JPH06185623A - Bead forming die and metal gasket - Google Patents

Abstract

PURPOSE:To form curved surface extending portions on a bead part so as to eliminate any damage on a deck surface by providing a run off where respective bead forming surface peripheral edges are removed, on a bead forming die for press-forming projecting beads and step beads each of which has a semi-circular shaped cross section while pinching an elastic metal plate. CONSTITUTION:In a metal gasket to be interposed between deck surfaces of a cylinder head and a cylinder block of an internal combustion engine, projecting beads 1 each of which has a semi-circular shaped cross section are provided on the peripheral edges of combustion chamber holes drilled through an elastic metal plate 10, and step beads 2 are provided on the peripheral edges of a cooling water hole, bolt hole, etc. In a die for press-forming such a metal gasket, a run off 30 is formed by removing the peripheral edge of respective upper die base plates 22a, 25a so as to release the reaction as it is which is generated on the metal base plate 10 in a process of molding, and also generated upward on respective peripheral edges of lower base plates 22b, 25b. Moreover, the run off 30 is similarly formed on the forming portion of step beads 2, thereby curved surface extending portions 11a, 12a can be formed on respective beads 1, 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket inserted between the deck surfaces of a cylinder head and a cylinder block of an internal combustion engine, and particularly to a bead of a semicircular convex bead and a step bead formed on the metal gasket. The present invention relates to a bead molding die for improving a shape and a metal gasket obtained by the molding die.

[0002]

2. Description of the Related Art Conventionally, a metal gasket formed by forming a bead on an elastic metal plate is inserted between deck faces of a cylinder head and a cylinder block of an internal combustion engine, and the bead is elastically deformed by a bolt tightening force when the cylinder head is fastened. Then, the elastic restoring force at the time of this deformation forms a seal line on the deck surfaces to perform a seal between the deck surfaces and to follow the distortion of the deck surfaces to maintain the sealing effect.

[0003]

By the way, in order to form the semi-circular convex bead 1 or the step bead 2 shown in FIG. 5 (a), the mold shown in FIG. 5 (b) is used. You can

In the upper die of this mold, a support plate 24 is fixedly provided on the lower surface of the upper holder 21a, and further, from the combustion chamber hole forming side, via the stoppers 23a and 23b, with respect to the stoppers 23a and 23b, inside the convex bead circumference. The upper die substrate 22a for forming and the upper die substrate 25a for forming both beads are provided, and the stopper 2
3a and 23b are first formed with a portion 23a for supporting the upper mold substrate 22a for the inner circumference of the convex bead, and then the protruding member 2 is provided on the outer circumference thereof.
0 is protruded from the formation surface of both substrates 22a and 25a, and is fastened with a screw 20a. A stopper 23b for supporting both bead forming upper die substrates 25a is provided on the outer periphery thereof, and the step bead outer periphery is provided along the outer periphery thereof. Upper mold substrate 2
6a is fixed to the support plate 24. On the other hand, the lower die is formed on the upper surface of the lower holder 21b with a gap corresponding to the bead width L01 of the convex bead 1 from the combustion chamber hole forming side to the convex bead inner lower die base plate 22b and the outer side thereof. The lower die substrate 25b for the step bead is provided, and the lower die substrate 26b for the outer periphery of the step bead is disposed with a gap corresponding to the step bead width L02 being opened on the outer periphery thereof.

In this mold, the upper bead forming upper die substrate 22a and the bead forming upper die substrate 25a are held by bolts 28 via springs 29, and when not pressed, each upper die substrate 22a, The molding surface of 25a is at the same level as the molding surfaces of the step bead outer peripheral upper die substrate 26a and the projecting member 20, and the step bead outer peripheral lower die substrate 26b.
Similarly, it is held at the same level as the molding surface of the step bead inner lower die substrate 25b by being held by the bolt 28 via the spring 29. Therefore, at the time of press molding, first, the upper mold substrates 22a, 25a, 26a and the protruding member 20 are formed.
Then, since the metal substrate 10 is sandwiched between the lower mold substrates 22b, 25b, and 26b, and is pressed and held under the strong pressure of the elastic force of the spring 29, the wrinkle holding effect and the positioning effect are exhibited.

However, the bead formed by this conventional mold has a convex bead inner peripheral upper mold substrate 22a and both bead molding lower mold substrates 2 at the molding position of the convex bead 1.
Lower mold substrate 2 for convex bead inner circumference in which molding surfaces of 5a face each other
2b and the peripheral portions of both bead forming lower mold substrates 25b have a flat shape, there is no play for letting the reaction force of the pressing force escape to both hem portions of the convex bead 1, and the convex bead 1 Corners due to the pressing force are generated on the hem portions 11, 11. Also,
Similarly, in the molding part of the step bead 2, the upper and lower bead forming upper and lower mold substrates 25a and 25b and the step bead outer peripheral upper and lower mold substrates 26a and 26b have mutually opposing surfaces on the same line with a step bead width L02 therebetween. Therefore, there is no play for letting the reaction force of the pressing force escape to the bent portions 12, 12 of the step bead 2, and a corner portion is generated at the portion.

Therefore, when this metal gasket is inserted between the deck surfaces, 1) it is difficult to operate because the deck surface hits a corner when bolts are fastened, and 2) the deck surface is damaged at the time of operation. , 3) The bending stress of the metal plate itself becomes strong, which causes cracks. 4) The surface sealing material is partially cut due to excessive surface pressure,
Or, there were various problems of peeling. Further, in order to eliminate the corners of the convex beads 1 or the step beads 2, as shown in FIG. 5 (c), the convex bead inner peripheral lower die substrate 22b, the both bead forming lower die substrates 25b, the step bead outer peripheral upper die substrate 22b. When a curved surface r is formed at a corner of the mold substrate 26a or the like, the convex bead inner peripheral upper mold substrate 22a on the opposite surface, both bead molding upper mold substrates 25a,
Since the lower mold substrate 26b for the outer periphery of the step bead does not have a press along the curved surface r, it is not possible to eliminate the corners of the bead simply by widening the bead widths L01 and L02, and the molding surface is polished at the time of maintenance of the mold. Then, this molding surface is ground to a position as shown by a chain double-dashed line in the drawing, and the curved surface r
And the bead widths L01 and L02 change, causing a change in bead load.

[0008]

The present invention was made in order to solve the above problems, and the present invention will be described with reference to FIG. 1 corresponding to an embodiment. The bead molding die of the present invention will be described. Is a bead forming mold for sandwiching the elastic metal plate 10 with a member protruding from the opposing forming surface and a member having steps on the upper and lower forming surfaces to press and form the semi-circular convex bead 1 and the step bead 2, respectively. In order to form curved bead overhangs 11a, 12a by removing the peripheral edge of the molding surface located in the surface pressure urging direction of the ridge 11 of the semi-circular convex bead 1 and the bent portion 12 of the step bead 2. In the metal gasket, the semi-circular convex bead 1 and the step bead 2 are formed on the elastic metal plate 10 by this bead molding die. The foot of the mountain portion 11 and the step bead 2 of the bent portion 12 curved overhang 11a respectively face urge urging side with respect to a metal gasket formed of 12a are obtained.

[0009]

In the bead molding die of the present invention, the elastic metal plate is sandwiched between the member protruding from the opposing molding surface and the member having a step on the upper and lower molding surfaces, and the semi-circular convex bead 1 and the step bead respectively have a cross section. When press-molding 2, the crest 11 of the convex bead 1 having a semicircular cross-section and the bent part 12 of the step bead 2 have a relief 30 in which the peripheral edge of the molding surface corresponding to the surface pressure urging direction is removed. , Mountain hem of each bead 11
And the curved surface overhanging portion 11a in the surface pressure biasing direction of the bending portion 12,
12a is formed.

Due to such a bead shape, the curved surface overhanging portions 11a and 12a abutting on the deck surface have a curved surface shape, and the surface of the deck is not damaged even if surface pressure is applied. Further, in the present invention, the bead width L01
The bead height H01 may be unchanged (see FIGS. 2 and 5), and the respective ranges L21 and L22 and the sizes (radius of curvature) R1 and R2 of the curved surface overhanging portions 11a and 12a of the present invention may be changed. This makes it possible to change the total bead load on the bead line.

[0011]

EXAMPLES Examples of the present invention will be described below with reference to FIGS.

1 (a) and 1 (b) are cross-sectional views of a mold for molding the metal gasket of the present invention. 2A and 2B are views related to the metal gasket according to the present invention. FIG. 2A is a sectional view taken along the line AA of FIG. 4, FIG. 2B is a sectional view taken along the line QQ of FIG. 4, and FIG. FIG. 6 is a sectional view taken along line P-P in FIG. 4. Figure 3
It is a figure which shows the relationship of the load and deflection of the step bead corresponding to the PP cross section and QQ cross section of FIG. Figure 4
FIG. 3 is a partial perspective view of a metal gasket according to the present invention.

The mold of this embodiment is different from the conventional mold shown in FIG. 5 (b) in the following parts. That is, when the convex member 20 is pressed against the metal substrate 10 placed on the gap between the lower bead forming lower die substrate 22b and the bead forming lower die substrate 25b at the forming portion of the convex bead 1, Both lower mold substrates 22b and 25b formed on the metal substrate 10.
Of the lower bead substrates 22b and 25b and the upper mold substrate for forming bead moldings 22a facing the respective peripheral parts of the lower mold substrates 22b and 25b so that the reaction force generated upward at the peripheral parts of The relief portion 30 is formed by removing the peripheral portion of 25a. As a method of forming this escape portion 30, FIG.
As shown in FIG. 3, support plates 32a and 32b are provided below the stoppers 23a and 23b, respectively, and upper and lower molding members 31a and 31b are fastened with bolts 28 with a gap between the inner and outer circumferences of the projecting member 20. Thus, the relief portion 30 is formed, or the relief portion 30 is formed by notching the molding surface portion of the protruding bead inner lower die substrate 22a and the both bead molding lower die substrates 25a on the protruding member 20 side. good. If the relief portions having the width L21 are formed at the peripheral edge portions of the upper die substrates 22a and 25a on the protruding member 20 side by using such a die, the same width L21 as the relief portion is formed in the both skirt portions 11 of the convex bead 1. Only the curved surface protrusion 11a is formed.

Similarly, in the molding portion of the step bead 2, both bead molding lower mold substrates 25b and the step bead outer peripheral lower mold substrate 26b are opposed to above each bead molding upper mold substrate 25a and the step beads. An escape portion 30 having a width L02 is formed on each peripheral portion of the outer peripheral upper substrate 26a, and the bent portion 12 of the step bead 2 forms a curved surface protruding portion 12a having a width L02 in the surface pressure urging direction. .
The escape portion 30 of the step bead 2 is, for example, as shown in FIG.
Alternatively, the escape portion 30 may be formed by cutting out the peripheral edge portion.

Thus, a metal gasket (shown in FIG. 4) having the bead shape shown in FIG. 2 is obtained by the above mold.

In this metal gasket, for example, as the range of the curved surface overhanging portion 12a of the cooling water seal bead 2a on which the step bead 2 is formed approaches L22 (Q-Q cross section in FIG. ) To L23 (PP cross section in FIG. 1 (b)), the radius of curvature of the curved surface overhanging portions 11a and 12a is also increased from R2 to R3, and the spring constant is also bolted as shown in FIG. It is possible to make the deck surfaces evenly adhere to each other regardless of the difference in the bolt fastening force, by decreasing the cross section from the Q-Q cross section having a small pushing force to the PP cross section having a larger bolt fastening force. The bead sealing function can be improved.

[0017]

As described above, according to the bead molding die of the present invention, the curved surface overhanging portion is formed in the surface pressure urging direction of the ridge hem of the convex bead having a semicircular cross section and the bending portion of the step bead. .

In this metal gasket, since each curved surface overhang has a curved shape, the deck surface can be smoothly operated even if surface pressure is applied during bolt fastening, without damaging the deck surface.

Moreover, by adjusting the respective ranges of the curved surface overhanging portion of the present invention without changing the bead width and the bead height, the radius of curvature of the curved surface overhanging portion also changes, and the spring constant is changed to change the total bead load. Since it can be changed on the bead line, the bead sealing function is improved by eliminating partial overpressure on the bead, the cause of cracks is removed, and the cutting and peeling of the surface sealing material is prevented. can do.

[Brief description of drawings]

1 (a) and 1 (b) are cross-sectional views of a mold for molding a metal gasket of the present invention.

2 is a diagram relating to a metal gasket according to the present invention, FIG. 2 (a) is a sectional view taken along line AA of FIG. 4, FIG. 2 (b) is a sectional view taken along line QQ of FIG. 2 (c) is a sectional view taken along the line P-P in FIG.

FIG. 3 is a diagram showing a relationship between a load and a deflection of a step bead corresponding to the cross section taken along the line PP and the line QQ in FIG. 2.

FIG. 4 is a partial perspective view of a metal gasket according to the present invention.

5 is a diagram relating to a conventional metal gasket, FIG. 5 (a) is a cross-sectional view of a portion corresponding to a cross section taken along the line AA of FIG. 4, and FIG. 5 (b) is FIG. 5 (a). A cross-sectional view of a mold for molding the metal gasket of Fig. 5 (c) is a mold designed to eliminate the corner portion of the bead.

[Explanation of sign]

1 ... Semi-circular convex bead, 2 ... Step bead, 10 ...
Elastic metal plate, 11 ... Crest of semi-circular convex bead, 12
... curved portion of step bead, 11a ... curved protrusion of semi-circular convex bead ridge portion, 12a ... curved protrusion of bent portion of step bead, 30 ... relief portion.

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[Procedure amendment]

[Submission date] October 18, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

2 is a diagram relating to a metal gasket according to the present invention, which is a sectional view taken along the line AA of FIG. 4, a sectional view taken along the line QQ of FIG.
It is the PP sectional view taken on the line of FIG.

Claims (2)

[Claims] 1. A bead (1) and a step bead (1) each having a semicircular cross section and sandwiching an elastic metal plate (10) between a member projecting from an opposing molding surface and a member having a step on the upper and lower molding surfaces, respectively.
In a bead molding die for press-molding (2), a ridge hem (11) and a step bead of the semi-circular cross-section convex bead (1).
(2) is characterized in that the peripheral portion of the molding surface located in the surface pressure biasing direction of the bent portion 12 is removed to form the relief portion 30 for forming the curved surface overhanging portion (11a, 12a) of the bead. Mold for bead molding. 2. A convex bead (1) having a semicircular cross section on an elastic metal plate (10).
In the metal gasket having the step bead (2) and the convex bead (1) of the semi-circular convex bead (1) in cross section and the bent portion (12) of the step bead (2), respectively, the surface pressure urging side. A metal gasket characterized in that curved surface overhangs (11a, 12a) are formed on the metal gasket.