JP2005511307A - Method and apparatus for tube notching and tube obtained by carrying out the method - Google Patents

Abstract

  A tube notching method comprising the reciprocating movement of at least one pressing roller during which the roller locally pushes the wall of the tube (1) to cause plastic deformation and the movement of the pressing roller is A method characterized in that it is formed by a combination of at least two displacements: That is, a first displacement reciprocating substantially linearly, during which the roller is pressed against the wall of the tube (1) to roll, and a second displacement called forward movement, this first displacement The resultant force of the two displacements is substantially perpendicular to the direction of the first displacement, and the plastic deformation of the tube (1) is obtained during at least two passes by the pressing roller.

Description

The present invention relates to a method and apparatus for tube notching.
As used herein, “tube” refers to a hollow, particularly cylindrical, open or closed member formed of a metallic material or any other equivalent material.

In many industrial fields it is necessary to form notches in hollow tubes, such notches being formed for example for ratcheted support bars for handbrakes, racks or skeletons of automobile headrests. .
Especially in this last application, in order to obtain a clear adjustment of the height of the headrest and to avoid the headrest being easily displaced and out of position, for example when a weak pressure is applied by a child, The notch that is to be made must have a sharp and clear edge.

The framework of a U-shaped headrest with a notch is described in the following document, for example.
French patent application Nos. 2755915, 2751926, 2734612, 2734216, 2272267, 2704188, 2667771.
European patent applications 1108607, 1046541, 953477, 875417, 743222, 687590, 412307.
US Patents 5478136, 5398996, 5257533, 5165754, 4390209.

Also in the prior art, various methods are already known which can give clear notching to the tube with or without material removal.
Pipe notching, which is accompanied by material removal by machining, has a number of drawbacks and has not been studied anymore because it makes the pipe very brittle.
On the other hand, a number of methods for notching pipes without material removal have been proposed in the prior art.

The document EP-A-0974409 provides a punch adapted to the notching profile to be formed instead of a pierced former for a known hammering machine having a planetary gear and a ball cap. It describes a notching method using a hammer. This punch is driven by a complex motion that is broken down into translational and orbital motion. The tube that receives the notching is disposed in the groove of the fixed half mold, and the movable half mold or the fixing jig (serre-flan) is provided with a groove facing the groove of the fixed half mold.
The above method described in document EP-A-0974409 has a number of drawbacks. In particular, the productivity obtained is very low and it is difficult to meet the demands of the automobile assembly department. Furthermore, as described in this prior art document, the punch movement is complex and difficult to control, so that the notch punch rotation is blocked by the anti-reverse device on the pipe. It has been found that the quality of the resulting notch tends to vary.

Document FR-A-2805481 describes a method of notching a tube by extrusion (stamping) using a press. This method uses a mold comprising a lower mold part, a right upper mold part, and a left upper mold part. The lower mold part is provided with a recess for receiving a notching tube. Next, the left and right upper mold parts are pressed against the notching pipe, and the obtained mold has a plurality of through holes, and a plurality of punches passing through the through holes stamp the pipe.
The above-described method described in document FR-A-2805481 has a number of drawbacks. In particular, to minimize weakening due to shear, it is necessary to adjust the notched site and the size of the notch. Otherwise, a flash is formed in the notch. The notching of the pipe due to deformation under the press as described in the document FR-A-2805548 leads to bending, and therefore it is necessary to repeat machining to obtain a sharp angle. The productivity obtained by this stamping is not high.

  In order to control the thickness and cross section of the tube during notching by stamping, document EP-A-1112791 proposes the use of a mandrel and multiple pressing operations. Such a method does not allow great productivity and, of course, cannot be performed with closed tubes.

  Document WO-A-01 / 15827 describes a notching device having a slide-type forming tool.

  Other examples of the notching method of the pipe are described in the documents of DE-U297717174, DE-U-29714315, and EP-A-0867334.

It is an object of the present invention to provide a method and apparatus for pipe notching that does not have the disadvantages of the methods and apparatuses known to date.
The present invention, in particular, ensures high productivity and better regularity with respect to the shape of the notch, there is no casting, no repetitive machining is required, with material removal and significant reduction in tube durability. It is an object of the present invention to provide a method capable of forming a notch without forming a notch.

To that end, a first aspect of the present invention relates to a method of notching a tube, the method comprising the step of reciprocating at least one pressing roller, during which the roller presses the wall of the tube locally. Plastically deforming, the movement of the pressing roller is formed by a combination of at least two displacements:
A first displacement reciprocating substantially linearly, during which the roller is pressed against the wall of the tube and rolls;
A second displacement called forward, the resultant of this second displacement is approximately perpendicular to the direction of the first displacement, and the plasticity of the tube during at least two passes by the pressing roller. A deformation is obtained.

  According to one characteristic, the method includes the step of controlling a pressing force of the pressing roller against the tube and a parameter selected from the group comprising the position of the roller upon contact with the tube.

  A second feature of the present invention relates to an apparatus for carrying out the method defined above, the apparatus comprising means for temporarily holding at least one tube in place and said pressing roller in a first position. And mechanically driving means according to the displacement.

According to various embodiments, the apparatus comprises the following features that may be combined with each other:
The apparatus includes means for encouraging the controlled second displacement of the pressing roller, referred to as forward displacement, the means comprising means selected from the group comprising a spring and an actuator such as a jack. Including;
The apparatus has a carriage driven while supporting a roller, the carriage is reciprocated according to the first displacement, and is rotated around an axis substantially perpendicular to the direction of the first displacement. Is freely supported;
The apparatus comprises three pressing rollers having substantially the same diameter and whose rotation axis is substantially along the reciprocating direction of the first displacement;
The apparatus includes means for controlling the displacement of the pressing roller according to at least one parameter selected from the group including the pressing force of the pressing roller against the tube and the position of the roller upon contact with the tube. ;
The control is of an electrohydraulic type.

  According to a third aspect, the invention relates to a headrest tube obtained by carrying out a method as defined above.

Other objects and advantages of the present invention will become apparent from the following description of the embodiments. The description is made with reference to the following accompanying drawings:
FIG. 1 is a plan view of a notching device for carrying out the method of the present invention, according to one embodiment,
FIG. 2 is a side view of the device of FIG.
3 is a side view of the device of FIG. 1 along arrow III.

  The following description is made with respect to the notch of the U-tube that is conventionally employed for the headrest skeleton. As will be appreciated by those skilled in the art, the method and apparatus of the present invention provides notch formation for other types of U-tubes, such as U-tubes employed in racks or ratcheted support bars for handbrakes. Is also possible.

In each figure, the U-shaped tube 1 is held in position within the processing volume of the device 3 by means 2 such as a mold with a recess.
In the illustrated embodiment, the tube 1 is introduced into the volume V by movement along the arrow F, and the two substantially parallel legs 4, 5 of the tube extend along the direction D1.
This direction D1 is assumed to be vertical in the description. However, it should be noted that this arrangement is only arbitrarily adopted for simplicity. In fact, as will be appreciated by those skilled in the art, the function of the device is not determined by the orientation of direction D1.

Retaining the position of the tube in the receiving recess can be obtained using means such as clamping jaws.
In the illustrated embodiment, the tube has a substantially circular cross section. However, the method according to the invention can also be used for tubes having an elliptical or polygonal cross section.
The apparatus 3 is provided with three rollers 6, 7, and 8 that are rotatably supported by an axis along the direction D1 and have a predetermined cross section.

  In one embodiment, these rollers 6, 7 and 8 are supported on a carriage that slides along direction D2, which itself can rotate along direction D1 relative to the frame of device 3. A tube 1 for receiving notching is held on the frame. The means for applying the controlled pressure realizes the application of the rollers 6, 7, 8 against the tube 1 to be notched.

In a first particular embodiment, these means comprise a torsion spring supported on the shaft 10.
In a second particular embodiment, these means comprise a compression spring supported between the pressure cradle 11 and the slide frame 12 supporting the rollers 6, 7, 8 and this spring. Is indicated by reference numeral 13 in FIG. In one variant, this compression spring 13 is combined with a torsion spring supported on the shaft 10 of the carriage 12. In one variant, a single-acting jack is arranged instead of the spring 13.

The first and second embodiments described above provide a substantially linear movement along the direction D2 of the carriage supporting the rollers.
However, the Applicant has found that such a substantially linear movement leads to a large residual stress on the notches, and that due to the large plastic deformation of the material forming the tube 1 some of these notches' shapes. It has been confirmed that there is a possibility of causing defects.

In the third embodiment, the carriage 12 supporting the roller is controlled by means such as a double-action jack during the rotational movement around the rotary shaft 10.
In one variation, the control of the jack rod movement is performed in accordance with the movement of the carriage. In another variant, the movement of the jack rod is controlled in accordance with the stress experienced by the carriage as the roller passes over the tube 1, which is the plastic deformation force experienced by the material of the tube 1 during notching. Is reflected.

  Therefore, for example, the roller can be operated so that the pressure changes with respect to the tube 1 such that the pressure gradually increases, then becomes substantially constant, and then gradually decreases. One skilled in the art will be able to experimentally obtain a pressure curve that gives the best compromise for the requirements between manufacturing time and residual stress for a given tube material.

  The forward and backward movements of the carriage supporting the rollers 6, 7, and 8 are mechanized, and the number of reciprocations per minute is as high as about several tens to several hundreds.

The present applicant has made it possible to form a tube while allowing the method described above to obtain significantly greater productivity than previously known methods, while still ensuring great regularity with respect to the shape of the notch. It was confirmed that the material was not thinned at the bottom of the notch.
The device 3 may comprise one, two or more than two rollers. The roller may have a shape that forms a single notch in the tube, or it may have a shape that forms multiple notches.
As shown in the drawing, the plurality of rollers can be arranged such that the rotation shafts are parallel to each other.

In other embodiments not shown, the rotational axes of the rollers are not aligned, for example, to form a negative notch.
In one embodiment, the position of the rotational axis of the plurality of rollers is determined by the position of the tube receiving the notching or the pressing force of the roller against the tube.
In some cases, a plurality of rollers may be arranged along a plurality of rows substantially parallel to each other to form two or more indentations simultaneously.

  As can be readily appreciated by those skilled in the art, it is possible to place the notches along all orientations by clamping the tube 1 along an angle determined relative to the direction D3 in FIG. That is, the inner surface of the pipe as shown in FIG. 1 of the document FR-A-2805481, the outer surface of the tube as shown in the document FR-A-2777686, or the document FR-A-276850. The vicinity of the rear part of the headrest as shown in the official gazette, or the vicinity of the front part of the headrest as discussed in the document FR-A-2758296.

  The method according to the present invention allows notching in a very short time, about a few seconds, to the headrest skeleton tube.

1 is a plan view of a notching device that implements the method of the present invention, according to one embodiment. Side view along arrow II of the device of FIG. Side view along arrow III of the apparatus of FIG.

Claims (9)

A tube notching method comprising reciprocating movement of at least one pressing roller during which the roller locally presses the wall of the tube to cause plastic deformation, and the movement of the pressing roller is at least: A method characterized by being formed by a combination of two displacements:
A first displacement reciprocating substantially linearly, during which the roller is pressed against the tube wall and rolls;
A second displacement called forward, the resultant force of this second displacement is substantially perpendicular to the direction of the first displacement, and the plastic deformation of the tube is obtained during at least two passes by the pressing roller. It is done.   2. The method according to claim 1, further comprising the step of controlling a pressing force of the pressing roller against the tube and a parameter selected from the group including the position of the roller upon contact with the tube.   3. Method according to claim 1 or 2, characterized in that it comprises means for temporarily holding at least one tube (1) in place and means for mechanically driving the pressing roller according to a first displacement. Device to do.   Means for encouraging the controlled second displacement of the pressing roller, referred to as forward displacement, said means comprising means selected from the group comprising an actuator such as a spring and a jack A device according to claim 3.   A carriage driven while supporting a roller, the carriage is reciprocated according to the first displacement, and is rotatable about an axis (10) substantially perpendicular to the direction of the first displacement; A device according to claim 3 or 4, characterized in that it is supported on a device.   7. The method according to claim 3, further comprising three pressing rollers (6, 7, 8) whose diameters are substantially equal to each other and whose rotation axis is substantially along the reciprocating direction of the first displacement. Or device according to one paragraph.   Means for controlling the displacement of the pressing roller according to at least one parameter selected from the group including the pressing force of the pressing roller against the tube and the position of the roller upon contact with the tube. Device according to any one of claims 3 to 6, characterized in that   8. The device according to claim 7, wherein the control is of the electrohydraulic type.   Tube obtained by carrying out the method according to claim 1 or 2, characterized in that it is a tube for the headrest skeleton.

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