi-finished product of tiny through-hole structure formed by the base material used in sintering.

4. Cleaning Operation

• • Fresh water is used to clean up the residual solvent between the walls of through-holes of the aforementioned semi-finished product.

5. Drying Operation

• • Residual moisture between the walls of through-holes of the semi-finished product from the aforementioned cleaning operation is dried, so as to manufacture a porous metallic product having the tiny through-hole structure.

Accordingly, the porous metal with tiny through-hole structure manufactured from the aforementioned procedure can be used to manufacture a permeable die. However, as internal breathing holes of the porous metal with the tiny through-hole structure are aligned irregularly, it is unable to effectively control a size, position, and continuity in molding the breathing holes, upon manufacturing with the powder metallurgy technique. Therefore, once each breathing hole cannot be connected continuously, which generates a discontinuity condition, the permeability will not be achieved and the function of permeability cannot be assured perfectly; thus it is still not quite perfect in application.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a manufacturing method for a metallic product having breathing holes, such that a product made by the present invention can be used as a die material which can balance a difference between inner and outer pressure through a function of permeability, and prevent a molded element from being damaged upon opening a die of the molded element. Quantity, position, and porosity of the aforementioned breathing holes can all be controlled in the manufacturing process.

The procedure of present invention includes:

A. Constructing a Molded Die

• • A molded die with an emplacing space is formed by stacking and fixing with fixing blocks, and a polymeric wire is fixed inside the emplacing space.

B. Forming a Green Tap

• • A metallic powder and an adhesive are emplaced in the emplacing space of fixing blocks to completely enclose the polymeric wire after being mixed together, thereby manufacturing a green type.

C. Molding by Heating Up

• • The green type is heated up such that the polymeric wire enclosed in the green type is completely vaporized, so as to form breathing holes in the green tap.

D. Forming a Metallic Product

• • The green type is cooled down to mold into the metallic product having breathing holes.

The aforementioned wire is linearly configured.

The aforementioned wire can be also configured in a mesh.

The present invention is provided with following advantages:

• • 1. By using fixing blocks to stack into a molded die having an emplacing space, and fixing a polymeric wire between the fixing blocks, the manufacturing process of forming breathing holes by heating up the polymeric wire to vaporization, after manufacturing a green type, is simple, and a shape, position, size, and quantity of the breathing holes can be accurately controlled.
  • 2. The process of vaporizing polymeric wire will not affect a solidification of green type; therefore, a finishing time will not be increased.
  • 3. By using a high temperature to vaporize and remove the polymeric wire, the process of oxidation is simple and accurate.

To enable a further understanding of the said objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flow diagram of manufacturing of the present invention.

FIG. 2 shows a schematic view of stacking a molded die of the present invention.

FIG. 3 shows a schematic view of a polymeric wire of the present invention.

FIG. 4 shows a schematic view of forming a green type of the present invention.

FIG. 5 shows a relation between a heating-up time and temperature rise of the present invention.

FIG. 6 shows a cutaway view of a metallic product of the present invention.

FIG. 7 shows a schematic view of a metallic product installed in a die of the present invention.

FIG. 8 shows a perspective view of components of another implementation of the present invention.

FIG. 9 shows a cutaway view of another implementation after being assembled of the present invention.

FIG. 10 shows a perspective view of components of still another implementation of the present invention.

FIG. 11 shows a cutaway view of still another implementation after being assembled of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, the procedure of present invention is as follow:

A. Constructing a Molded Die

• • As shown in FIG. 2, four fixing blocks 2 are stacked at fixed on a top periphery of plate 1 to constitute a molded die with an emplacing space 21. A plurality of tiny through-holes 22 are aligned on the fixing block 2 by an equal distance (as shown in FIG. 3), and a polymeric wire 23 is connected in each of the through-holes 22 on the fixing blocks 2. These crisscrossed polymeric wires 23 can be densely spreading over an interior of emplacing space 21 of fixing blocks 2. In addition, different shape of fixing block 2 of the molded die can be chosen according to a shape required by the die.

B. Forming a Green Type

• • As shown in FIG. 4, a metallic powder and an adhesive are emplaced and completely filled in the emplacing space 21 of fixing blocks 21 to enclose the polymeric wires 23 after being mixed together, thereby forming a green type 3.

C. Molding by Heating Up

• • The green type 3 is installed in a sintering furnace to be heated up. As shown in FIG. 5, the green type 3 is continuously heated up to 300° C. at a rising speed of 3° C. per minute, and is then controlled at a constant temperature of 300° C. for one hour.

After that, it is continuously heated up to 600° C. at a rising speed of 3° C. per minute again, and is then controlled at a constant temperature of 600° C. for one hour, followed by rising continuously to 900° C. at a rising speed of 3° C. per minute. Finally, the heating up can be stopped after controlling the green type 3 at a constant temperature of 900° C. for one hour. During the process of heating up the green type 3 from 300° C. to 600° C., the polymeric wires 23 enclosed in the green type 3 can be totally vaporized; thereby forming intertwined breathing holes 31 in the green type 3.

D. Forming a Metallic Product

• • The green type 3 stops being heated up and is gradually cooled down to room temperature to form a metallic product 3A having the breathing holes 31.

Referring to FIG. 7, the aforementioned metallic product 3A can be pre-configured to a required shape in the aforementioned step A of constructing a molded die; therefore, the metallic product 3A having the breathing holes 31 can be assembled into a proper position of die 4, after a simple modification to its surface precision. As the proper position is usually where the die 4 needs ventilation; therefore, there will be no blocking of ventilation to the die 4, by the permeability of breathing holes 31 in the aforementioned metallic product 3A. Accordingly, there will be no pressure difference upon opening the die for a molded element 5, thereby assuring a good quality of the molded element 5.

Referring to FIG. 8 and FIG. 9, it shows another implementation of the present invention. In the step A of constructing a molded die, each of a plurality of frame-shape fixing blocks 6 is stacked on a top of another block 6 and fixed on a plate 1, and a mesh-shape polymeric wire 7 is installed between the neighboring two fixing blocks 6. A molded die having an emplacing space 61 is formed after stacking the fixing blocks 6, and the mesh-shape polymeric wires 7 are layered in the emplacing space 61 by a proper distance of separation. In addition, a metallic product having breathing holes is formed through the step B of forming a green type, the step C of molding by heating up, and the step D of forming a metallic product, respectively.

Referring to FIG. 10 and FIG. 11, it shows still another implementation of the present invention. In the step A of constructing a molded die, a plurality of polymeric wires 81 are transfixed vertically into a plate 8, each of a plurality of frame-shape fixing blocks 6 is stacked on a top of another block 6 and fixed on the plate 8, and a mesh-shape polymeric wire 7 is installed between the neighboring two fixing blocks 6. A molded die having an emplacing space 61 is formed after stacking the fixing blocks 6, and the vertical polymeric wires 81 and the mesh-shape polymeric wires 7 are located in the emplacing space 61 by a proper distance of separation, respectively. A metallic powder and an adhesive are emplaced in the aforementioned emplacing space 61 after being mixed together, and their top end is covered with a cover plate 9 which is provided with through-holes 91 corresponding to the polymeric wires 81, such that the polymeric wires 81 can be transfixed and fixed. Following that, a metallic product having breathing holes is formed through the step B of forming a green type, the step C of molding by heating up, and the step D of forming a metallic product, respectively.

It is of course to be understood that the embodiments described herein is merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.