Process for extruding tube having different sections and die for tube extrusion molding

• US 20020108425A1
• Filed: 01/31/2002
• Published: 08/15/2002
• Est. Priority Date: 01/31/2001
• Status: Active Grant

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Hoshi, Konomu, Yanagibashi, Yoshitaka
• Granted Patent: US 6,681,610 B2
• Time in Patent Office: Days
• US Class Current: 72/260
• CPC Class Codes: B21C 23/085 Making tubes B21C23/10 take precedence
• CPC Class Codes: B21C 25/08 Dies or mandrels with section variable during extruding, e.g. for making tapered work; Controlling variation
• CPC Class Codes: B62K 11/04 characterised by the engine being between front and rear wheels
• CPC Class Codes: B62K 19/06 tubular

Abstract

The present invention relates to an easy and cost effective process for extruding a tube having different intermediate sections in its longitudinal direction, and a die for forming a tube through this extrusion molding process. Tubes so formed may be used for a vehicle for example, particularly for the body frame of a motorcycle. The die for this extrusion molding process includes a fixed die and a movable variable die. The tube is formed by material extruded from an outflow passage which is formed by the superposition in the direction of extrusion of a fixed die hole and a variable die hole. The outflow passage has an opening for a tube wall for forming the wall of the tube, and openings for two intermediate walls for forming connecting walls in the inside space of the tube. The tube formed by this process is composed of a part having the connecting wall and a part having no connecting wall. This is accomplished by opening or blocking the opening for the intermediate wall by moving cores according to the amount of the movement of the variable die. The resulting tube has a rigidity that varies along the longitudinal direction of the tube.

Claims

1. A process for extruding a tube having different sections where the tube is formed by using a die for tube extrusion molding having a first die and a second die which are superposed in a direction of extrusion, the first die and the second die being relatively movable in a set direction along the superposed surface, in order to permit the extrusion of a material via an outflow passage formed by the superposition in the direction of extrusion of a first die hole formed in the first die and a second die hole formed in the second die, and thereby causing a sectional form of the tube to be varied in the direction of extrusion by relatively moving the first die and the second die in the set direction, comprising the steps of:

providing the outflow passage with an opening for a tube wall and at least one opening for an intermediate wall which continues to the opening for the tube wall inside the opening for the tube wall;

extending the opening for the tube wall for a predetermined width in a first direction which is a direction when the set direction is projected on a plane perpendicular to the direction of extrusion, and extending the opening for the tube wall in a second direction crossing the first direction on the perpendicular plane;

relatively moving the first die and the second die in the set direction;

extruding the material from opening for the tube wall and the opening for the intermediate wall;

forming the tube wall having a width in the first direction which varies in a longitudinal direction by varying the opening for the tube wall; and

simultaneously forming the intermediate wall being formed in an inside space of the tube, and having a fixed thickness and a predetermined width in the first direction, extending in the longitudinal direction, and continuing to the tube wall in the inside space of the tube.

2. The process for extruding a tube having different sections according to claim 1, wherein:

the intermediate wall is at least one connecting wall which connects two tube wall parts opposite in the second direction of the tube wall, and which partitions the inside space into a plurality of independent partial spaces on the section of the tube; and

the number of the connecting walls in the longitudinal direction of the tube is changed by opening or blocking at least one of the openings for the intermediate walls according to an amount of the relative movement in the set direction of the first die and the second die.

3. The process for extruding a tube having different sections according to claim 2, wherein the number of connecting walls is two or more and these connecting walls may extend in the longitudinal direction by different lengths.

4. The process for extruding a tube having different sections according to claim 2, wherein a width of the connecting walls increases or decreases in the longitudinal direction from the extrusion start end.

5. A process for extruding a tube having different sections, comprising the steps

superimposing a first die and a second die in a direction of extrusion;

providing an outflow passage having an opening for a tube wall and at least one opening for an intermediate wall which continues to the opening for the tube wall inside the opening for the tube wall;

extending the opening for the tube wall for a predetermined width in a first direction which is a direction when the set direction is projected on a plane perpendicular to the direction of extrusion, and extending the opening for the tube wall in a second direction crossing the first direction on the perpendicular plane;

relatively moving the first die and the second die in the set direction;

extruding the material from opening for the tube wall and the opening for the intermediate wall;

forming the tube wall having a width in the first direction which varies in a longitudinal direction by varying the opening for the tube wall; and

simultaneously forming the intermediate wall in an inside space of the tube, the intermediate wall having a fixed thickness and a predetermined width in the first direction, extending in the longitudinal direction, and continuing to the tube wall in the inside space of the tube.

6. The process for extruding a tube having different sections according to claim 5, further comprising the steps of:

causing the intermediate wall to partition the inside space into a plurality of independent partial spaces on the section of the tube, the intermediate wall being at least one connecting wall which connects two tube wall parts opposite in the second direction of the tube wall.

7. The process for extruding a tube having different sections according to claim 6, further comprising the steps of:

changing the number of the connecting walls in the longitudinal direction of the tube by opening or blocking at least one of the openings for the intermediate walls according to an amount of the relative movement in the set direction of the first die and the second die.

8. The process for extruding a tube having different sections according to claim 6, wherein the number of connecting walls is two or more and these connecting walls may extend in the longitudinal direction by different lengths.

9. The process for extruding a tube having different sections according to claim 6, wherein a width of the connecting walls increases or decreases in the longitudinal direction from the extrusion start end.

10. A die for tube extrusion molding comprising:

a first die and a second die which are superposed in a direction of extrusion and which are relatively movable in a set direction along the superposed surface,

said first die having a first die hole formed by a void between a first peripheral wall of a first hole formed in the first die and a first core arranged in the first hole and integrated with the first die,

said second die has a second die hole formed by a void between a second peripheral wall of a second hole formed in the second die and a second core arranged in the second hole and integrated with the second die;

an outflow passage formed by the superposition in the direction of extrusion of the first die hole and the second die hole for extruding a material to form a tube;

said first core being composed of a plurality of child cores arranged in parallel, having predetermined width in a first direction which is a direction when the set direction is projected on a plane perpendicular to the direction of extrusion, and forming a void between the plurality of child cores extended in a second direction crossing the first direction on the perpendicular plane;

said outflow passage having an opening for a tube wall formed by a void between the first peripheral wall or the second peripheral wall and the first core or the second core, and also having an opening for a first intermediate wall defined by the void between the first cores and continuing to the opening for the tube wall;

the first die and the second die being superposed so that the maximum interval in the first direction of the opening for the tube wall can be varied according to the amount of the relative movement in the set direction of the first die and the second die;

the second core keeping at least one of the openings for the first intermediate wall in an open state by the predetermined width and in a blocked state.

11. The die for tube extrusion molding according to claim 10, wherein:

the void between the first cores is continuously extended in a second direction;

the second core is composed of a plurality of child cores arranged in parallel respectively having a predetermined width in the first direction and forming a void between at least one of the second cores continuously extended in the second direction;

the outflow passage has an opening for a second intermediate wall defined by a void between the second cores and continuing to the opening for the tube wall; and

the first die and the second die are superposed so that the first core keeps at least one of the openings for the second intermediate wall in an open state by the predetermined width and in a blocked state according to an amount of the relative movement in the set direction of the first die and the second die.

12. The die for tube extrusion molding according to claim 10, wherein:

the intermediate wall is at least one connecting wall which connects two tube wall parts opposite in the second direction of the tube wall, and which partitions the inside space into a plurality of independent partial spaces on the section of the tube; and

the number of the connecting walls in the longitudinal direction of the tube is changed by opening or blocking at least one of the openings for the intermediate walls according to an amount of the relative movement in the set direction of the first die and the second die.

13. The die for tube extrusion molding according to claim 12, wherein:

the number of connecting walls is two or more and said connecting walls extend in the longitudinal direction by different lengths.

14. The die for tube extrusion molding according to claim 12, wherein:

a width of the connecting walls increases or decreases in the longitudinal direction from the extrusion start end.