JP2015048681A - Striker and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-strength striker that achieves miniaturization and weight saving by making the thickness of an engagement rod as small as possible by increasing tensile strength of the engagement rod.SOLUTION: A striker 1 comprises a base plate 2 that is fixed to a mounting surface of a vehicle, and an approximately U-shaped engagement rod 3 that has both ends fixed to the base plate 2. The engagement rod 3 is made of austenite stainless steel.

Description

  The present invention relates to a striker for an opening / closing body for an automobile, and more particularly to a striker with improved strength and a method for manufacturing the same.

A striker for an opening / closing body for an automobile is composed of a base plate and a U-shaped engagement rod whose both ends are fixed to the base plate. In a striker applied to a side door of an automobile, a door latch device provided on the side door Generally, it is attached to the vehicle body side so that the engagement rod can be engaged with the latch.
A striker applied to a side door of an automobile is required to have high strength so that the side door does not open due to a side collision or the like. This is because if the striker strength is insufficient, the side door is deformed due to a side collision or the like, and when an excessive tensile load is applied to the engagement rod engaged with the latch, the engagement rod and the base plate This is because the door may open due to breakage or the caulking portion of the engagement rod disengaging from the base plate, releasing the engagement between the latch and the striker.

In view of such circumstances, for example, Patent Document 1 discloses that a base portion that is fixed to the base plate in the engagement rod is a large-diameter reinforcing portion having a larger diameter than other portions, thereby improving the strength. A striker is disclosed.
In Patent Document 2, an engagement rod (loop) is obtained by heat-treating a high-strength steel material such as chromium molybdenum steel, and the engagement rod is attached to a base plate made of a general steel material such as a hot-rolled steel plate. A striker having improved strength by fixing with cold caulking is disclosed.

JP 2002-201830 A Japanese Patent No. 2935812

For strikers applied to side doors of automobiles, in order to maintain the engagement with the latch even in the event of a side collision, etc. Strength that can withstand the tensile load is required.
Since the striker described in Patent Document 1 has a large-diameter reinforcing portion at the base portion fixed to the base plate of the engagement rod, the tensile strength and bending strength of that portion, and the strength of the caulking portion to the base plate are as follows. Become big. However, since the diameter of the portion other than the root portion is small, the strength of the portion may be insufficient depending on the material, and the above requirement may not be satisfied.
In order to achieve a striker that satisfies the above requirements, the diameter of the entire engagement rod may be increased. However, this increases the size of the striker and increases the mass, while engaging the engagement rod. There is also a problem that the door latch device including the latch to be enlarged is also enlarged.

On the other hand, in the case where the engagement rod is heat-treated on a high-strength steel material such as chromium molybdenum steel, as in the striker described in Patent Document 2, the strength is higher than that formed by a general steel material. However, there are also the following problems.
As described above, in order to obtain the strength that can withstand the tensile load in the lateral direction specified in the standards related to automobiles, it is necessary to increase the diameter of the engagement rod to some extent (for example, 8 mm). If the engagement rod diameter is not increased to some extent, when an excessive tensile load is applied to the engagement rod, the engagement rod will break at the U-shaped bent portion where stress is likely to concentrate, or the engagement rod The caulking portion may be plastically deformed and detached from the base plate due to a lateral tensile load applied to the base plate.

  Therefore, even in a striker made by heat-treating a high-strength steel material such as chromium molybdenum steel, it is necessary to increase the diameter of the engagement rod to some extent in order to obtain the tensile strength that satisfies the above requirements. Increasing the diameter of the engagement rod is not preferable in the present situation where further reduction in size and weight of the striker and the door latch device is required.

  In view of the above-mentioned problems, the present invention makes it possible to reduce the diameter of the engagement rod as much as possible by increasing the tensile strength of the engagement rod, to reduce the size and weight, and to provide a striker with high strength and a method for manufacturing the striker. It is intended to provide.

According to the present invention, the above problems are solved by the following inventions.
According to a first aspect of the present invention, there is provided a striker including a base plate fixed to a mounting surface of a vehicle and a substantially U-shaped engagement rod having both ends fixed to the base plate. The engagement rod is made of austenitic stainless steel. It is characterized by comprising.

  According to a second aspect of the present invention, there is provided a striker including a base plate fixed to a mounting surface of a vehicle and a substantially U-shaped engagement rod having both ends fixed to the base plate, wherein the engagement rod is a transformation of residual austenite. It is characterized by the fact that TRIP steel with induced plasticity is formed by bending it into a nearly U shape.

  According to a third invention, in the second invention, the TRIP steel is an austenitic stainless steel.

  According to a fourth invention, in the first or third invention, the austenitic stainless steel is SUS304 in JIS.

  According to a fifth invention, in any one of the first to fourth inventions, the base plate is formed of ordinary steel.

  A sixth invention is characterized in that, in any one of the first to fifth inventions, both end portions of the engagement rod are fixed to the base plate by hot caulking or cold caulking.

  According to a seventh invention, in any one of the first to sixth inventions, a fixing portion to which both end portions of the engagement rod in the base plate are fixed is bent so as to be separated from the mounting surface, It is characterized in that a deformation permissible space that continuously opens in both directions is formed between a mounting surface and the fixing portion on a line connecting both end portions of the engagement rod.

  An eighth invention is a striker manufacturing method comprising a base plate fixed to a mounting surface of a vehicle, and a substantially U-shaped engagement rod having both ends fixed to the base plate, wherein the base plate is made of ordinary steel. Forming a rod-shaped rod of a predetermined length by a rod-shaped material made of TRIP steel having transformation-induced plasticity of retained austenite, and plastically deforming the rod-shaped rod into a substantially U shape, The method includes a step of forming a U-shaped engagement rod and a step of fixing both end portions of the engagement rod to the base plate.

  The ninth invention is characterized in that, in the eighth invention, both end portions of the engagement rod are fixed to the base plate by hot caulking or cold caulking.

According to the striker of the present invention, as the stress concentration portion is deformed by the tensile load acting on the engagement rod, it transforms into a hard martensite phase due to the transformation-induced plastic effect of retained austenite. And toughness is increased. As a result, the diameter of the engagement rod can be reduced, and the striker can be reduced in size and weight.
Moreover, according to the striker manufacturing method of the present invention, a striker with improved tensile strength and toughness of the engagement rod can be easily manufactured.

It is a perspective view of one Example of the striker which concerns on this invention. Similarly, it is a top view of a striker. It is the III-III line longitudinal cross-sectional view of FIG. Similarly, it is a side view of a striker. It is process drawing which shows embodiment of the manufacturing method of the striker which concerns on this invention. It is the schematic which shows the damage state of the striker at the time of a tension test. It is the schematic which shows a broken state when a conventional striker is subjected to a tensile test.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 show a striker applied to a side door of an automobile according to the present invention. The striker 1 includes a base plate 2 fixed to an attachment surface D of a vehicle body of an automobile and a door latch device attached to the door. The engagement rod 3 is substantially U-shaped and can be engaged with a latch (not shown). The lower ends of the pair of leg portions 31, 31 in the engagement rod 3 are fixed to the base plate 2 by caulking. ing.

  The base plate 2 is made of plain steel such as a hot-rolled steel plate having a predetermined thickness so as to have a substantially elliptical shape in plan view, and the central portion on the short diameter side, which is the fixing portion of the both leg portions 31 of the engagement rod 3, By bending upward so as to form a substantially downward U-shape, it is continuous in both the left and right directions between the upward bent portion 21 and the mounting surface D on the line connecting both end portions of both leg portions 31. Thus, a deformable space S that opens is formed (see FIGS. 3 and 4). At both ends of the short diameter side of the base plate 2, that is, at both ends of the bent portion 21, leg fixing holes 4, 4 for fitting and fixing the lower ends of both legs 31 are fixed. Attachment holes 5 and 5 into which countersunk screws (not shown) for fixing to the attachment surface D are inserted are formed in both ends on the long diameter side.

  The engagement rod 3 is made of low alloy TRIP steel having transformation induced plasticity (TRIP) of retained austenite, for example, SUS304 in JIS which is a relatively inexpensive and metastable austenitic stainless steel. That is, as will be described later, a rod-shaped rod made of SUS304 is formed by bending it into a substantially U shape by pressing or the like. Stainless steel made of SUS304 in JIS corresponds to the international standard (ISO): TS15510L-No6.

Next, the manufacturing method of the striker 1 will be described with reference to the process diagram shown in FIG.
As shown in FIG. 5A, first, a rod-shaped rod 6 made of SUS304 is cut into a predetermined length to form a rod-shaped rod 6. The dimension of the rod-shaped rod 6 is a dimension obtained by adding the length shortened by caulking to the length of the engagement rod 3 described above. The rod-shaped material may be a material having a non-circular cross section such as an ellipse in addition to the circular cross section.

Next, as shown in FIG. 5B, the rod-shaped rod 6 is plastically deformed into a substantially U shape by pressing or the like, thereby forming the engagement rod 3 bent into a substantially U shape. As described above, when the rod-like rod 6 is plastically deformed into a U shape by pressing or the like, one of the retained austenite of the bent portions 32 and 32 of the engagement rod 3 is caused by the transformation-induced plastic effect of the retained austenite contained in SUS304. The portion is transformed into hard martensite, and the tensile strength of the portion is increased. However, since a part of the austenite phase of the bent portion 32 remains, the bent portion 32 also has ductility.
In addition, as shown in FIG.5 (c), the large diameter collar parts 33 and 33 required for a crimping process are cooled to the lower end part of the leg parts 31 and 31 in the engagement rod 3 bent in the U shape. You may form beforehand by the header process etc. between.

  Next, as shown in FIG. 5 (d), the lower end portions of the legs 31, 31 of the engagement rod 3 are made of the base plate 2 having the same shape as that described above, which has been manufactured in advance using ordinary steel such as hot rolled steel. The large-diameter flange portion 33 and the enlarged-diameter flange portion 34 are formed by fitting into the portion fixing holes 4 and 4 and hot crimping the upper and lower portions penetrating from the leg fixing holes 4 in the both leg portions 31. Note that when the large-diameter flange portion 33 is formed in advance in the step of FIG. 5C, only the enlarged-diameter flange portion 34 may be hot crimped. Thereby, the striker 1 as shown in FIGS. 1-4 is manufactured. The caulking operation is preferably performed by hot caulking as described above, but may be performed by cold caulking.

As described above, in the striker 1 of the above embodiment, the engagement rod 3 is made of low alloy TRIP steel having transformation-induced plasticity of retained austenite, that is, SUS304 in JIS which is austenitic stainless steel, and Although the bent portions 32 and 32 of the engagement rod 3 are partly transformed into a hard martensite phase by the transformation-induced plasticity effect of the retained austenite by being bent into a U-shape by pressing or the like. Since part austenite remains, the tensile strength and toughness of the engagement rod 3 increase.
Moreover, according to the striker manufacturing method of the above-described embodiment, the striker 1 with enhanced tensile strength and toughness of the engagement rod 3 can be easily manufactured.

  FIG. 6 and FIG. 7 show schematic views when the striker of the above embodiment and a conventional striker formed by subjecting the engagement rod 50 to chrome molybdenum steel by heat treatment are subjected to a tensile test. In addition, both the base plate 2 of this embodiment and the conventional base plate 60 shall consist of hot-rolled steel plates. Further, in the base plate 60 of the conventional striker, the deformation allowable space that opens continuously in both the left and right directions as in the present embodiment, such that both end portions of the fixing portion of the engagement rod 50 abut on the mounting surface D. It was fixed so that S was not formed.

  Comparing the results of the tensile test, the engagement rod 50 of the conventional striker breaks with the bent portion on the opposite side to the tensile direction constricted, whereas the engagement rod 3 of this embodiment has the engagement rod 3 on the tensile direction side. An intermediate portion of the leg portion 31 is constricted and broken.

  As described above, the engagement rod 3 formed of SUS 304 has a high tensile strength because, as described above, the bent portion 32 bent in a substantially U shape by pressing or the like induces transformation of residual austenite. Due to the plastic effect, part of the material transforms into a hard martensite phase, and as the plastic deformation of the engagement rod 3 proceeds, the transformation of retained austenite to martensite progresses gradually around the periphery. This is probably because the toughness (ductility) of the entire engagement rod 3 is increased.

  Further, a general striker including the above-described conventional striker often breaks at the bent portion 32 of the engagement rod where stress tends to concentrate, whereas in the striker of the above embodiment, the engagement rod 3 The intermediate part of the leg part 31 is gradually constricted and ruptured. This is because after the austenite phase remains in a part of the bent part 32, high ductility is exhibited along with the deformation of the stress concentration part. It is considered that the bent portion 32 of the engagement rod 3 has ductility in the tensile load direction by transforming into martensite.

Further, the engagement rod 3 has a high tensile strength because the shape of the base plate 2, that is, the center portion of the short diameter side which is the fixing portion of the both legs 31 of the engagement rod 3 in the base plate 2 is bent upward. In addition, a deformation-allowing space S that continuously opens in both the left and right directions is formed between the upward bent portion 21 and the mounting surface D on the line connecting both end portions of both leg portions 31. Is attributed.
When such a deformation allowable space S is formed, as shown in FIG. 6, when a tensile load in the direction of the arrow acts on the engagement rod 3, the base plate 2 crushes the deformation allowable space S and moves downward. In accordance with this, the deformation of the entire base plate 2 is promoted. As a result, coupled with the high ductility of TRIP steel, the tensile stress acting on the engagement rod 3 is further relaxed, and the engagement rod 3 is less likely to break. On the other hand, when both end portions of the fixing portion of the engagement rod 50 are brought into contact with the mounting surface D as in the conventional striker base plate 60 shown in FIG. 7, the base plate 60 on the tensile direction side is not easily deformed downward. Therefore, a large tensile stress acts on the engagement rod 50.

  When the engaging rod 3 is fixed to the base plate 2 by hot caulking, in the vicinity of the caulking portion including the enlarged diameter flange portion 34, the transformation of residual austenite to martensite is progressed as plastic deformation proceeds due to the tensile load. Since it progresses and the toughness increases, there is no possibility that the engagement rod 3 breaks at the caulking portion or the enlarged diameter flange portion 34 comes out of the leg fixing hole 4 of the base plate 2 as shown in FIG.

  As described above, according to the striker and the manufacturing method thereof according to the above embodiment, higher strength and toughness than the conventional striker can be obtained, so that the diameter of the engagement rod 3 can be reduced. As a result, the striker 1 and the door latch device engaged therewith can be reduced in size and weight.

As mentioned above, although this invention was described about embodiment, this invention can perform the following deformation | transformation and change with respect to said embodiment within the range which does not deviate from the summary.
In the above embodiment, the engagement rod 3 is formed of TRIP steel having transformation-induced plasticity of retained austenite, that is, SUS304 which is a relatively inexpensive metastable austenitic stainless steel. You may form by SUS301L in JIS which is steel, SUS310S in JIS which is stable austenitic stainless steel, etc.

  Moreover, in the said embodiment, although the base plate 2 was formed with the hot rolled steel plate which is plain steel, you may form with a cold rolled steel plate, a galvanized steel plate, etc., for example.

  Further, the method for processing the engagement rod 3 may be any of cold, warm, and hot pressing as long as austenite can remain in the bent portion 32.

  The striker according to the present invention can be applied to strikers such as the outside of the side door, a back door, a hood, a trunk lid, and the like.

Reference Signs List 1 striker 2 base plate 3 engagement rod 4 leg fixing hole 5 mounting hole 6 rod-shaped rod 21 upward bent part 31 leg part 32 bent part 33 large diameter collar part 34 enlarged diameter collar part 50 engagement rod 60 base plate D attachment Surface S Deformable space

Claims (9)

In a striker comprising a base plate fixed to a mounting surface of a vehicle, and a substantially U-shaped engagement rod having both ends fixed to the base plate.
The striker, wherein the engagement rod is made of austenitic stainless steel. In a striker comprising a base plate fixed to a mounting surface of a vehicle, and a substantially U-shaped engagement rod having both ends fixed to the base plate.
The striker, wherein the engagement rod is formed by bending TRIP steel having transformation-induced plasticity of retained austenite into a substantially U-shape.   The striker according to claim 2, wherein the TRIP steel is an austenitic stainless steel.   The striker according to claim 1 or 3, wherein the austenitic stainless steel is SUS304 in JIS.   The striker according to any one of claims 1 to 4, wherein the base plate is made of ordinary steel.   The striker according to any one of claims 1 to 5, wherein both ends of the engagement rod are fixed to the base plate by hot caulking or cold caulking.   A fixing portion to which both ends of the engagement rod in the base plate are fixed is bent so as to be separated from the mounting surface, and both ends of the engaging rod are between the mounting surface and the fixing portion. The striker according to any one of claims 1 to 6, wherein a deformation permissible space that continuously opens in both directions is formed on a line connecting the two. A striker manufacturing method comprising: a base plate fixed to a mounting surface of a vehicle; and a substantially U-shaped engagement rod having both ends fixed to the base plate,
Forming the base plate from plain steel;
Forming a rod-shaped rod of a predetermined length by a rod-shaped material made of TRIP steel having transformation-induced plasticity of retained austenite;
Forming the substantially U-shaped engagement rod by plastically deforming the rod-shaped rod into an approximately U shape;
And a step of fixing both end portions of the engagement rod to the base plate.   9. The striker manufacturing method according to claim 8, wherein both end portions of the engagement rod are fixed to the base plate by hot caulking or cold caulking.

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