JP6294756B2 - Mold structure and seal manufacturing method - Google Patents

Description

The present invention relates to a molding die structure and a seal manufacturing method .

In general, a molding die structure for injection molding or compression molding of a seal such as an O-ring is provided with a pair of molds whose parting surfaces are superposed and separable from each other. A cavity groove and a sub-groove disposed in the vicinity of the groove are recessed, and a belt-like parallel surface having a minute gap is provided between the cavity groove and the sub-groove. A film-like communication path was formed by the parallel surfaces.
Therefore, a seal manufactured from such a molding die is connected to an annular burr portion having a slightly large cross-sectional area (formed by a secondary groove) via an annular band-shaped film portion. The film part and the annular burr part are integrally taken out from the molding die (see Patent Document 1).
When separating the seal from the removed molded rubber product, it may be difficult for the film part of the burr to separate from the seal, and further, there is a problem that the film part tears off (rips off) a part of the seal part. It was.

JP-A-62-167013

By the way, the above-described molding die of Patent Document 1 is a die for molding a simple O-ring, and the O-ring (seal) is independently taken out from the parting surface.
Recently, a molding method has been proposed in which a large number of seals are connected to each other with a planar film from a mold and taken out into a sheet shape. The present inventors are intensively researching and developing a molding method in which a large number of molds are taken out simultaneously.
A seal having a complicated cross-sectional shape such as a U-packing needs to be manufactured by shifting the parting line. However, if the parting line is shifted, it is difficult to make the burr thickness uniform in terms of mold production. The burr thickness is different between the inner diameter side and the outer diameter side. May be excessive.
As described above, when the burr thickness is excessive, it is difficult to separate the molded product and the burr. Moreover, if the burrs are forcibly separated and removed, the molded product itself is deficient.

Therefore, the present invention can take out a large number of seals having a complicated cross-sectional shape as a molded product at the same time in the form of a sheet, and further, without causing defects (peeling) in the seal as a molded product, It is an object of the present invention to provide a molding die structure that can be easily and reliably separated from a burr.
Furthermore, the seal that reliably maintain the sheet Lumpur function obtained, and an object thereof is to provide a seal manufacturing method can be easily separated a seal forming portion from (as burr) surface liner.

The molding die structure according to the present invention is a molding die structure having a pair of molds whose parting surfaces are superposed and separable from each other; to form a protrusion to form a connecting portion tapered burrs side, further, the stress concentration occurs for a V-notch to notch shape separation boundary portion tip and you connect the said tapered connecting portion of the small projections Each of the pair of molds has corners for forming, and the pair of molds further includes a plurality of cavities for molding a plurality of seal molding parts, and molding the burrs. A minute gap portion is formed between the parting surfaces of the pair of molds. At least one of the corners is a rectangular cross section Parts formed by, is obtained by a rush-like within the thickness dimension of the small gap.
Further, the seal manufacturing method according to the present invention is a seal manufacturing method using a pair of molds whose parting surfaces are superposed and separable from each other, and each of the pair of molds has a sealing function of a seal molding portion. A tapered small protrusion is formed in a portion that does not hinder, a tapered connecting portion is formed on the burr side, and a stress concentration generating V is formed at a separation boundary portion that connects the tip of the small protrusion and the tapered connecting portion. A corner portion for forming a notch in a notch shape, and the pair of molds further includes a plurality of cavities for forming a plurality of seal molding portions, and an enclosure for molding the burr A minute gap portion is provided between the parting surfaces of the pair of molds, and includes an annular space portion, and a minute gap portion for forming a planar liner that connects the plurality of burrs into a sheet shape. At least one of the parts Formed by a rectangular convex portion in a cross section and projecting into the thickness of the minute gap portion, and filling the cavity, the surrounding annular space portion and the minute gap portion of the pair of molds with raw rubber. Then, the sheet-shaped rubber molded product having the seal-molded portion, the burr, and the planar liner is vulcanized, and then the sheet-shaped rubber molded product is taken out from the pair of molds. In this method, the molded part and the burr are separated to produce a seal.

According to the molding die structure according to the present invention, it is possible to easily and efficiently separate from a burr and take out a seal molded product having a complicated cross-sectional shape without causing defects such as burrs.
Further, the seal manufacturing method according to the present invention can easily and efficiently separate and take out a seal molded product from a burr, and can provide a seal that is easy to manufacture and that reliably holds a sealing function. .

It is sectional drawing which shows one Embodiment of this invention. It is a principal part expanded sectional view of FIG. It is a principal part expanded sectional view which shows the high pressure clamping state which injection molding completed. It is a top view which shows an example of the sheet-like rubber molded product obtained by the shaping die structure of FIGS. FIG. 3 is an enlarged view of a main part of FIG. 2. It is the further enlarged view of the principal part of FIG. It is one principal part expanded sectional explanatory drawing of the rubber molded product (seal | sticker) obtained by the molding die structure which concerns on this invention. It is another principal part expanded sectional explanatory drawing of the rubber molded product (seal | sticker) obtained by the shaping die structure which concerns on this invention. It is a cross-sectional view illustrating an example of a sheet Lumpur. It is a principal part expanded sectional view for demonstrating the shaping die structure of a reference example. FIG. 11 is an enlarged cross-sectional explanatory view of a main part of a rubber molded product molded by the molding die structure shown in FIG. FIG. 12 is an explanatory cross-sectional view for explaining an action when separating the seal from the burr in the rubber molded product of FIG. It is a figure which shows an example of the seal | sticker manufactured from the metal mold | die structure of FIG. 10, Comprising: (A) is a perspective view, (B) is a principal part expanded sectional view.

Hereinafter, the present invention will be described in detail based on the illustrated embodiment.
As shown in FIG. 1 to FIG. 3 and FIG. 5, the parting surfaces P ₁ and P ₂ are provided with a pair of molds 1 and 2 that can be polymerized and separated from each other. The upper mold in the figure may be referred to as a first mold 1 and the lower mold in the figure may be referred to as a second mold 2 in some cases.

In the first mold 1 and the second mold 2, cavities 3 for forming a plurality of seal forming portions S ₀ as shown in FIG. ing.
1 to 3 exemplify a mold structure for injection molding. As shown in FIG. 1, a hot platen 8 is fixed to the upper surface of the first mold 1, and the second mold is used. A hot platen 9 is fixed to the lower surface of 2, and vulcanization is performed by heating and pressing after the injection molding step. An injection nozzle 22 is configured to inject and inject the raw rubber 5 in pressure contact with the sprue 6 at the center of the first mold 1 in plan view. The injected raw rubber 5 is formed in the 360 ° radial direction R from the position X where the axis of the sprue 6 intersects the parting P ₁ and P _{2 of} the first mold 1 and the second mold 2. It flows and fills the cavity sequentially in the radial outward direction.

FIG. 9A illustrates a seal S manufactured by the molding die structure according to the present invention, and specifically shows a U-packing. In the case of this U-packing, the outer lip portion 30, the bottom wall portion 31, the inner lip portion 32, and the dust seal protruding piece portion 33 are integrally formed, and the outer lip portion 30 has a triangular triangular cross section in the vicinity of the tip. A sealing projection 34 is formed. The inner diameter side corner portion 35 at the tip of the inner lip portion 32, the inner diameter side corner portion 36 at the tip of the projecting piece portion 33, and the sealing projection 34 exhibit an important sealing function as a U-packing (seal S). It is a part.
9B and 9C, the tapered small protrusions 37 and 38 indicated by dots are portions where the burrs 40 are separated (see FIGS. 7 and 8). That is, the small protrusions 37 and 38 have a tapered cross-sectional shape such as a triangle, and are provided at a position where the sealing function is not hindered by avoiding the aforementioned inner diameter side corners 35 and 36 and the protrusion 34, 7 (A) and FIG. 8 (A), from the state of being continuous (integrated) with the burr 40 through the tips of the tapered small protrusions 37 and 38, FIG. 7 (B) and FIG. as in B), are torn up from the tip of the small projections 37 and 38, burrs 40 are separated and removed from the seal mold section S _0.

More specifically, in the sheet-like rubber molded article 25 after vulcanization molding as shown in FIG. 4, the enlarged cross-sectional shape of the main part thereof is shown in FIGS. 7 (A) and 8 (A). As shown in the figure, V-shaped notches V ₁ and V ₂ for stress concentration generation are formed in both sides in a notch shape at the separation boundary portion 41 between the seal molding portion S ₀ and the burr 40. Tapered small protrusions 37 and 38 are formed at portions that do not hinder the sealing function of the seal S (see FIG. 9 (A)) taken out separately from the sheet-like rubber molded product 25 (see FIG. 4). On the other hand, a tapered connecting portion 40Z is formed on the burr 40 side, and the tips of the small protrusions 37 and 38 are connected to the tapered connecting portion 40Z on the burr 40 side, as shown in FIGS. In addition, V-shaped notches V ₁ and V ₂ are formed in the separation boundary portion 41 where tearing (cracks) easily occurs due to the occurrence of stress concentration.

That is, as shown in FIG. 6, the molding die structure according to the present invention includes _first corner portions 42, 43, 44, 45 for forming the stress concentration generating V-shaped notches V ₁ , V ₂ . A mold 1 and a second mold 2 are provided.
Further, in order to form a plurality of seal molding portions S ₀ as shown in FIG. 4 in the first mold 1 and the second mold 2, a plurality of cavities 3 are provided as shown in FIGS. It is provided in the form of a divergent spot in plan view. Moreover, as shown in FIG. 5, the parting lines L ₁ and L ₂ are shifted (two lines). That is, the seal S to be molded is a seal having a relatively complicated cross section such as U packing, and it is necessary to manufacture the mold by shifting the parting lines L ₁ and L ₂ in terms of shape.

The burr 40 shown in FIG. 8 has a disc shape, and the outer peripheral edge thereof is gradually thinned to form the aforementioned tapered connecting portion 40Z. Therefore, as shown in FIG. 5 and the like, the disk-shaped space 46 is formed by the first mold 1 and the second mold 2. Further, the burr 40 shown in FIG. 7 has an annular shape in plan view, the lower surface is a flat surface, the upper surface is a mirror-like shape, and the inner peripheral edge is gradually thinned to form the tapered connecting portion 40Z. . Therefore, as the mold structure, the surrounding annular space 47 is formed as shown in FIG.
Moreover, the plurality of burrs 40 (see FIG. 7) formed by the surrounding annular space 47 are connected to each other by a planar liner 48 as shown in FIG. (However, in FIG. 4, the burr 40 surrounding the outer periphery of the seal molding portion S _{0 in} an annular shape is not shown.)

As shown in FIGS. 5 and 2, the mold structure is such that the minute gap g forming the planar liner 48 (see FIG. 4) is parting surfaces P ₁ and P _{2 of a} pair of molds ₁ and _2. Are formed between each other. Furthermore, as shown in FIGS. 6A and 6B, at least one of the corners 42, 43, 44, 45 for forming the V-shaped notches V ₁ and V ₂ in a notch shape is: It is formed by a convex section 50 having a transverse cross section. In other words, specifically, one corner 42 is constituted by one corner of the rectangular convex portion 50.
Moreover, as shown in FIG. 6, the rectangular cross-section convex portion 50 rushes into the thickness dimension of the minute gap portion g. That is, the corner portion 42 also has a protruding shape within the thickness dimension of the minute gap portion 8. In the sheet-like rubber molded product 25 molded by such a mold structure, the position of the planar liner 48 having a thickness dimension g ′ equal to the thickness dimension of the minute gap g is shown in FIG. Shown with a two-dot chain line.

The thickness dimension g ′ may vary greatly. For example, in the mold structure having the _two parting lines L ₁ and L ₂ shown in FIG. 5, the thickness dimension g ′ varies greatly. . However, in FIG. 7A, when the wall thickness g ′ is increased, the V-shaped notches V ₁ and V ₂ are still kept in close proximity, and the burr 40 and the seal molding portion S ₀ are When an external force is applied to separate the burrs 40, a large concentrated stress is generated at the V-shaped notches V ₁ and V ₂ , so that the burr 40 and the seal molding portion S ₀ can be separated smoothly and reliably.

In other words, the seal separation operation can be reliably performed without causing a chipped portion or the like, a tear crack, or the like in the seal S itself.
The wall thickness g ′ of the planar liner 48 is preferably 0.05 mm to 0.15 mm, and particularly preferably 0.07 mm to 0.12 mm. The thickness dimension g'By setting in this way, even undercutting product, and a planar liner 48 and the seal forming portion S ₀ and burr 40 integral with the sheet, the dies 1 and 2 Can be taken out.

  By the way, in embodiment shown in FIGS. 1-3, etc., it was the metal mold | die structure applied to an injection molding method, However, This is also free to apply to a compression molding method. In the sheet-like rubber molded product 25 shown in FIG. 4, 28 is a thick (bar) outer frame burr formed along the outer peripheral edge, and the outer peripheral edge of the planar liner 48. Are connected (integrated). And this outer frame burr | flash part 28 is made into the space part 27 of the cross-sectional circular shape which consists of the concave grooves 29 and 29 of the cross-sectional semicircle shown in FIGS. 1-5 by the raw rubber which flows in, as shown in FIG. ,It is formed.

  Next, FIGS. 10 to 12 show a molding die structure as a reference example. FIG. 13 exemplifies a seal S formed by this mold structure. Specifically, the seal S is used for a reciprocating motion which is used by being attached to one annular concave groove of a sliding member which can slide axially with respect to each other. This is a seal S. The cross section has a triangular top portion 11, a rectangular body portion 12, and a groove bottom side bulging portion 13. Also, a plurality of small protrusions 17 are provided on the front surface and the back surface of the body portion 12 and are inserted so that the bulging portion 13 is in contact with the bottom surface of the annular groove (not shown). The top 11 is slidably contacted with the mating sliding member to form a sealing action. In addition, the small protrusion 17 can contact the side surface of the annular concave groove to prevent the body portion 12 and the top portion 11 from falling sideways.

FIG. 10 shows a mold structure for molding the seal S as shown in FIG. 13 and includes a pair of molds 1 and ₂ whose parting surfaces P ₁ and P ₂ are superposed and separable from each other. If the pair of molds 1 and 2 is called a first mold and a second mold, respectively, a plurality of seal molding parts S ₀ are shown in FIG. 4 (as in the above-described embodiment). As described above, the plurality of cavities 3 are arranged in a lattice shape in a plan view so that they can be taken out in a sheet form. The raw rubber is injection-molded and then vulcanized, etc., is the same as in the above-described embodiment. Compared with FIGS. 1 to 3, except for the first mold 1 and the second mold 2, The same configuration is used.

FIGS. 10B and 10C are enlarged views of portions b and c in FIG. 10A, respectively. As shown in FIGS. 10A, 10B, and 10C, as shown in FIG. One line L ₁ is provided, and further, an inner peripheral space 14 and an outer peripheral space 15 are provided in an annular shape near the inner periphery and the outer periphery of the annular cavity 3. The inner peripheral space portion 14 is formed by sub-grooves 14A and 14A that are recessed in the parting surfaces P ₁ and P ₂ of the first mold 1 and the second mold 2, and the outer peripheral space portion 15 is The sub-grooves 15A and 15A are formed in the parting surfaces P ₁ and P ₂ of the first mold 1 and the second mold 2, respectively.

The cavity 3 and the inner circumferential space portion 14 are connected to each other via a small film-shaped communication passage 16A, and the cavity 3 and the outer circumferential space portion 15 are connected to each other via a small-width film communication passage 16B. Are connected in communication. In FIG. 10A, the cross-sectional area of the inner circumferential side space portion 14 is sufficiently smaller than the sectional area of the cavity 3, and the inner peripheral edge of the inner circumferential side space portion 14 has a minute gap portion g that is circular in plan view. Are connected to each other, and in the seal molding portion S ₀ shown in FIG. 11 (A), the inner peripheral burr 40A formed in the inner peripheral space portion 14 is a minute gap portion g having a circular shape in plan view. Are connected to the disk-shaped sheet portion 18 formed by the above-described process, thereby forming an overall disk-shaped burr 40C.
On the other hand, the cross-sectional area of the outer peripheral side space portion 15 connected through the film-shaped communication path 16B having a small width is sufficiently smaller than the cross-sectional area of the cavity 3, and the outer peripheral edge of the outer peripheral side space portion 15 is The outer peripheral side formed by a large number of outer peripheral side space portions 15 connected to the minute gap portion g (see the right end of FIG. 10A) for forming the planar liner 48 described in FIG. The total number of burrs 40B (see FIG. 11A) can be separated and removed into a sheet form integrally with the planar liner 48.

Then, as shown in FIG. 10, the film-like communicating path 16A, the blade width W ₁ of the first mold 1 to form a 16B, the second mold 2 and the blade edge width W _2, are made different. In FIG. 10, W ₁ > W ₂ is set. For example, W ₁ is set to 0.01 mm and W ₂ is set to 0.03 mm. However, in order to prevent a step from being generated on the inner surface of the cavity 3, steps are formed in the sub-grooves 14A and 14A; the sub-grooves 15A and 15A.

An enlarged view of the main part of the rubber molded product 25 molded with the mold structure shown in FIG. 10 is shown as FIG. 11, and a further enlarged view is shown in FIG. As shown in FIG. 11 and FIG. 12, a seal forming portion S _0, burrs 40A, in each boundary portion between 40B is slightly W ₁ corresponding to the edge width W _1, W ₂ which are different, significantly W ₂ Separation thin portions 19 are formed on the upper and lower surfaces. However, in the seal molding portion S ₀ , the separation boundary portion has a continuous surface shape with no step, and has a step on the burrs 40A and 40B side (see FIGS. 12A and 12B).
Thereafter, the seal forming portion S ₀ is fixed and held, burrs 40A, the 40B, by applying an external force in the direction of arrow F, separated and removed burrs 40A, the 40B, to obtain a seal S as shown in FIG. 13 .

The direction of the arrow F in Bali 40A, when applying an external force to 40B, although the separation thin portion 19 resulting in elastically deformed upward convex shape, the upper surface 19A is narrow W _1, the direction extending from the lower surface 19B is substantially W ₂ Since it is difficult to elastically deform, a large tearing force due to the stress concentration occurs at the V-shaped notch V ₃ or V ₄ and tears in the directions of arrows G ₃ and G ₄ . In particular, since the crack in the direction of arrow G ₃ generated from the V-shaped notch V ₃ on the seal molding portion S ₀ side does not go to the seal S side but always goes to the thin-walled portion 19, the seal S is damaged such as tearing or tearing. The burrs 40A and 40B are beautifully separated without causing any problems. Note that even in the cases shown in FIGS. 10 to 13, the present invention is not limited to the injection molding method but can be applied to the compression molding method.

As described above, according to the present invention, in the molding die structure including the pair of dies 1 and ₂ whose parting surfaces P ₁ and P ₂ are superposed and separated from each other, the seal of the seal molding portion S ₀ is provided. The tapered small protrusions 37 and 38 are formed in a portion that does not inhibit the function, and the tapered connecting portion 40Z is formed on the burr 40 side. Further, the tip of the small protrusions 37 and 38 and the tapered connecting portion 40Z are connected to each other. Each of the pair of molds 1 and 2 is provided with corner portions 42, 43, 44, 45 for forming stress concentration generating V-shaped notches V ₁ , V ₂ in a notch shape in the separation boundary portion 41 to be connected. Since it has a configuration, the V-shaped notches V ₁ and V ₂ can be reliably and easily formed, and the seal S is a beautiful seal that is free from defects and cracks, and that completely maintains the sealing function. Can be manufactured.

Further, according to the present invention, the pair of molds 1 and 2 includes a plurality of cavities 3 for forming a plurality of seal forming portions S ₀ and an surrounding annular space portion 47 for forming the burr 40. In addition, a minute gap portion g for forming the planar liner 48 that connects the plurality of burrs 40 in a sheet shape is formed between the parting surfaces P ₁ and P ₂ of the pair of molds 12. Further, at least one of the corner portions 42, 43, 44, 45 is formed by a rectangular cross-section convex portion 50, and has a shape that protrudes into the thickness dimension of the minute gap portion g. The rubber molded product can be efficiently removed from the mold, and the seal can be easily separated from the sheet-like rubber molded product. Furthermore, the seal S having a complicated cross-sectional shape having _two parting lines L ₁ and L ₂ can be efficiently and beautifully manufactured.

Further, shea Lumpur, in tapered small projections 37, 38 which has been projected at a site sealing function is not inhibited, since burrs 40 is separated and removed, high quality sealing performance is always stably secured It is easy to manufacture.

1 (first) mold 2 (second) mold 3 cavity
5 raw rubber
37 Tapered small protrusion
38 Tapered small protrusion
40 Bali
40Z Tapered connection
41 Separation boundary
42, 43, 44, 45 Corner
47 Surrounding annular space
48 sheet liner
50 a rectangular cross section protrusion g minute gap portion P _1, P ₂ parting surface S ₀ seal mold section S seal V _1, V ₂ V-shaped notch

Claims (2)

In a molding die structure having a pair of molds (1) and (2) whose parting surfaces (P ₁ ) and (P ₂ ) are separable from each other,
A site that does not inhibit the sealing function of the seal forming portion (S _0), to form a tapered small projections (37) (38) to form connecting section tapered burrs (40) side (40Z), further, It said small projections (37) tip and the tapered connecting portion (38) (40Z) and stress concentration occurs for a V-notch that concatenates separation boundary portion (41) to (V ₁₎ (V ₂₎ a notch shaped Each of the pair of molds (1) and (2) includes corners (42), (43), (44), and (45) for forming the
Further, the pair of molds (1) and (2 ) are provided with a plurality of cavities (3) for molding a plurality of seal molding portions (S ₀ ) and an annular ring for molding the burr (40). A minute gap portion (g) for forming a planar liner (48) that includes a space portion (47) and connects the plurality of burrs (40) in a sheet shape is the pair of molds (1) (2). Are formed between the parting surfaces (P ₁ ) and (P ₂ ), and at least one of the corners (42), (43), (44), and (45) 50) and a molding die structure characterized in that it is formed into a protruding shape within the thickness dimension of the minute gap (g) . Parting surface (P ₁  ) (P ₂  ) Is a seal manufacturing method using a pair of molds (1) and (2) that can be separated from each other,
Each of the pair of molds (1) and (2) includes a seal molding portion (S ₀  ) Is formed in a portion that does not hinder the sealing function, and a tapered connecting portion (40Z) is formed on the burr (40) side, and the small protrusion (37) ( 38) V-shaped notch for generating stress concentration (V) at the separation boundary part (41) connecting the tip of the tapered connection part (40Z) ₁  ) (V ₂  ) Are formed in a notch shape, and the pair of molds (1) and (2) includes a plurality of seal molding portions ( S ₀  And a plurality of cavities (3) for forming the burr (40), a surrounding annular space (47) for forming the burr (40), and a surface connecting the plurality of burrs (40) in a sheet shape. The minute gap (g) for molding the liner (48) is the parting surface (P) of the pair of dies (1) and (2). ₁  ) (P ₂  ), And at least one of the corners (42), (43), (44), and (45) is formed by a rectangular cross section (50) in cross section, and the minute gap ( g) is rushed into the thickness dimension,
The cavity (3), the enclosed annular space (47), and the minute gap (g) of the pair of molds (1) (2) are filled with raw rubber (5), and the seal molding part (S ₀  ), The burrs (40), and the sheet-like rubber molded article (25) having the planar liner (48) are vulcanized and molded, and then the pair of molds (1) and (2) are used to form the sheet. The rubber molded product (25) is taken out, and then the seal molding part (S ₀  ) And the burr (40) are separated to produce a seal (S).

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