JPS6294314A - Preparation of packing and molding die therefor - Google Patents

Abstract

PURPOSE:To form the easily separable burr and to prevent the production of defective molding, by interconnecting the one split mold a part to be an inside region of cavity, and by boring the burr relief gate of a diameter slightly smaller than that of cavity in this region in said part and by flowing a part of form green material into the burr relief gate. CONSTITUTION:At upper split mold 1, the burr relief gate 5 of slightly smaller than inner diameter D of cavity 3 is formed, penetrating from inner part of cavity 3 at the position of an opposite side 1' of lower split mold 2 into the outside 1''. Plasticized green rubber A is filled into the cavity 3 and an outer burr slot 4, and a part of its green rubber flows into the burr relief gate 5 together with air existing in cavity 3 etc., then a product 6 inside the cavity 3 and burr 7 and 8 inside the outer burr groove 4 and burr relief gate 5 are respectively formed by crosslink curing. Among them, inner burr 8 is scattered by injecting the compressed air 9 into the burr relief gate 5 under closing the mold and it can be easily removed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a packing such as an O-ring that is a sealing member, and a mold used in the manufacturing, and particularly to a product in which the packing has an extremely small diameter. One of the purposes is to easily separate the part and the burr part.
- [Prior Art] Conventionally, a method of manufacturing packing using a mold as shown in FIG. 5 has been known.

That is, in the same figure, symbols (al) and (a2) are a pair of upper and lower split types that can be relatively separable, and both split types (al) (
An annular molding cavity (b), an outer periphery burr groove (C), and an inner periphery burr groove (d) are separately formed on the mutually opposing surfaces (ai) of (a). To manufacture a packing (0-ring) using this mold, first, a rubber dough (not shown) is inserted between the two split molds (al) (a2), and the molds are clamped while heating. At this time, the plasticized rubber fabric flows through the gap between the two split molds (a,) (a2) and into the cavity (b) and the outer and inner burr grooves (c) (
d) is filled in. Thereafter, the mold is opened after the rubber crosslinks and hardens, and the rubber molded product shown in FIG. 6 is taken out. In the next step, this rubber molded product is separated into a product part (e) (packing) and an outer/inner periphery burr part (D(g)).

[Problem that the invention seeks to solve]

However, if the inner diameter (b) of the packing (e) is relatively large, the burr (g) may be removed by hand or a punch (not shown) may be used in the separation process of the inner periphery burr (g). However, if the inner diameter (D) of the packing (e) is extremely small (3 mm or less), it is especially difficult to separate the burr (g) on the inner periphery. It is very difficult to remove the burr (as shown in Fig. 7).
A protrusion (go) is formed on g), and the worker has to pinch the protrusion (go) with tweezers or the like and pull it out one by one to separate it, resulting in extremely poor workability.

Furthermore, since the above-mentioned mold is not provided with an air escape path, it also has the disadvantage that air gets mixed into the cavity (b) during molding, which tends to cause molding defects.

[Means for solving problems]

In view of the above-mentioned problems, the present invention includes drilling a burr relief hole in one of the split molds, which communicates with the inner circumferential side of the cavity and has a diameter slightly smaller than the inner diameter of the cavity at least in this part. During molding, a part of the molding dough is allowed to flow out into the burr relief hole using a molding die of 1 to form a burr that can be easily separated from the chain portion.

[For production]

According to the present invention, during molding, since the air in the cavity flows out to the burr relief hole together with a part of the molding dough,
It is possible to prevent molding defects due to air remaining in the cavity, and the burrs formed in the burr relief hole on the inner peripheral side of the product part can be removed while the mold remains in the clamped state. It can be easily separated from the product part by a method such as injecting compressed air into the escape hole or at the same time as opening the mold.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view of a mold used in the first embodiment method, in which symbols (1) and (2) are a pair of lower -F split molds that can be relatively separated, and (3) is a cross-sectional view of the two split molds ( 1) Opposite surface (lo) of (2)
An annular molding cavity divided into (2°), (
4) is an outer periphery burr groove which is similarly divided and formed concentrically on the outer periphery of the cavity (3). In addition, both split type (1) (
Among 2), the upper split mold (1) has a hole that penetrates from the inner circumference of the cavity (3) to the outer surface (!'') on the surface (lo) facing the lower split mold (2). The cavity (3
) has a slightly smaller diameter than the inner diameter (D) of the burr relief hole (5)
is formed by drilling. Using this mold, packkin (
6: See Fig. 2) As before, first insert the rubber dough (A: see Fig. 2) between the two split molds (1) and (2), and tighten the mold while heating. Let's do it. Along with this, the plasticized rubber fabric (A) is divided into two split types (1) (2).
) while flowing through the gap between the opposing surfaces (1') and (2'),
As shown in Fig. 2, the cavity (3) and the outer periphery burr groove (0) are filled, and some of it is filled with the air (not shown) that was inside the cavity (3) etc. and the burr relief hole (5).
burrs (7) and (8) are formed in the product part (B) (puffkin), the outer periphery burr* (4), and the burr relief hole (5) in the cavity (3) by crosslinking and curing. Ru. Among these, the inner periphery burr (8) is removed by compressed air (8) into the burr release hole (5) while the mold is in a clamped state.
) can be easily removed by spraying the burr to the outside of the burr relief hole (5), so there is no need to remove it one by one using a bottle set after opening the mold as in the past. In particular, the inner diameter of the product part (8) (
When D) has an extremely small diameter, workability is greatly improved.

Next, FIG. 3 shows a mold used in the method of the second embodiment, and to describe the difference from the first embodiment, the burr relief hole (5) is formed in the lower part of the upper part mold (1). The opening (5a) on the surface (lo) side facing the mold (2) (the inner circumferential side of the cavity (3)) has a slightly smaller diameter than the inner diameter ([1) of the cavity (3), and the outer diameter Each burr relief hole (5) is formed in a tapered shape that becomes larger in diameter toward the opening (5b) on the side surface (l'') side, and is formed on the outer surface (1'').
Grooves (lO) are carved to connect the burrs, and by molding using this mold, the grooves are formed in the burr relief holes (5) as shown in Figure 4. Inner burrs (8°
)... are suddenly separated from the product part (8) at the same time as the mold is opened.

〔Effect of the invention〕

As explained above, the present invention utilizes a mold having a burr relief hole for forming easily separable burrs on the inner circumferential side of the cavity in the production of packing. Since the air in the cavity flows out into the burr relief hole along with a part of the dough, it is possible to prevent molding defects due to residual air in the cavity. The burrs can be removed all at once by spraying compressed air while the mold is closed, or when the mold is opened, and there is no need to remove the burrs one by one using tweezers, reducing the number of man-hours. This method is particularly effective when the inner diameter of the packing to be manufactured is small, for example, 3 cm or less.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main part of a mold used in the first embodiment method according to the present invention, FIG. 2 is a cross-sectional view of the main part showing the manufacturing process using the same mold, and FIG. FIG. 4 is a cross-sectional view of the main part of the mold used in the example method, FIG. 4 is a cross-sectional view of the main part showing the manufacturing process using the same mold, and FIG. 5 is an example of the mold used in the conventional manufacturing method. FIG. 6 is a cross-sectional view of a main part of a molded product made by the same mold, and FIG. 7 is a cross-sectional view of a main part of a molded product made by another conventional mold. (1) (2) Split type (3) Cavity (0 outer periphery burr groove (5) Burr release hole (8) Product part (packet) (7) (e) (so)
Burr (lO) groove (A) Rubber fabric Fig. 1 Fig. 2

Claims (2)

[Claims] (1) In a packing manufacturing method in which a molding dough is filled into an annular cavity formed between a pair of split molds, and after the dough has hardened, the mold is opened to take out the product. A burr relief hole is drilled that communicates with the inner peripheral side of the cavity and has a diameter slightly smaller than the inner diameter of the cavity at least in the portion, and during molding, a part of the molding dough is passed into the burr relief hole. By letting it flow,
A method for manufacturing a packing, characterized in that an easily separable burr is formed in the portion. (2) One of the pair of split molds in which an annular cavity is formed is connected to a portion on the inner peripheral side of the cavity, and at least in the portion, the diameter is slightly smaller than the inner diameter of the cavity. A packing mold characterized by having a burr relief hole.