Method and apparatus for perforating a pipe wall

Abstract

A method and apparatus for perforating a tube wall. In the method, the tube is moved in the longitudinal direction of the tube to a punching position which includes a cutting punch (2) and a three-part die (3, 5, 8) within the tube. By moving a wedge (8) in a first transfer direction towards the free end of the die, the die (3, 5, 8) is expanded in the direction of movement of the cutting punch by means of the wedge surfaces (8a, 8b) of the wedge (8) between the die parts (3, 5). The cutting punch (2) is used for punching a hole in the tube wall, the hole being supported by the expanded die (3, 5, 8) during punching, and thus the sheet-like material punched out from the tube falls into the hole (16) of the upper die part (3). The die is contracted by moving the wedge (8) a first transfer distance in a second transfer direction. The die parts (3, 5) then pivot towards each other in an articulated manner and do not contact the inner surface of the tube. The perforated tube is moved in its longitudinal direction away from the punching position and the tube is moved to a position for finishing the edge of the hole. The lower die part (5) and the wedge (8) are further moved together a second transfer distance in the second transfer direction, so that the base of the hole (16) is opened and the sheet-like material punched out from the tube falls through the hole (16).

Description

Background Art

[0001] A method for perforating a tube wall using a puncher, the puncher including a body, a cutting punch, and a three-part die having an upper die part, a lower die part, and a wedge between the upper die part and the lower die part. The method includes the following steps:

[0002] Moving the tube in the longitudinal direction of the tube to a punching position where the die is inside the tube,

[0003] Expanding the die in the movement direction of the cutting punch by moving the wedge towards the end of the die in a first transfer direction,

[0004] Perforating the wall of the tube using the cutting punch while supporting the wall with the expanded die during punching, so that the sheet removed from the tube falls into a hole in the upper die part,

[0005] Contracting the die by moving the wedge in a second transfer direction opposite to the first transfer direction,

[0006] Moving the perforated tube away from the punching position in the longitudinal direction of the perforated tube, and

[0007] Moving the tube to a position for finishing the edge of the hole.

[0008] An apparatus for perforating a tube wall, the apparatus including a body, a cutting punch, and an elongate die. The cutting punch is arranged to reciprocate relative to the body and has the shape and dimensions of a desired hole. The elongate die is supported on the body by means of a support sleeve and the elongate die has a free end. The die includes an upper die part, a lower die part, and a wedge between the upper die part and the lower die part. The upper die part has a hole corresponding to the shape and dimensions of the cutting punch. The wedge can be reciprocated by a first power unit to expand and contract the die.

[0009] A method and apparatus for perforating a tube having a rectangular cross-section by punching are known from patent publication US6128991. By moving the die parts of a two-part die, the tube is centered relative to the cutting punch part by expanding the die against the side wall of the tube in the transverse direction.

[0010] A method and apparatus for punching a perforation in a tube having a rectangular cross-section are also known from patent publication JPH11244957A. Among them, by moving an intermediate die part, a three-part die is expanded against the inner surface of the tube in the moving direction of the cutting punch, and a wedge surface on the lower surface of the intermediate die part cooperates with a wedge surface on the upper surface of the lowest die part. The highest die part is attached to the body, and the lowest die part is supported by a pivot on the base of the highest die part. Below the die, the lower surface of the tube is supported on the body to receive the punching force of the cutting punch. The reciprocating movement of the intermediate die part is used to expand the die, and the travel distance is limited to the operating area of the wedge surface. When the tube is pulled out, the sheet-like material punched off from the tube first abuts against the inner surface of the tube and may scratch the inner surface of the tube. In addition, when the tube is pushed into the punching position and pulled out of the punching position, the die part drags along the inner surface of the tube. This may also scratch the inner surface of the tube.

[0011] When a cylinder or ferrule branched from the tube wall is formed in the tube by stretching the wall material of the tube, a suitable guide hole must first be made in the wall, and the desired cylinder or ferrule can be stretched from the edge of the guide hole. The hole must have the following quality: the edge of the hole withstands the stretching (so-called collaring) to form the desired ferrule.

[0012] The fastest known way to make a hole in a relatively thin wall is by punching. However, punching cannot produce a high enough quality for stretching a branched cylinder or ferrule. When stretched, the material tears at the edge of the hole made by punching.

[0013] Another known way to make a high-quality hole for collaring purposes is to machine the hole by milling. From a production point of view, milling is a slow way to make a hole of the desired shape because it requires cutting a large amount of material. Summary of the Invention

[0014] In the present invention, these two known perforation methods are combined in the following way: first, a guide hole is made by punching and then the guide hole is finish-machined by milling. For this purpose, a fast and efficient method and apparatus for making a hole by piercing or punching have been proposed in the present invention.

[0015] The object of the present invention is to provide a method and apparatus for effectively producing a guide hole that meets the requirements for collaring in the initial process stage of the collaring process. The method and apparatus according to the present invention must be particularly suitable for perforating a circular tube without deforming the tube, scratching the tube, or otherwise damaging the tube.

[0016] This object is achieved by the method according to claim 1. This object is also achieved by means of the device according to claim 4. The dependent claims disclose preferred embodiments of the invention. Description of the Drawings

[0017] Embodiments of the present invention will be described below with reference to the accompanying drawings, in which:

[0018] Figure 1 A top view of a perforating device according to the present invention is shown,

[0019] Figure 2 is shown Figure 1 a sectional view along line II-II of

[0020] Figure 3 a side view of a device according to Figure 1 and Figure 2 is shown,

[0021] Figure 4 a diagonal top view of the same device is shown,

[0022] Figure 5 a diagonal top view of a wedge is shown,

[0023] Figure 6A the upper die part is shown diagonally from above, Figure 6B the upper die part is shown diagonally from below, and

[0024] Figure 7A the lower die part is shown diagonally from below, Figure 7B the lower die part is shown diagonally from above. Detailed Description of the Invention

[0025] The device includes a body 1 and a cutting punch 2 which is arranged to reciprocate relative to the body 1 and the cutting punch blade of the cutting punch 2 has the shape and dimensions of a desired hole. Elongated dies 3, 5, 8 are supported on a support sleeve 14 attached to the body 1 and the dies 3, 5, 8 project from the support sleeve 14. The dies 3, 5, 8 have free ends around which a tube to be perforated can be pushed in the direction of the free ends. The dies 3, 5, 8 include an upper die part 3 and a lower die part 5 and a wedge 8 between the upper die part 3 and the lower die part 5, and the upper die part 3 has a hole 16 corresponding to the shape and dimensions of the cutting punch, and the wedge 8 can be reciprocated in the longitudinal direction of the die by a first power unit 9 to expand and contract the die.

[0026] The tube to be perforated is moved in its longitudinal direction to the punching position so that the three-part die 3, 5, 8 is pushed into the interior of the tube. The upper die part 3 (i.e., the die part on the cutting punch 2 side) is attached to the support sleeve 14 by means of a swivel joint 4 which allows the upper die part 3 to perform a rotational movement in the movement direction of the cutting punch 2 within the range permitted by the support sleeve 14 and the wedge 8. Due to this articulated support, the cutting punch side of the upper die part 3 is positioned inside the inner surface of the moving tube without contacting the inner surface of the tube during the tube pushing phase.

[0027] As visible in Figure 6A and Figure 6B the upper die part 3 includes an arm 3a having a hole 4a. The swivel joint 4 includes a bolt with a pin penetrating the hole 4a. This means that the die part 3 can be easily replaced by another die part 3 having a similar arm 3a but with an actual die part 3 whose dimensions are adapted to the desired tube diameter and hole size.

[0028] The lower die part 5 is attached to the carriage 10 moved by the second power unit 12 by means of a swivel joint 6 which allows the lower die part 5 to perform a rotational movement in the movement direction of the cutting punch 2 within the range permitted by the support sleeve 14 and the wedge 8.

[0029] As can be seen from Figure 7A and Figure 7B the lower die part 5 includes an arm 5a having a hole 6a. The swivel joint 6 includes a bolt with a pin penetrating the hole 6a. Thus the die 6 can be easily replaced by another die which has a similar arm 6a but with an actual die part 5 whose dimensions are adapted to the desired tube diameter and hole size.

[0030] As Figure 5 shown, the wedge 8 has wedge-shaped surfaces 8a, 8b on both sides which cause the die parts 3, 5 to rotate away from each other in an articulated manner to expand the die when the first power unit 9 moves the wedge 8 towards the free ends of the dies 3, 5, 8. The wedge 8 includes an arm 18 having a hole 7b penetrated by a bolt with a pin 7a, and the moving part 7 of the power unit 9 (such as the piston rod 7 of a piston-cylinder device) is attached to the arm 8a of the wedge 8 by means of this arm 18. In this case, the wedge 8 can also be easily replaced, and this replacement is related to the replacement of the dies 3, 5. When the dimensions and shapes of the arms 3a, 5a, 18 of the die parts and the wedge remain unchanged, the support sleeve 14 does not need to be replaced.

[0031] The first power unit 9 is adapted to move the wedge 8 a first transfer distance in the contracting direction. The second power unit 12 is adapted to move the lower die part 5 and the wedge 8 together a second transfer distance, which is an extension of the first transfer distance. Due to this second transfer distance, the base of the hole 16 in the upper die part 3 opens and the punched-out sheet drops off. Before that, the die has contracted and the tube has been removed from around the die, and thus the dropped sheet does not scrape the inner surface of the tube.

[0032] Arrow 17 marks the power unit, such as an elastic member, which rotates the lower die part 5 upward relative to the axis of rotation formed by the swivel joint 6 as the wedge 8 moves backward (i.e., in the contracting direction). Thus, when the perforated tube is pulled away from the punching position, the lower die part does not drag along the inner surface of the tube. When the die part contracts, the upper die part 3 rotates downward due to gravity.

[0033] There is a threshold 15 on the lower surface of the lower die part 5, which is adapted to rest against the support sleeve 14 at the start of the second transfer distance and turn the lower die part 5 upward, or support the lower die part 5 in the position where it has been turned upward and the elastic member 17 has turned the die part 5.

[0034] The first power unit 9 is preferably a piston-cylinder device, the cylinder of which is attached to the bracket 10 and the piston rod 7 is attached to the wedge 8 with a pin bolt 7a. The piston rod 7 and the pin bolt 7a can move through the opening of the bracket 10. The second power unit 12 is preferably also a piston-cylinder device, the cylinder of which is attached to the body 1 and the piston rod is attached to the bracket 10.

[0035] In the illustrated embodiment, there is a wedge-shaped surface on the lower surface of the upper die part 3 that slopes downward toward the free end of the die, so that the upper die part 3 thickens toward its end. The upper surface of the lower die part 5 slopes upward, so that the lower die part 5 thickens toward its free end. The wedge angles of the wedge-shaped surfaces of the die parts 3, 5 are the same as the wedge angle of the wedge-shaped surface of the wedge 8. This provides the largest possible wear surface and a solid die.

[0036] The moving direction of the bracket 10 and accordingly the moving directions of the wedge 8 and the lower die part 5 are the same as the moving direction and the axial direction of the tube. When the power unit 9 moves the wedge 8 toward the free end of the die, the wedge 8 is on the center line of the die and causes a symmetric expansion of the dies 3, 5, 8 in the moving direction of the cutting punch.

[0037] The cutting punch 2 is used to punch a hole in the tube wall, and the tube wall is supported by the expanding dies 3, 5, 8 during the punching. The flakes punched off from the tube fall into the hole 16 of the upper die part 3. When the perforated tube moves to the next working stage, the flakes must not fall into the tube and drag along the inner surface of the tube or follow the tube. The perforated tube moves away from the punching position in its longitudinal direction, and the tube is moved to the finishing position at the hole edge, in which the edge of the hole cut by the cutting punch is finished (by cutting) with a rotary blade, and the movement of the rotary blade follows the shape of the punching. When the hole is made in the wall of the round tube for manufacturing the branch collar, the shape of the hole is more or less oval. In this case, the curvature of the cross-section of the upper and lower surfaces of the dies 3, 5, 8 also corresponds to the curvature of the inner surface of the round tube. The width of the die is slightly smaller than the cross-section of the tube.

[0038] Before punching the hole, by means of the wedge-shaped surfaces 8a, 8b of the wedge 8, the dies 3, 5, 8 are expanded in the movement direction of the cutting punch 2 by moving the wedge 8 relative to the die parts 3, 5 in the first transfer direction (towards the free end of the die). During the transfer movement of the wedge 8 and the expansion of the dies 3, 5, 8, the dies 3, 5, 8 are supported in the support sleeve 14, and the dies 3, 5, 8 extend from the support sleeve 14 to the outside of the support sleeve 14. At the end of the transfer movement of the wedge, the wedge-shaped surfaces 8a, 8b expand the die by rotating the upper part and the lower part of the die to contact the inner surface of the tube. During punching, the punching force is transferred to the support structure (not shown) on the other side of the tube by means of the dies 3, 5, 8 without flattening the tube.

[0039] After punching, the wedge 8 moves a first transfer distance in the second transfer direction, which causes the die to contract by allowing the die parts 3, 5 to rotate towards each other in a hinged manner. When the upper die part rotates downward and the elastic member 17 causes the lower die part 5 to rotate upward, the die is no longer pressed against the tube wall and the die parts 3, 5 are disengaged from the contact with the inner wall of the tube. Then, when the tube is pulled away from the punching position, the die is no longer in contact with the inner surface of the tube. The limiting part 15 on the lower surface of the lower die part 5 is adapted to rest against the support sleeve 14, and when the lower die part 5 and the wedge 8 move a second transfer distance, the lower die part 5 is kept turned upward. Then, the base of the hole 16 opens and the fallen flakes fall out of the tube.

[0040] Thereafter, the lower part 5 of the die and the wedge 8 are returned by the power unit 12 and the carriage 10 towards the free end of the die by a second transfer distance, whereupon the device is ready to receive the next tube to be pierced. The hole 16 has the same dimensions as the cutting punch, and the hole 16 to be made in the tube is conically enlarged downwards (i.e., in the direction of the working movement of the cutting punch 2) by the wedge 8 and the lower die part 5 over a certain distance.

[0041] Preferably, the first transfer distance is less than the second transfer distance. The carriage 10 is supported on a body (not shown) outside the device by means of linear bearings 11, and the body 1 of the device is also attached to the body outside the device by means of a body flange 1a.

Claims

1. A method for perforating the wall of a tube using a punch, the punch comprising a body (1), a cutting punch (2) and a three-part die (3, 5, 8), the three-part die (3, 5, 8) having an upper die part (3), a lower die part (5) and a wedge (8) between the upper die part (3) and the lower die part (5), the method comprising the steps of: Moving the tube in the longitudinal direction of the tube to a punching position at which the die (3, 5, 8) is inside the tube, Expanding the die (3, 5, 8) in the direction of movement of the cutting punch by moving the wedge (8) towards the end of the die in a first transfer direction, Perforating the wall of the tube with the cutting punch (2) while supporting the wall with the expanded die (3, 5, 8) during punching, whereby the flakes punched out from the tube fall into a hole (16) in the upper die part (3), Contracting the die (3, 5, 8) by moving the wedge (8) in a second transfer direction opposite to the first transfer direction, Moving the perforated tube away from the punching position in the longitudinal direction of the perforated tube, and Moving the tube to a position for finishing the edge of the hole, Characterized in that the die (3, 5, 8) is supported by a support sleeve (14) attached to the body (1), the die (3, 5, 8) remaining non-contact with the inner surface of the tube surrounding the die (3, 5, 8) during the transfer movement of the tube and being brought into contact during expansion such that as the wedge moves in the first transfer direction, the upper wedge part rotates upwards and the lower wedge part rotates downwards, after punching, the wedge (8) moves a first transfer distance in the second transfer direction, the first transfer distance causing the die parts (3, 5) to rotate towards each other in a hinged manner to contract the die, the perforated tube moves away from the punching position, and the lower part (5) of the die and the wedge (8) then move together a second transfer distance in the second transfer direction, thus opening the base of the hole (16) in the upper die part, whereby the flakes punched out from the tube pass through the hole (16) and fall out.

2. The method according to claim 1, characterized in that, At the start of the second transfer distance of the lower part (5) of the die and the wedge (8) in the second transfer direction, the lower part (5) of the die is rotated upwards or supported in an upwards-rotated position by supporting the lower part (5) of the die on the support sleeve (14) by means of a limit part (15) on the lower surface of the lower part (5) of the die.

3. The method according to claim 1 or 2, characterized in that, An oval hole is made in the wall of a tube having a circular cross-section by means of the method.

4. A device for perforating a pipe wall, the device comprising: A body (1), a cutting punch (2), and elongated dies (3, 5, 8). The cutting punch is arranged to reciprocate relative to the body and has the shape and dimensions of a desired hole. The dies (3, 5, 8) are supported on the body (1) by means of a support sleeve (14), and the dies (3, 5, 8) have free ends. The dies (3, 5, 8) include an upper die part (3), a lower die part (5), and a wedge (8) between the upper die part (3) and the lower die part (5). The upper die part has a hole (16) corresponding to the shape and dimensions of the cutting punch. The wedge (8) can reciprocate by means of a first power unit (9) to expand and contract the die (3, 5, 8). It is characterized in that the upper die part (3) is attached to the support sleeve (14) by means of a rotary joint (4), and the rotary joint (4) allows the upper die part (3) to perform a rotational movement in the direction of movement of the cutting punch (2) within the range allowed by the support sleeve (14) and the wedge (8). The lower die part (5) is attached to a carriage (10) moved by a second power unit (12) by means of a rotary joint (6), and the rotary joint (6) allows the lower die part (5) to perform a rotational movement in the direction of movement of the cutting punch (2) within the range allowed by the support sleeve (14) and the wedge (8). The wedge (8) has wedge-shaped surfaces (8a, 8b) on both sides. When the first power unit (9) moves the wedge (8) towards the free end of the die (3, 5, 8), the wedge-shaped surfaces (8a, 8b) cause both die parts (3, 5) to pivot away from each other in a hinged manner to expand the die. The first power unit (9) is adapted to move the wedge (8) a first transfer distance in the contraction direction, and the second power unit (12) is adapted to move the lower die part (5) and the wedge (8) together a second transfer distance. The second transfer distance is an extension of the first transfer distance, and due to the second transfer distance, the base of the hole (16) in the upper die part (3) opens.

5. The device according to claim 4, characterized in that, A limiting part (15) is provided on the lower surface of the lower die part (5). The limiting part (15) is adapted to rest against the support sleeve (14) and, at the start of the second transfer distance, cause the lower die part (5) to rotate upward or support the lower die part (5) in an upwardly rotated position.

6. The device according to claim 4 or 5, characterized in that, The first power unit (9) is a piston-cylinder device. The cylinder of the piston-cylinder device is attached to the carriage (10), and the piston rod is attached to the wedge (8).

7. The device according to any one of claims 4 to 6, characterized in that, The second power unit (12) is a piston-cylinder device. The cylinder of the piston-cylinder device is attached to the body (1), and the piston rod is attached to the carriage (10).

8. The device according to any one of claims 4 to 7, characterized in that, On the lower surface of the upper die part (3) there is a wedge surface which slopes downwards towards the free end of the die (3, 5, 8), so that the upper die part (3) becomes thicker towards the end of the upper die part (3), and the upper surface of the lower die part (5) slopes upwards, so that the lower die part (5) becomes thicker towards the free end of the lower die part (5).

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