KR20170139862A - Manufacturing Method for Explosive tube of Pretensioner, Explosive tube and Pretensioner using thereof - Google Patents

Abstract

An objective of the present invention is to precisely and quickly manufacture a cylinder at an economic cost. To achieve this, a method to manufacture a cylinder used for a pretensioner of a seat belt of a vehicle using a hollow steel tube in a cylindrical shape with a predetermined diameter comprises: (a) a cutting step of cutting the tube to a predetermined length; (b) a bending step of bending a middle part of the tube; (c) a forming step of expanding a diameter of one end of the bent tube into a predetermined diameter, and axially fitting an end part with a thickness reduced by diameter expanding forming; and (d) a pressing step of removing a part of a cylindrical surface of the other end of the tube. A change in thickness of the tube is within 5% before and after the forming step, and the forming step fixates the tube in a mold and couples an outer diameter of the tube to an inner diameter of a diameter expanded tube.

Description

Technical Field [0001] The present invention relates to a method of manufacturing a cylinder of a pretensioner for a seat belt of a vehicle, and a cylinder and a pretensioner using the same. Technical Field [0001]

The present invention relates to a method of manufacturing a cylinder of a pretensioner for a seat belt of a vehicle, and a cylinder and a pretensioner using the same. More particularly, to a manufacturing method for precisely manufacturing a cylinder of a pretensioner at an economical price, a cylinder using the cylinder, and a pretensioner.

Generally, a seat belt installed in a vehicle restrains an occupant's upper body during a vehicle collision, thereby preventing secondary collision and reducing shock. The three-point seat belts, in combination with a shoulder belt for shoulder restraint and a lap belt for restraint, are currently the most common form, designed to prevent the occupant from jumping out of the vehicle in the event of a vehicle crash. Is mainly used.

This seat belt has a problem that the seat belt can not completely fix the passenger's body to the seat because of the acceleration at the time of collision of the vehicle.

In addition, such a seat belt is interlocked with an airbag system (SRS) to mitigate the impact on the occupant. At this time, the airbag has a considerable impact upon explosion, and a high temperature of 300 to 400 degrees is generated. Therefore, when the seat belt is loosely fixed to the occupant, there is a problem that the occupant is injured by the airbag.

In order to prevent such a problem, a pre-tensioner is used for the seat belt.

FIG. 1 is a schematic diagram showing the role of a pretensioner, and FIG. 2 is a conceptual diagram showing an operating state of the pretensioner.

As shown in Figs. 1 and 2, the pretensioner 1 is a device that instantaneously rewinds the seat belt 3 when a collision from the front of the vehicle is detected, thereby strongly restraining the occupant by the seat belt 3 . For example at a speed of about 50 km / h, within 18 ms of a frontal vehicle collision. The airbag 5 assists the seat belt 3 provided with such a pretensioner 1 to achieve optimal shock mitigation.

1, a conventional pretensioner 1 includes a cylinder 10 with a guide formed thereon, a plurality of balls 20 inserted into the guide of the cylinder 10, And a gear portion (30) provided as far as possible. The gear portion 30 includes an outer ring gear portion formed with gears on its inner and outer peripheral surfaces, and an inner ring gear portion formed with gears on its outer peripheral surface. An explosive member 40 is mounted on the lower end of the cylinder 10, and a pistol containing gunpowder is mounted on one side of the seat belt. When the gunpowder ignites due to the occurrence of the collision, the gas explodes and the ball 20 moves. As the ball 20 moves, the outer ring gear portion of the gear portion 30 rotates clockwise in the drawing When the driver or the occupant moves forward after the collision of the vehicle, the seat belt is pulled back to the seat side.

However, such a cylinder 10 needs to be bent at a right angle in the structure of a vehicle, but it is very difficult to bend it at a right angle of 90 占 and the method of manufacturing it by a mold is extremely difficult. It is a very difficult task, so it is a problem to make precise and economical production.

Patent No. 10-0412451 Patent No. 10-1261848

Accordingly, the present invention has been made to solve the above-described problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bending step for inserting a mandrel plug into a cutting step, a chamfering step, and an inner diameter for precisely and quickly manufacturing a cylinder of a pretensioner at an economical price, And a cylinder and a pretensioner using the same.

A first object of the present invention is to provide a method of manufacturing a cylinder used in a pretensioner for a seat belt of a vehicle using a hollow tube made of a steel cylinder having a specific diameter, A cutting step of cutting the tube to a specific length; b) a bending step of bending the break of the tube; c) a molding step of forming one end of the bent tube by a specific diameter and press-molding the end portion thinned by expansion to the axial direction; and d) a pressing step of removing some of the cylindrical surfaces of the other end of the tube, wherein a change in the thickness of the tube is within 5% before and after the forming step.

According to the present invention, the step (d) includes: a plug inserting step of inserting a plug having an outer diameter of the outer diameter of the tube to the inner surface of the tube and having an opening of a specific shape, at the other end of the tube; And a pressing step of pressing and removing a portion corresponding to the opening portion in the tube.

In the present invention, an open portion is provided at the other end of the tube, and the step d) includes a front press step of removing a part of the cylindrical surface of the tube to produce a front face of the open portion; And a side pressing step of removing a part of the cylindrical surface of the tube which has undergone the front-pressing step, thereby manufacturing the side surface of the opening part.

In the present invention, the forming step includes a first expanding step of expanding one end of the tube so as to have two ends; A second enrichment step of achieving a specific diameter of the tube that the user targeted, further extending the one end of the once-expanded tube; And an indentation step of press-pressing in the axial direction to thicken the thickness of one end of the tube that has been twice expanded.

Further, in the present invention, the forming step may include a press-fitting step of press-fitting in the axial direction to thicken one end of the tube; A first expanding step of expanding the one end of the tube after the indenting step to have two ends; And a second expelling step of achieving a specific diameter of the tube that the user targeted, further extending the one end of the once expanded tube.

In the present invention, the bending step is performed a plurality of times and bent at 90 degrees in the axial direction of the tube, and a mandrel can be inserted into the inner diameter of the tube to be bent.

A second object of the present invention is to provide a cylinder of a pretensioner for a seat belt of a vehicle which is manufactured through a hollow tube made of a steel material having a cylinder of a specific diameter and which is manufactured by expanding one end of the tube, ; A guide formed by bending the suspension of the tube, a plurality of balls arranged in a row inside the guide tube, and a ball moved by the high pressure gas generated by the explosion portion; And an opening in which one side of the other end of the tube is removed to be opened and in which a ball in the guide is reached by a high pressure gas when a high pressure gas is generated and an engaged portion of the reached ball and the pretensioner is engaged, Can be achieved by providing a cylinder of a pretensioner for a belt.

In the present invention, the difference between the thickness of the explosion portion and the thickness of the guide may be about 5% of the thickness of the guide.

In the present invention, the roundness of the inner diameter of the guide may be the same as the straight section of the bending portion, which is the bent portion.

A third object of the present invention is to provide a pretensioner for a seat belt of a vehicle, comprising: a belt spool on which a seat belt is wound; A gear portion connected to one side of the shaft of the belt spool and rotated integrally with the belt spool; And a cylinder having one end opened by tangential contact with the gear portion and an explosive member provided at the other end and having a ball movable along the guide therein so that the ball and the gear portion are engaged with each other at an open end, When the explosive member explodes and a high-pressure gas is generated in the cylinder, the ball reaches the gear portion by the high-pressure gas, the ball and the gear portion mutually engage so that the belt spool rotates about the shaft, And a pretensioner for a seat belt.

As described above, the present invention has the following effects.

First, according to one embodiment of the present invention, there is an effect that bending can be performed at a right angle of 90 ° while reducing the risk of explosion due to gunpowder in the production of a cylinder.

Second, according to one embodiment of the present invention, there is an effect that the thickness can be manufactured so as to be manufactured in the molding step.

Third, according to an embodiment of the present invention, it is possible to perform the pressing step in a simple and economical manner.

Fourthly, according to the embodiment of the present invention, the roundness of the bending portion is maintained.

Fifth, according to the embodiment of the present invention, the hollow tube can be bent regardless of the position, the hollow tube is fixed to the metal mold, Can be assembled quickly.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and, together with the description, And shall not be interpreted.
1 is a schematic diagram showing the role of a pretensioner,
Fig. 2 is a conceptual view showing an operating state of the pretensioner,
3 is a perspective view of a cylinder according to an embodiment of the present invention,
4 is a schematic flowchart showing a method of manufacturing a cylinder of a pretensioner for a seat belt of a vehicle according to an embodiment of the present invention;
FIG. 5 is a cross-sectional view illustrating a step of cutting a cylinder according to an embodiment of the present invention,
FIG. 6 is a cross-sectional view illustrating a chamfering step of a cylinder according to an embodiment of the present invention,
FIG. 7 illustrates a bending step of a cylinder according to an embodiment of the present invention,
FIG. 8 is a view illustrating a molding step of a cylinder according to an embodiment of the present invention,
FIG. 9 is a cross-sectional view illustrating a front press step of a cylinder according to an embodiment of the present invention,
10 is a side press step of a cylinder according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, the constituent elements are denoted by the same reference numerals, and a detailed description thereof will be omitted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following detailed description of the operation principle of the preferred embodiment of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may unnecessarily obscure the subject matter of the present invention.

The same reference numerals are used for portions having similar functions and functions throughout the drawings. Throughout the specification, when a part is connected to another part, it includes not only a case where it is directly connected but also a case where the other part is indirectly connected with another part in between. In addition, the inclusion of an element does not exclude other elements, but may include other elements, unless specifically stated otherwise.

1. Cylinder

3 is a perspective view of a cylinder according to an embodiment of the present invention, in relation to a cylinder according to an embodiment of the present invention.

3, the cylinder 10 according to an embodiment of the present invention includes a guide 20, which is a bushing with a U-shape so that a plurality of balls 20 can be inserted therein, . ≪ / RTI >

The guide 11 may be provided with an explosion part 12 through which an explosive member is inserted to generate a gas. The other end of the guide 11 is provided with a fastening hole 182 for fastening the cylinder 10 to the housing of the pretensioner. . The other end of the guide 11 may be provided with an opening 180 through which a part of the cylinder 10 is opened so that the gear portion of the pretensioner and the ball 20 are in contact with each other.

The explosion portion 12 may be formed with two ends, and it is preferable that the explosion portion 12 is formed to have a specific thickness or more in order to withstand an impact upon explosion of the explosion member. A portion of the outer side of the explosion portion 12 may be provided with a direction portion 120 that is chamfered in a plane and holds the direction of the cylinder 10.

The guide 11 extends from one side of the explosive 12 and includes a first bending portion 13, a first straight section 14, a second bending section 15, a second straight section 16, And may lead to an end portion 18 including a bending portion 17, a fastening hole 182 and an opening portion 180.

The first bending portion 13 may be connected to one side of the explosive portion 12 and connected to the first bending portion 13 bent at 90 degrees. The first bending portion 13 can extend into the first straight section 14 and the first straight section 14 extends perpendicular to the explosive section 12 and into the second bending section 15 . The second bending portion 15 may extend straight to the second straight line section 16 and the second straight line section 16 may be configured to be parallel to the explosive section 12. The second straight line section 16 may be connected to the third bending section 17 and the third bending section 17 may be bent at 90 degrees from the second straight line section 16. [ The third bending portion 17 extends to the end portion 18. That is, the end portion 18 may extend in the normal direction of one plane formed by the explosive portion 12, the first rectilinear section 14 and the second rectilinear section 16.

The end portion 18 is configured to contact with the gear portion 30 in a tangential direction. The ball 20 is moved by the explosion of the explosion member provided in the explosion portion 12 and the ball 20 to be moved is engaged with the outer ring gear portion at the opening portion 180. [ The outer ring gear unit is rotated in the direction in which the seat belt is pulled, whereby a pre-tention can be provided to the occupant in the event of a vehicle collision.

2. Cylinder making method

4, a method of manufacturing a cylinder of a seat belt pretensioner for a vehicle according to an embodiment of the present invention includes a cutting step S1, a bending step S2, a molding step S3, and a pressing step S4. .

2. (1) Cutting step (S1)

5 shows a step S1 of cutting a cylinder according to an embodiment of the present invention.

The manufacturer cuts the tube to the desired length. According to an embodiment of the present invention, the outer diameter of the tube may be 14 mm, the thickness may be 1.5 mm, and the inner diameter may be 11 mm.

The present invention may further include a chamfering step, as shown in Fig. 6, prior to the bending step S2.

The chamfering step is a step in which the end of the cut tube is chamfered to the desired dimension. According to one embodiment of the present invention, it is possible to chamfer with C0.5.

2. (2) Bending step (S2)

7 shows a bending step S2 of the cylinder 10 according to an embodiment of the present invention. In the bending step S2 according to an embodiment of the present invention, three portions can be bent. This may vary depending on the shape of the pretensioner. In an embodiment of the present invention, the first bending portion 13, the second bending portion 15, and the third bending portion 17 may bend 90 degrees. However, in the conventional bending step, the roundness is varied, and the ball 20 is caught in the manufactured cylinder 10.

The bending step S2 according to an embodiment of the present invention bends by inserting a mandrel plug into the inner diameter of the guide in order to maintain the roundness and to solve such a problem. By this method, the roundness of the inner diameter of the guide is maintained, and the effect that the ball 20 passes without being caught is generated, and the quality of the cylinder 10 is improved.

In addition, in the prior art, there is a problem that the molding step is carried out before the bending step, and the part where the bending step is formed is correctly positioned at the same position of the bending mold when the forming step is performed before the bending step .

This is because, due to the change of the position of the tube after the bending step, the tubes can not be assembled with the expanded inner diameter at the same position in the expansion process and the tube-to-tube assembly process.

The bending step S2 according to an embodiment of the present invention is performed before the forming step S3 to be described later. The bending of the tube is possible regardless of the position, the tube is fixed to the mold, The tube is molded in the same shape at the same position, and the tube can be quickly assembled to the tube inner diameter.

2. (3) Forming step (S3)

8 shows a forming step S3 of the cylinder 10 according to an embodiment of the present invention.

In the forming step S3, one end of the bent tube is subjected to tube forming with a specific diameter, and the end portion thinned by the expanding molding is press-formed in the axial direction.

The guide 11 and the explosion part 12 can be distinguished from each other by enlarging the end portion of the chamfered tube. The explosion portion 12 may be configured to have at least two inner diameters, and portions a and b may be expanded as shown in Fig. In the embodiment of the present invention, the length of the portion a is 21.2 mm and the length of the portion b is 9.6 mm.

According to an embodiment of the present invention, the forming step S3 may proceed to step 3.

The forming step S3 may include a first expanding step, a second expanding step, and an indenting step.

In the first expansion step, the ends of the tube 10 having an inner diameter of 11 mm can be expanded to have inner diameters of 12 mm and 15 mm, respectively. In the second expansion stage, it is finally possible to expand to 14mm and 17.2mm, respectively. At this time, in the case of the portion "b" having a height of 17.2 mm, the thickness is thinned from 1.5 mm to 1.3 mm. In the third step, the same outline design as the directional portion 120 of the explosive portion 12 is taken, and the press-in step is performed in the axial direction at the end portion in order to preserve the thinned thickness of the portion b. and the thickness of the portion b is maintained at 1.5 in the press-fitting step of the portion b, thereby improving the safety of the cylinder 10 manufactured.

Further, the forming step S3 may be carried out in the order of the indenting step, the first school step and the second school step.

The press-in step is press-fitted in the axial direction to secure the thickness of one end of the tube. The first expansion step expands one end of the tube to have two ends and achieves the diameter of the tube the manufacturer intended to further expand one end of the tube after completing the first expansion step.

The diameter of the tube 10 in the first expansion step and the diameter of the tube in the second expansion step are as described above.

2. (4) Pressing step (S4)

9 to 10 are views schematically showing the pressing step S4 of the cylinder 10 according to one embodiment.

The pressing step S4 includes a plug inserting step of inserting a plug having an outer diameter close to the inner surface of the tube and having an opening 180 of a specific shape into the other end of the tube, And a removing step of pressing and removing.

In the pressing step S4, a part of the cylindrical surface of the tube is removed to form a front surface of the opening part 180, and a part of the cylindrical surface of the tube subjected to the front- And a side pressing step of manufacturing the side pressing step.

9 (a) shows the plug used in the front pressing step, and FIG. 9 (b) shows the shape of the cylinder 10 manufactured by the front pressing step Partial perspective view. As shown, the frontal pressing step is for fabricating the front face of the opening 180.

10 shows a side press step of the cylinder 10 according to an embodiment of the present invention. (a) shows the plug used in the side press step, and (b) is a partial perspective view showing the shape of the cylinder 10 manufactured by the side press step. As shown, the side pressing step is a step for completing the opening portion 180 and the fastening hole 182 by making the opening portion 180 side.

According to the embodiment of the present invention, when the cylinder 10 is manufactured in the order of the cutting step S1, the chamfering step, the bending step S2, the forming step S3 and the pressing step S4, It is possible to manufacture the cylinder 10 which is precise and has a thickness preserved.

3. Pretensioner

The pretensioner 1 according to the embodiment of the present invention may include a belt spool on which the seat belt 3 is wound as shown in Fig. 2 and includes a gear portion 30 connected to the shaft of the belt spool, . A housing including a belt spool and a gear portion 30 may be provided and a sensing unit for sensing a collision of the vehicle may be provided on the other side of the gear portion 30. [ A cylinder 10 may be provided to surround the outer side of the housing, and a plurality of balls 20 may be included in the cylinder 10. The opening portion 180 of the cylinder 10 may be configured so as to be tangent to the gear portion 30 so that the ball 20 and the gear portion 30 are engaged with each other.

When the explosive member 40 provided in the explosive portion 12 is detonated by triggering a vehicle collision, the high-pressure gas generated in the explosive portion 12 pushes the ball 20, 20 rotate the gear portion 30 clockwise in Fig. The rotated gear portion 30 is connected to the shaft of the belt spool so that the seat belt 3 is inserted.

As described above, those skilled in the art will appreciate that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

1: pretensioner 3: seat belt
10: cylinder 11: guide
12: explosion part 13: first bending part
14: first straight section 15: second bending section
16: second straight line section 17: third bending section
18: Ending section 20: Ball
30: gear portion 40: explosive member
120: direction part 180: open part
182: fastening hole

Claims (11)

A method of manufacturing a cylinder used in a pretensioner for a seat belt of a vehicle using a hollow tube made of a steel material having a cylinder of a specific diameter,
a) a cutting step in which the user cuts the tube to a specific length;
b) bending the bend of the tube;
c) a molding step of forming one end of the bended tube by a specific diameter into a specific diameter and press-molding the end portion thinned by axial expansion in the axial direction;
and d) a pressing step of removing a part of the cylindrical surface of the other end of the tube,
The change of the thickness of the tube is within 5% before and after the molding step,
Wherein the forming step fixes the tube to the mold and joins the outer diameter of the tube to the inner diameter of the expanding tube.
The method according to claim 1,
Wherein the pressing step comprises:
A plug inserting step of inserting a plug having an outer diameter in close contact with an inner surface of the tube and having an opening of a specific shape at the other end of the tube; And
A removing step of pressing and removing a portion of the tube corresponding to the opening;
Wherein the pre-tensioner is made of a synthetic resin.
The method according to claim 1,
An opening is provided at the other end of the tube,
Wherein the pressing step comprises:
A front pressing step of removing a part of the cylindrical surface of the tube to produce a front surface of the opening part; And
A side press step of removing a part of the cylindrical surface of the tube through the front press step S4 to manufacture a side surface of the open part;
Wherein the pre-tensioner is formed of a synthetic resin.
The method according to claim 1,
Between the cutting step and the bending step,
A chamfering step of taking the end of the cut tube under a specific condition;
Wherein the pre-tensioner is formed of a synthetic resin.
The method according to claim 1,
The forming step comprises:
A first expanding step of expanding one end of the tube to have two ends;
A second enrichment step of achieving a specific diameter of the tube that the user targeted, further extending the one end of the tube once expanded; And
A press-fitting step of press-fitting in the axial direction to thicken one end of the tube twice expanded;
Wherein the pre-tensioner is made of a synthetic resin.
The method according to claim 1,
The forming step comprises:
A press-fitting step of press-fitting in an axial direction to thicken one end of the tube;
A first expanding step of expanding one end of the tube after the press-fitting step to have two ends; And
A second enrichment step of achieving a specific diameter of the tube that the user targeted, further extending the one end of the tube once expanded;
Wherein the pre-tensioner is made of a synthetic resin.
The method according to claim 1,
Wherein the bending step is performed a plurality of times and bending at 90 degrees in the axial direction of the tube and a mandrel is inserted into the inner diameter of the tube to be bent.
A cylinder of a pretensioner for a seat belt of a vehicle, which is manufactured through a hollow tube made of a steel material having a cylinder of a specific diameter,
An explosion part of which one end of the tube is made expanded and in which an explosive member is mounted;
A guide in which the balls are moved by the high-pressure gas generated in the explosion part; And
An opening part through which the balls reach the guide by the high pressure gas when the high pressure gas is generated and the gear part of the pretensioner engages with the ball;
Lt; / RTI >
A cylinder of a pretensioner for a seat belt of a vehicle, which is manufactured by the manufacturing method according to claim 1.
9. The method of claim 8,
Wherein the difference between the thickness of the explosion portion and the thickness of the guide is about 5% of the thickness of the guide.
9. The method of claim 8,
Wherein a circularity of the inner diameter of the guide is the same as a straight section of a bending section which is a bent section.
A pretensioner for a seat belt of a vehicle,
A belt spool around which the seat belt is wound;
A gear portion connected to one side of the shaft of the belt spool and rotated integrally with the belt spool; And
A cylinder which is opened at one end and is tangent to the gear portion, an explosion member at the other end, a ball which is movable along the guide, and which is configured to engage the ball and the gear portion at an open end;
Lt; / RTI >
Wherein when the explosive member is exploded to generate high-pressure gas in the cylinder, the ball reaches the gear portion by the high-pressure gas, and the ball and the gear portion are intermeshed to rotate the belt spool about the shaft, The seat belt is wound,
The pretensioner for a seat belt of a vehicle according to claim 1, wherein the cylinder is manufactured by the manufacturing method according to claim 1.

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