CN1603058A - Method for Improving Excessive Polishing of Cavity Edge of Injection Molding Cavity - Google Patents

Abstract

The invention provides a method for manufacturing a master mould cavity of an injection moulding mould, which can avoid the phenomenon of over-polishing of the edge of the mould cavity of the master mould cavity. An auxiliary fixture is used to protect the cavity during polishing, the auxiliary fixture having a central hole substantially conforming to the shape of the edge of the cavity. The manufacturing method comprises the following steps: and forming a corresponding fixing structure and a corresponding positioning structure on a die cavity rough blank and the auxiliary clamp. The auxiliary clamp can be positioned on the die cavity rough blank through the positioning structure, and the relative relation between the auxiliary clamp and the die cavity rough blank is kept fixed through the fixing structure. And performing an electric discharge machining process on the combined body formed by the auxiliary fixture and the die cavity rough blank by using an electrode. So as to manufacture the required female die cavity in the central concave die cavity. A polishing process is performed on the assembly. And finally, loosening the fixing structure, and removing the auxiliary clamp from the upper part of the female mold cavity, so that the complete and satisfactory female mold cavity can be obtained for subsequent injection molding procedures.

Description

Method for Improving Excessive Polishing of Cavity Edge of Injection Molding Cavity

technical field

The invention relates to a method for avoiding excessive polishing of the mold cavity edge of an injection molding female mold cavity.

Background technique

Many plastic injection molded products, such as casings of mobile phones, digital cameras, etc., need to be produced using master mold cavities. A master mold cavity is often used to produce more than 10,000 plastic injection molded parts (jnjected parts). Therefore, the quality of the master mold cavity affects the quality of the entire batch of plastic injection molded parts. The master cavity must undergo a polishing procedure to make the surface inside the cavity of the master cavity smoother for injection molding. However, during polishing, the edge of the mold cavity of the female mold cavity is often slightly deformed due to excessive polishing.

Referring to FIG. 1 , FIG. 2A and FIG. 2B , FIG. 1 is a schematic diagram of a known female mold cavity 10 . FIG. 2A is a schematic diagram of the deformed mold cavity edge 12 of the female mold cavity 10 in FIG. 1 , and FIG. 2B is a schematic diagram of the undeformed mold cavity edge 12B corresponding to FIG. 2A . The unexpected deformation of the cavity edge 12 of the female mold cavity caused by excessive polishing is roughly shown in Figure 2A, while the expected cavity edge 12B when manufacturing the female cavity is shown in Figure 2B, and the deformation can be seen by comparing the two The degree of deformation is not serious, and the degree of this deformation is still within the allowable range in the known technology. However, the deformation of the female mold cavity will eventually affect the injection molded product, and with repeated production and repeated use of the female mold cavity, the degree of deformation will become more and more serious.

Referring to FIG. 3 , FIG. 3 is an appearance view of an injection molded product 30 produced by using the female mold cavity 10 in FIG. 1 . The injection molded product 30 produced by the female mold cavity 10 is a front shell of a mobile phone, which can be joined with a rear shell to form a complete shell of the mobile phone. It can be seen from the partially enlarged part in FIG. 3 that due to the deformation of the cavity edge 12 of the female mold cavity (FIG. 2), the joint edge 32 of the injection molded product 30 forms a corresponding wing-like protrusion (burr) 33, or "burr". ". The wing-like protrusions 33 are not an expected result when producing the injection molded product 30 . However, since it is known that the maintenance process of the female mold cavity is not easy to avoid excessive polishing, the deformation of the cavity edge 12 of the female mold cavity often occurs, and therefore, unexpected wing-like protrusions 33 appear on the joint edge 32 of similar injection molded products quite common. In the known technology, such burrs are not easy to avoid, so such burrs must be tolerated or the injection molded product must be subsequently processed to deal with the burrs.

When a whole batch of plastic injection molded products is manufactured by using the female mold cavity, so-called burrs are usually formed on the edge, which is caused by the deformation of the mold cavity edge of the female mold cavity due to excessive polishing. Therefore, the prior art lacks a method for improving the over-polishing of the cavity edge of the female mold cavity in order to avoid the formation of burrs.

Contents of the invention

The main purpose of the present invention is to provide a method for improving the excessive polishing of the mold cavity edge of the injection molding female mold cavity.

The invention provides a method for avoiding collapse and deformation of the edge of the cavity of an injection mold cavity used for injection molding. The method of the present invention utilizes an auxiliary fixture to protect the cavity of the mother mold during polishing. The auxiliary fixture has a central hollow that roughly conforms to the shape of the edge of the mold cavity. The manufacturing method of the present invention includes the following steps: forming corresponding fixing structures and positioning structures on a non-machined cavity and auxiliary fixtures. Through the positioning structure, the auxiliary clamp can be positioned on the rough blank of the mold cavity, and through the fixing structure, the relative relationship between the auxiliary clamp and the rough blank of the mold cavity can be kept fixed. An electrical discharge machining procedure (electrical discharge machining procedure) is performed on the assembly formed by the auxiliary fixture and the mold cavity rough blank with an electrode to produce the required female mold cavity in the central concave mold cavity. A polishing procedure is performed on the assembly. The fixing structure is loosened, and the auxiliary fixture is removed from the cavity of the female mold, so that a complete and satisfactory cavity of the female mold can be obtained for subsequent injection molding procedures.

The invention can avoid excessive polishing on the edge of the mold cavity of the female mold cavity. The mobile phone casing or the digital camera casing produced by the subsequent injection molding process of the master mold cavity manufactured by the method of the present invention can avoid burrs.

The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the accompanying drawings.

Description of drawings

FIG. 1 is a schematic diagram of a known female mold cavity 10 .

FIG. 2A is a schematic diagram of the deformed mold cavity edge 12 of the female mold cavity 10 in FIG. 1 .

FIG. 2B is a schematic diagram of the undeformed cavity edge 12B corresponding to FIG. 2A .

FIG. 3 is an external view of an injection molded product 30 produced using the female mold cavity 10 in FIG. 1 .

FIG. 4 is a schematic diagram of a blank 50 of a female mold cavity of the present invention.

FIG. 5 is a top view of the auxiliary clamp 60 of the present invention.

FIG. 6 is a bottom view of the auxiliary fixture 60 in FIG. 5 .

FIG. 7 is an exploded view before the auxiliary fixture 60 is combined with the mold cavity blank 50 .

FIG. 8 is a schematic diagram of an assembly 70 in which the auxiliary fixture 60 and the mold cavity blank 50 in FIG. 7 are combined.

FIG. 9 is a schematic diagram of the assembly 70 of FIG. 8 undergoing an electrical discharge machining procedure.

FIG. 10 is a schematic diagram of a polishing procedure for the assembly 70 after the electrical discharge machining in FIG. 9 .

FIG. 11 is an exploded schematic view of the assembly 70 in FIG. 10 .

Fig. 12 is a schematic diagram of the master mold cavity 75 completed for the present invention.

Fig. 13 is a flow chart of the manufacturing method of the female mold cavity of the present invention.

Explanation of reference numbers:

10, 50 female mold cavity 12 mold cavity edge

30 plastic finished product 32 joint edge

33 wing-shaped protruding 50 cavity rough embryo

52 mold cavity 54 positioning concave hole

60 auxiliary fixture 62 positioning boss

64 screw holes 66 positioning bosses

68 screws 70 assembly

72 Electrodes 74 Polishers

76 cavity edge

Detailed ways

The invention provides a method for manufacturing a jnjection mold cavity for injection molding, which can avoid excessive polishing on the edge of the cavity of the jnjection mold cavity. The method of the present invention utilizes an auxiliary fixture to protect the cavity of the mother mold during polishing. The auxiliary jig has a central hollow substantially conforming to the shape of the edge of the cavity of the rough mold. The so-called over-polishing phenomenon refers to the unexpected deformation (deform) formed during the polishing of the edge of the cavity of the female mold cavity or the edge of the central hole of the auxiliary fixture.

Referring to FIG. 4 , FIG. 4 is a schematic diagram of a blank 50 of a female mold cavity of the present invention. The female mold cavity rough blank 50 used in the present invention has a mold cavity 52, and has three positioning concave holes 54 (setting holes) and four screw holes 56 (screw holes).

Referring to FIG. 5 and FIG. 6 , FIG. 5 is a top view of the auxiliary clamp 60 of the present invention, and FIG. 6 is a bottom view of the auxiliary clamp 60 in FIG. 5 . The present invention uses an auxiliary fixture 60 to protect the cavity of the master mold during polishing. The auxiliary fixture 60 has a central hollow 62 substantially conforming to the shape of the edge of the cavity 52 of the cavity blank 50 . As shown in FIG. 5 , the auxiliary fixture 60 also has four screw holes 64 corresponding to the screw holes 56 of the cavity blank 50 . As shown in FIG. 7 , the auxiliary fixture 60 also has three positioning bosses 66 corresponding to the positioning holes 54 of the cavity blank 50 .

The mold cavity blank 50 is formed by milling a steel material to form a mold cavity 52 with a concave center. In the present embodiment, the material of the mold cavity blank 50 is selected as AISI 420 stainless steel or steel of the same grade. The auxiliary jig 60 is formed of another steel material. The steel material of the auxiliary clamp 60 is thermal treatment steel (thermal treatment steel), and is preferably softer than the steel material of the rough blank of the mold cavity. In the present embodiment, the material of the steel of the auxiliary fixture 60 is selected as NAK 80.

Referring to FIG. 7 and FIG. 8 , FIG. 7 is an exploded view of the auxiliary fixture 60 and the cavity blank 50 before being combined, and FIG. 8 is a schematic diagram of a combination 70 of the auxiliary fixture 60 and the cavity blank 50 in FIG. 7 . The side of the auxiliary fixture 60 having the positioning post 66 is used to engage with the cavity blank 50 . Utilize the positioning concave hole 54 of the mold cavity rough blank 50 and the positioning convex post 66 of the auxiliary clamp 60 to form corresponding positioning structures (positioning structures), which can make the auxiliary clamp 60 be positioned on the mold cavity rough blank 50, so that the central hole 62 is aligned with the mold cavity 52 edges. After the central hole 62 is aligned with the edge of the mold cavity 52, the fixing structures (fixing structures) formed by the screw holes 56 of the mold cavity rough blank and the screw holes 64 of the auxiliary fixture 60 and four corresponding screws 68 can be further used to make the auxiliary fixture The relative relationship of 60 and cavity blank 50 is kept fixed. That is to say, through this positioning structure, the auxiliary clamp 60 can be positioned on the rough cavity blank 50 , and through this fixing structure, the relative relationship between the auxiliary clamp 60 and the cavity blank 50 can be kept fixed. In this way, the auxiliary jig 60 and the cavity blank 50 can be combined to form an assembly 70 .

The positioning structure and the fixing structure can have various changes. For example, regarding the positioning structure, the positioning bosses can be formed on the mold cavity blank 50 , and the positioning concave holes can be formed on the auxiliary jig 60 , which are well known in the prior art and will not be repeated here.

Referring to FIG. 9 , FIG. 9 is a schematic diagram of the assembly 70 of FIG. 8 undergoing an electrical discharge machining process. An electrode (electrode) 72 is used to perform electrical discharge machining (Electrical discharge machining, EDM) on the assembly 70 formed by the auxiliary fixture 60 and the mold cavity rough blank 50, so as to produce the required mother mold cavity in the central concave mold cavity .

Referring to FIG. 10 , FIG. 10 is a schematic diagram of a polishing procedure for the assembly 70 after the electrical discharge machining in FIG. 9 . After the electrical discharge machining procedure, a polisher (polisher) 74 is used to perform a polishing procedure on the assembly 70 formed by the auxiliary fixture 60 and the rough mold 50 . When the assembly 70 is polished, the over-polishing phenomenon will only appear on the edge of the central hole 62 of the auxiliary jig 60 , but not on the edge of the mold cavity of the rough mold 50 . The present invention utilizes the auxiliary jig 60 instead of the rough mold 50 to form unintended deformation during polishing, and sacrifices the auxiliary jig 60 to maintain the integrity of the mold cavity edge of the predetermined female mold cavity.

Referring to FIG. 11 , FIG. 11 is a schematic exploded view of the assembly 70 in FIG. 10 . After the polishing procedure, the screw 68 is unscrewed to loosen the fixing structure of the assembly 70 and the auxiliary fixture 60 is removed. In this way, the female mold cavity 75 can be subjected to subsequent injection and alignment procedures.

Referring to FIG. 12, FIG. 12 is a schematic diagram of a female mold cavity 75 completed for the present invention. It can be seen from the mold cavity edge 76 of the female mold cavity 75 that the female mold cavity 75 manufactured by the method of the present invention can avoid excessive polishing, and the mold cavity edge 76 has no unexpected deformation after polishing. In the embodiment of FIG. 12, the female mold cavity 75 is used to produce an injection molded mobile phone casing. Since the rough mold 50 is protected by an auxiliary fixture 60 placed above it during the process of the electric discharge machining program and the polishing program, it is possible to avoid the edge damage and deformation of the produced mother mold cavity 75, and to prevent the rough mold cavity 75 from being damaged and deformed according to the master mold. The injection molded mobile phone casing produced by the cavity 75 exhibits flashing.

It is used in the mass production of injection molded products. After multiple injection molding procedures, the edge of the mold cavity may be damaged and deformed, and it must be re-polished. At this time, the positioning structure and the fixing structure can be used, and then the auxiliary fixture can be combined with the mother cavity. On the mold cavity, and then further polishing process to repair the damaged and deformed mold cavity edge of the mother mold cavity.

Referring to Fig. 13, Fig. 13 is a flow chart of the method for manufacturing the female mold cavity of the present invention. The manufacturing method of the present invention is used to manufacture a master mold cavity for producing injection molded products, such as a master mold cavity for producing a casing of a mobile phone or a casing of a digital camera. Manufacturing method of the present invention comprises the following steps:

Step 800: start.

Step 802 : Perform a milling process to form a mold cavity 52 on the mold cavity blank 50 and a central hole 62 on the auxiliary jig 60 .

Step 804 : forming corresponding positioning structures on the cavity blank 50 and the auxiliary fixture 60 , such as the positioning concave holes 54 and the positioning protrusions 66 .

Step 806 : Form corresponding fixing structures on the cavity blank 50 and the auxiliary fixture 60 , such as screw holes 56 and screw holes 64 .

Step 808 : Position the auxiliary fixture 60 on the mold cavity blank 50 through the positioning structure, and fix the mold cavity blank 50 and the auxiliary fixture 60 through the fixing structure to form the assembly 70 .

Step 810 : Perform electrical discharge machining (EDM) on the assembly 70 .

Step 812 : Perform polishing on the assembly 70 .

Step 814: Loosen the fixing structure, and remove the auxiliary fixture 60 from above the cavity of the female mold.

Compared with the known technology, the method for manufacturing the female mold cavity for injection molding of the present invention utilizes an auxiliary tool, and the auxiliary tool has a central hole roughly conforming to the shape of the cavity edge of the female mold cavity. Since the rough mold cavity is protected by an auxiliary fixture placed above during the EDM process and polishing process, the edge of the produced mother mold cavity can be prevented from being damaged and deformed. The present invention can avoid over-polishing phenomenon on the edge of the mold cavity of the female mold cavity, and the injection molded product produced by the subsequent injection molding process of the female mold cavity manufactured according to the method of the present invention can avoid the occurrence of burrs.

Through the detailed description of the preferred specific embodiments above, it is hoped that the features and spirit of the present invention can be described more clearly, and the scope of the present invention is not limited by the preferred specific embodiments disclosed above. On the contrary, the intention is to cover various modifications and equivalent arrangements within the scope of the appended claims of the present invention.

Claims (10)

1. A method of manufacturing a female die cavity for injection molding, the method is to utilize an auxiliary fixture with a central hole, the method of manufacturing comprises the following steps: Fixing the auxiliary fixture on a mold cavity blank, the rough mold has a mold cavity, and the edge shape of the mold cavity is roughly the same as the central hole; Using an electrode to perform electrical discharge machining on the assembly formed by the auxiliary fixture and the cavity rough blank, so as to produce the required female mold cavity; performing a polishing procedure on the assembly; and The auxiliary fixture is removed from the female mold cavity to obtain the female mold cavity. 2. The manufacturing method according to claim 1, wherein the mold cavity rough blank is formed by milling a central concave mold cavity from a first steel material, and the auxiliary fixture is formed by a first steel material having the central hole Two steel materials are formed. 3. The manufacturing method according to claim 2, wherein the second steel material is heat-treated steel and softer than the first steel material. 4. The manufacturing method according to claim 2, wherein the material of the first steel is selected as AISI 420 or the same grade, and the material of the second steel is selected as NAK 80. 5. The manufacturing method according to claim 1, wherein a corresponding fixing structure is formed on the rough mold and the auxiliary fixture, and the fixing structure enables the relative relationship between the auxiliary fixture and the rough mold to be kept fixed . 6. The manufacturing method according to claim 5, characterized in that: the fixing structure includes a plurality of corresponding screw holes arranged on the rough mold and the auxiliary fixture, and the auxiliary fixture and the rough fixture can be connected by a plurality of screws. Die fixed for this assembly. 7 . The manufacturing method according to claim 1 , wherein a corresponding positioning structure is formed on the mold cavity blank and the auxiliary jig, so that the auxiliary jig can be positioned above the mold cavity blank. 8 . 8. The manufacturing method according to claim 7, characterized in that: the positioning structure includes a plurality of positioning concave holes and positioning protrusions correspondingly arranged on the rough blank of the mold cavity and the auxiliary fixture, through these positioning concave holes Cooperating with the positioning boss, the auxiliary fixture can be positioned on the rough blank of the mold cavity. 9. The manufacturing method as claimed in claim 1, wherein the injection molded product produced by the female mold cavity is a casing of a mobile phone. 10 . The manufacturing method according to claim 1 , wherein the injection molded product produced by the mother mold cavity is a casing of a digital camera. 11 .

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