Method and apparatus for making pipe T-junctions

Abstract

The object of the invention is a method and an apparatus for making a pipe T-junction by connecting the shaped end of a branch pipe to the edge of the hole of the main pipe by internal welding. The hole of the main pipe (T) and the corresponding circular arc of the main pipe at the end of the branch pipe (P) are mechanically cut in a dry mechanical process by removing one solid part from the hole and two solid parts from the end of the branch pipe. The shaped end of the branch pipe (P) is placed around the hole of the main pipe and the seam (21) between the pipes is welded by internal welding without using weld filler. The appropriate branch hole is made by punching tangentially from the side of the main pipe, so that the tangent of the pipe parallel to the moving direction of the punch tool is located inside the punch tool (1).

Description

[Technical field]

[0001] The object of the present invention is a method and an apparatus for making a pipe T-branch by connecting a shaped end of a branch pipe to the edge of the hole of a main pipe by internal welding.

[0002] Another object of the invention is a device which can be used for drilling the main pipe required in the method.

[0003] The ends of the branch pipes are cut into arcs that correspond to the main pipe, for example using methods and apparatus known from patent publication US10537948, but the cutting depth of the parts removed from the ends of the branch pipes (P) is adjusted to provide an uncut straight end face at the ends of the branch pipes between the arcs corresponding to the main pipe, as shown in Figure 4. This allows an appropriate amount of material to be left on the outer surface of the main pipe, allowing the parts to be welded from the inside without introducing filler from the outside. [Background technology]

[0004] When branching pipes into a T-shape, there are many ways to make holes for the branch connections. For small pipes, the most common method is drilling. Drilling produces chips, which require the use of cutting fluids to drill holes efficiently. The chips and cutting fluids are both production and environmentally disadvantageous. For welding the joints, the chips must be removed and the parts cleaned, usually with hot water. Furthermore, drilling holes in pipes is a relatively time-consuming production method.

[0005] CA2280650 discloses a method for punching holes in curved pipes of an engine exhaust manifold. The punch tool is guided so that its outside faces the outer surface of the pipe. The punched hole is widened using a mandrel with segmented fingers. Finally, a thread is provided for mounting a metal tube carrying a sensor. The design of the tip of the punch tool and the lack of internal support make it impossible to punch holes suitable for making a T-junction. The shape of the hole obtained is not suitable for connecting the shaped ends of the branch pipe by internal welding.

[0006] JP 2001162335 A discloses a method for drilling holes in tubes in such a way that the punch tool penetrates part of the circumference of the tube tangentially and removes the material pushed from the circumference of the tube by the flat front end of the blade. The chamfered part of the blade expels the removed material from the hole. The shape of the blade upsets the material to be removed and causes deformation of the tube, in particular because the non-expandable inner support does not sufficiently support the edge of the hole at the impact point of the punch tool. The hole thus formed is not suitable for connecting the shaped end of a branch pipe by internal welding. This is especially true in the case of large diameters of the branch pipes, since the described method is not suitable for forming holes with diameters close to the diameter of the tube to be drilled. This unsuitability is due to the shape of the blade being such that it crushes the material and the fact that the non-expandable inner support does not prevent deformation of the tube.

[0007] US3120143 discloses a method for punching holes in pipes in a tangential direction to connect T-junctions. The cutting blade of the punching tool first penetrates the pipe at one edge of the hole formed from the outside to the inside of the pipe, and then penetrates the pipe at the opposite edge of the hole formed from the inside to the outside of the pipe. The punching tool has a tapered sharp blade, which is only suitable for thin-walled pipes or soft pipe materials. Such a blade cannot withstand the penetration of a typical thick-walled steel pipe. In addition, the support force on the inside of the pipe is weak, which causes the pipe to deform, making it unsuitable for manufacturing T-junction joints.

[0008] The simplest way to make a hole suitable for making a T-junction is the typical punching method, where a round punch tool is used to make a hole perpendicular to the longitudinal axis of the pipe. This works when the branch pipe is a certain amount smaller than the main pipe. To make a hole in the pipe that can connect a branch pipe of the same size or approximately the same size as the pipe itself, the typical punch and die solution does not work. The difference between the inner edge of the end of the branch pipe and the inner edge of the punched hole is so large that internal welding is not possible and external welding does not give acceptable results in terms of flowability.

[0009] It is an object of the present invention to provide a method and apparatus whereby the mechanical steps for making the components of a T-junction can be carried out as a "dry process" that does not require cutting oils or cleaning, and whereby a hole can be made in the main pipe to which a branch of the same size or approximately the same size as the pipe can be connected.

[0010] The method according to the invention comprises the steps of mechanically cutting a hole in the main pipe (T) and a corresponding arc of the main pipe at the end of the branch pipe (P) by removing one solid part from the hole and two solid parts from the end of the branch pipe in a dry mechanical process, while the cleanliness of the joint remains suitable for welding, the method also comprises the steps of punching a hole in the branch pipe with a punch tool moved tangentially to the main pipe beyond the central axis of the main pipe, supporting the main pipe from the inside on both sides of the hole to be cut using an expandable inner support, positioning the shaped end of the branch pipe (P) around the hole in the main pipe and welding the seam between the pipes with an internal weld without using weld filler.

[0011] Examples of methods and devices for performing internal welding are given in publications US6433307(B1), EP1633520(B1) and WO2019166689. Based on these, a person skilled in the art knows how to utilize the present invention for internal welding functions. Summary of the Invention

[0012] In the device according to the invention, a specially designed inner support is used to prevent deformation of the main pipe, such as buckling, when the punch tool penetrates tangentially through the wall of the main pipe. The features of the device are given in claim 5.

[0013] Furthermore, it is an object of preferred embodiments of the present invention to provide a method and an apparatus in which the shape of the bore of the main pipe can be joined as closely as possible to the shape of the inner surface of the end of the branch pipe, and further, the thickness of the overlapping material at the joining seam is suitable for welding joining the parts from the inside without introducing a filler material from the outside.

[0014] These and further objects are achieved according to the invention by the characteristic features set out in the dependent method and apparatus claims.

[0015] If the diameter of the branch pipe is equal or almost equal to the diameter of the main pipe, it is preferable to shape the cutting edge of the punch tool so that it consists of a circular arc and two straight lines located between the arcs. This allows the shape of the hole to be as close as possible to the shape of the inner surface of the end of the branch pipe. In such a case, the contact surface of the two pipes has a thickness of the entire wall thickness of the pipes. Moreover, at the inner edge of the punched hole, an area of ​​material with an acute angle is left, which has an almost uniform thickness on the sides of the hole at the opposite positions of the punch tool and is smaller on the sides of the hole that are far from each other in the longitudinal direction of the main pipe. This material serves as a filler for the internal weld. As a result, there is no material thinner than the base material at the joint. Moreover, the joint made with the internal weld has good flowability. [Brief description of the drawings]

[0016] The invention will now be described by way of an exemplary embodiment with reference to the accompanying drawings, in which:

[0017] [Figure 1] FIG. 1 shows an axonometric assembly view, obliquely from above, of the basic components of the apparatus used to carry out the method according to the present invention. [Figure 2A] FIG. 2A is a longitudinal cross-sectional view of a punch tool according to a preferred embodiment of the present invention. [Figure 2B] FIG. 2B is a top view of the punch tool of FIG. 2A. [Figure 2C] FIG. 2C is a view of the punch tool of FIG. 2A from the cutting blade end. [Diagram 3] FIG. 3 shows a T-junction manufactured using the method and apparatus of the present invention. [Figure 4] FIG. 4 shows in more detail a T-junction pipe manufactured using the method and apparatus of the present invention, with the cross-section shown to the left of the centerline rotated 90 degrees to the right. [Diagram 5] FIG. 5 is a cross-sectional view of the inner support in a supporting position within the main pipe. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The branch hole 20 is punched out in the main pipe T with a punch tool 1 having a substantially circular cross section. The cutting blade 3 of the punch tool 1 has a curved tip 3a and straight cutting blades on both sides of it. The angle β1 between the straight cutting blades on both sides of the curved tip 3a of the cutting blade 3 is 97-107° when viewed in the direction of the movement axis A of the punch tool (FIG. 2C). In the illustrated embodiment, the outer surface of the blade body 2 has two planar side surfaces 18 that end in straight cutting edges of the cutting blade 3. As mentioned above, this design of the punch tool allows the shape of the hole to be as close as possible to the shape of the inner surface of the head of the branch pipe when the branch pipe and the main pipe are of the same size. In such a case, internal welding without a filler material will provide the desired wall thickness at the weld seam. If the size of the branch pipe becomes smaller relative to the main pipe, the planar side surfaces 18 and straight cutting edges will disappear and the blank of the punch tool may become cylindrical. The half of the punch tool that does not participate in the formation of the hole can be shaped relatively freely.

[0019] The tube is supported from the outside during punching by retaining jaws 4, 5. The retaining jaws 4, 5 contain support grooves 6, 8 for receiving the tube to be punched. The curvature of the support grooves matches the curvature of the outer surface of the main tube T. In the position to support the main tube, the retaining jaws 4 and 5 remain slightly spaced apart from each other. The second retaining jaw 5 can be moved back and forth such that the tube is positioned between the retaining jaws 4 and 5 with it being clamped by the grooves 6 and 8.

[0020] The first part 4 of the holding jaw receives the punch tool 1 and contains a punch tool guide hole 7 with a longitudinal axis parallel to the movement direction of the punch tool 1. The punch tool guide hole 7 is elongated and intersects the support groove 6 of the first part 4 of the holding jaw. The guide hole 7 extends beyond the support groove 8 of the second part 5 of the holding jaw. In this case, the tangent of an imaginary cylinder coinciding with the surfaces of the support grooves 6, 8 in the tube support position lies in the guide hole 7 parallel to the longitudinal axis of the guide hole. In other words, the tangent is tangent to the outer surface of the tube at the position where the branch hole is formed. The punch tool guide hole 7 extends to both sides of the support groove 6 of the first part 4 of the holding jaw.

[0021] The punching device further comprises an inner support 9, which supports the main tube T from the inside during punching. The inner support is necessary to prevent the main tube from buckling in advance in a cutting situation when the punch tool penetrates the wall. The inner support 9 must support the tube close to the outer surface of the punch tool. That is, the distance between the arc of the outer edge of the punch tool and the arc of the inner support must be minimal. A round inner support does not allow this. The inner diameters of the different main tubes are not standard. The inner support must also fit tubes with negative tolerances, which would create gaps in other tubes. In the present invention, this problem is solved by designing an inner support that is expandable by means of wedges. Figure 5 shows how the roundness of the inner support is modified on the cutting side at point D, so that the impact point with the inner surface of the tube T is located at point C, which is functionally clear from the line of the path of the cutting edge of the punch tool 1. The inner support 9 is pressed against the inner surface of the main tube by the wedge 11 at the impact point C. The point of impact C with the inner surface of the main tube, as viewed in the direction of movement of the punch tool 1, coincides with the opposing ends of the curved recess 10 of the inner support.

[0022] The inner support 9 is arranged to be moved towards and away from the support position by a single actuator F arranged to initially move the inner support 9 together with the wedge 11 to the support position via the wedge arm 11a and the spring 14. The force required for this movement is less than that required to deform the spring 14 against the spring force (compressing a compression spring), the spring 14 acting like a fixed pin pushing the support flange 12 of the inner support 9 forward. The wedge arm 11a is attached to a push flange 13 which is moved back and forth by the actuator F. The actuator F is usually a piston-cylinder device. In the illustrated example, two compression springs 14 are attached between the support flange 12 and the push flange 13. When the support flange 12 comes into contact with a fixed abutment (not shown) in the frame, the actuator F moves only the wedge 11 via the wedge arm 11a against the biasing force of the spring 14. In this case, the inner support 9 is held in the supporting position by the supporting flange 12, which wedges the inner support 9 in the supporting position. The wedge 11 has a slot 17 into which the pin of the inner support extends. By means of the slot 17 and the pin, the wedge can pull the inner support backwards out of the supporting position. During the wedging step, the slot 17 does not restrict the movement between the inner support 9 and the wedge 11, which continues until the inner support is supported with sufficient force against the inner surface of the tube. The punch tool 1 moves through the curved recess 10 of the inner support 9 when the inner support 9 is in the supporting position in the tube.

[0023] The cutting blade 3 of the punch tool 1 has a curved tip 3a and straight cutting edges on both sides thereof, and the blade 3 is chamfered so that the chamfer angle α with respect to the normal plane (P) of the center line (A) of the punch tool is greater than 0°. In this case, the curved tip 3a of the cutting blade penetrates the tube from the side first when punching.

[0024] The chamfer and shape of the cutting blade 3 of the punch tool 1 are selected so that the cut length is minimized while the small pieces are removed from the tube with a slit-like kerf. The chamfer angle α of the tip of the punch tool and also of the cutting blade 3 is typically between 5° and 30° with respect to the normal plane P of the center line A of the punch tool. The normal plane P is a plane passing through the tip 3a of the cutting blade 3 perpendicular to the center line A of the punch tool. The optimal chamfer bevel angle α depends on the material of the tube to be drilled and the dimensions and size of the hole to be drilled. In many cases, the preferred chamfer angle α is in the order of 10° to 25°, preferably 15° to 20°. As can be seen in the plan view of FIG. 2B, the angle β between the straight part of the cutting blade 3 opposite the curved tip 3a of the cutting blade is typically between 15° and 25°, depending on the magnitude of the angle α. This is also influenced by the angle β1 between the curved tip 3a of the cutting blade and the straight edge of the cutting blade 3 opposite the flat side surface 18, which is typically between 97° and 107° when viewed in the direction of the longitudinal axis (A) of the punch tool (FIG. 2C). This design improves the durability of the punch tool and ensures an optimal material distribution at the edge of the hole for internal welding without the need to introduce filler material from the outside.

[0025] Preferably, the punch tool 1 has a valley-shaped blade body 2 that terminates in a cutting blade 3. The outer surface of the blade body 2 has two planar side faces 18 that terminate in a straight cutting edge of the cutting blade. The remaining part of the outer surface of the blade body 2 may be cylindrical. The wall thickness of the blade body 2 increases from the cutting blade 3 towards the base of the blade body 2. The base of the blade body 2 ends in a relieving pit 15 that receives the chips removed from the tube. The punch tool 1 together with its cutting blade is manufactured, for example, by cutting a cylindrical punch tool blank with planar side faces 18 at an angle of about 15-25°, so that the tip of the punch tool is formed in the shape shown in FIG. 2B, with a circular arc tip in the center and straight cutting edges on both sides. Such a shape can reduce the punch force and improve the durability of the punch tool. FIG. 2B shows the elliptical arc (dash-dotted line) formed by a chamfer cut when the punch tool is round. In this case, the impact point with the tube wall surface is too obtuse. The cutting edge is straight, so the impact point is sharp. The tip 3a of the cutting blade 3 is positioned so that it penetrates the tube from the side first when punching. This prevents the tube from rotating as the punch tool 1 pushes out, and reduces the clamping force of the holding jaws 4, 5 against the outer circumferential surface of the tube.

[0026] To form branch holes in the tube, the punch tool 1 is guided by means of the guide hole 7 to move tangentially to the tube between the outer circumferential surface and the center line of the tube. Tangential here means that the tangent of the tube parallel to the movement direction of the punch tool is located inside the punch tool 1. In other words, the punch tool is moved tangentially to the main tube beyond the central axis of the main tube. In this case, the cutting blade 3 of the punch tool first penetrates the tube at one edge of the hole formed from the outside to the inside of the tube, and then penetrates the tube at the other opposite edge of the hole formed from the inside to the outside of the tube. During punching, the cutting blade 3 of the punch tool cuts the side of the hole 20 with the opposite side of the punch tool.

[0027] 4 shows how the end of the branch pipe P is shaped to be optimally connected by an internal weld to the hole 20 formed as described hereinbefore. The cut depth of the part removed from the end of the branch pipe P is adjusted to provide an uncut, straight outer end surface 23 at the end of the branch pipe between the corresponding arcs of the main pipe, thereby allowing an optimal amount of material at the joint to be melted during welding.

[0028] Using the above described device, the main pipe can be perforated in the following method steps: - inserting the main pipe (T) axially between the holding jaws 4, 5 up to the drilling position of the main pipe; - fixing the holding jaws 4, 5 on the main pipe and holding the main pipe in a drilling position; - moving the inner support 9 and the wedge 11 located in the inner support within the main pipe; - stopping the movement of the inner support 9 in a position such that the curved recess 10 of the inner support 9 is located on the path of the punch tool 1 of the hole to be made in the main tube; - continuing the movement of the wedge 11 relative to the inner support 9 in order to press the inner support against the inner wall of the main tube (T) on both sides of the recess 10; - guiding the punch tool 1 to move tangentially relative to the tube between the outer circumferential surface and the centerline of the tube, such that a tangent of the tube parallel to the movement direction of the punch tool is located inside the punch tool 1, so that the cutting blade 3 of the punch tool first penetrates the main tube at one edge of the hole formed from the outside to the inside of the main tube, and then penetrates the main tube at the opposite edge of the hole formed from the inside to the outside of the main tube; - moving the wedge 11 in a direction opposite to the previous direction of movement, thereby releasing the inner support 9 from pressure against the inner surface of the main tube; - moving the inner support 9 and the wedge 11 outside the main pipe; - opening the holding jaws 4, 5 and allowing the perforated main pipe to fall into a collection container. The perforated tube must be removed from the holding jaws 4 using a special remover (not shown).

[0029] Thus, the punch tool is used to remove one solid part from the wall of the main pipe directly to the outside of the pipe. Two curved pieces are also removed from the end of the branch pipe P by punching, and the curvature of the cut surface of the two curved pieces matches the curvature of the outer surface of the main pipe. Finally, the shaped end of the branch pipe (P) is placed around the hole 20 of the main pipe, and the joint 21 between the pipes is welded with an internal weld by fusing the material at the overlapped joint ends without using a weld filler. In FIG. 3, an electrode arm 24 and an electrode 25 are shown, whose tip is guided along a path along the joint 21 by rotating the electrode arm while moving it back and forth. A power supply 26 is used to generate a voltage between the electrode 25 and the pipe. The voltage is adjusted to a suitable level so that the electric arc between the electrode 25 and the joint fuses the material of the joint 21 into an integral wall joining the walls of the pipes T and P.

Claims

1. 1. A method of making a pipe T-junction by connecting a shaped end of a branch pipe to an edge of a bore of a main pipe by internal welding, comprising: The method is: mechanically cutting the hole in the main pipe (T) and the corresponding arc in the end of the branch pipe (P) by removing one solid part from the hole and two solid parts from the end of the branch pipe in a dry mechanical process; The cleanliness of the joint remains suitable for welding, The method also punching a branch pipe hole with a punch tool (1) moved tangentially to the main pipe beyond the central axis of the main pipe; supporting the main tube from the inside on both sides of the hole to be cut using expandable internal supports (9, 10, 11); placing the shaped end of the branch pipe (P) around the bore (20) of the main pipe and welding the joint (21) between the pipes with an internal weld without the use of weld filler material.

2. The hole in the main pipe is - axially inserting the main pipe (T) between the holding jaws (4, 5) up to the position of the piercing of the main pipe; - fixing the holding jaws (4, 5) to the main pipe in order to hold it in the drilling position; - moving the inner support (9) and the wedge (11) in the inner support in the main pipe; - stopping the movement of the inner support (9) in a position such that the curved recess (10) of the inner support is located on the path of the punch tool (1) of the hole to be made in the main pipe; - continuing the movement of the wedge (11) relative to the inner support (9) in order to press the inner support against the inner wall of the main tube (T) on both sides of the recess (10); - guiding the punch tool (1) to move tangentially relative to the tube between its outer circumferential surface and its centre line, so that a tangent of the tube parallel to the movement direction of the punch tool is located inside the punch tool (1), so that a cutting blade (3) of the punch tool penetrates the main tube first at one edge of a hole made from the outside to the inside of the main tube, and then at the opposite edge of a hole made from the inside to the outside of the main tube; - moving the wedge (11) in a direction opposite to the previous direction of movement, relieving the inner support (9) from pressure against the inner surface of the main tube; - moving the inner support (9) and the wedge (11) outside the main pipe; - opening the holding jaws (4, 5) and allowing the perforated main pipe to fall into a collection container; Opened by, The method of claim 1.

3. The cutting depth of the part removed from the end of the branch pipe (P) is adjusted to provide an uncut straight end surface (23) at the end of the branch pipe between the arcs corresponding to the main pipe; The method according to claim 1 or 2.

4. An inner support (9) is pressed against the inner surface of the tube by a wedge (11), The wedge is moved back and forth relative to the inner support (9) by the same actuator (F) that moves the inner support (9) to and from the supporting position; the inner support (9) together with its wedge (11) is first moved into the supporting position via the wedge arm (11a) and the spring (14) and then moved into the supporting position by moving only the wedge (11) via the wedge arm (11a) against the biasing force of the spring (14); The method of claim 2.

5. 3. An apparatus for producing a branch hole in a pipe by the method of claim 2, comprising: The device is A punch tool (1) having a circular, nearly circular or partially circular cross section, a cutting blade (3) at the end of the punch tool; holding jaws (4, 5) for supporting the tube from the outside during punching, the holding jaws (4, 5) including support grooves (6, 8) for receiving the tube to be punched; a guide hole (7) for receiving the punch tool (1) in the first part (4) of the holding jaw; Including, The guide hole (7) has a longitudinal axis parallel to the direction of movement of the punch tool (1), the guide hole (7) is elongated, intersecting the support groove (6) at the first portion (4) of the holding jaw and extending beyond the support groove (8) at the second portion (5) of the outer support; the tangent of an imaginary cylinder which coincides with the surface of the support groove (6, 8) at the tube support position is located in the guide hole (7) parallel to the longitudinal axis of the guide hole; The punch tool guide hole (7) extends to both the side of the support groove (6) of the first part (4) of the outer support and the inner support (9) for supporting the tube from the inside during punching; The inner support (9) includes a wedge (11) configured to press the inner support (9) against the inner surface of the tube; the inner support (9) includes a curved recess (10) configured to receive the punch tool (1) therethrough when the inner support (9) is placed in the tube in the supporting position; the inner support (9) is shaped so that its point of impact (C) with the inner surface of the main pipe coincides with the opposing ends of the curved recess (10) as viewed in the direction of movement of the punch tool (1); Device.

6. The blade (3) is chamfered such that the chamfer angle (α) is greater than 0° with respect to the normal plane (P) of the center line (A) of the punch tool, and the curved tip (3a) of the cutting blade penetrates the tube from the side first during punching.

6. The apparatus of claim 5.

7. the chamfer angle (α) of the cutting blade (3) relative to the normal plane (P) of the center line (A) of the punch tool is between 5° and 30°; 6. The apparatus of claim 5.

8. The cutting blade (3) of the punch tool (1) has a curved tip (3a) and straight cutting edges on both sides thereof; the angle (β1) between the straight cutting edges of the cutting blade (3) opposite the curved tip (3a) of the cutting blade (3) is between 97° and 107°, as seen in the direction of the longitudinal axis (A) of the punch tool; 7. The apparatus of claim 6.

9. The cutting blade (3) of the punch tool (1) has a curved tip (3a) and straight cutting edges on both sides thereof, the angle (β1) between the straight cutting edges of the cutting blade (3) opposite the curved tip (3a) of the cutting blade (3) is between 97° and 107°, as seen in the direction of the longitudinal axis (A) of the punch tool; 8. The apparatus of claim 7.

10. A punch tool (1) having a valley-shaped blade body (2) terminating in a cutting blade (3), The outer surface of the blade body (2) has two planar sides (18) that terminate in a linear cutting edge of the cutting blade. An apparatus according to any one of claims 5 to 9.

11. The thickness of the blade body (2) increases from the cutting blade (3) toward the base of the blade body (2); The base of the blade body (2) terminates in a relief hole (15) for receiving debris removed from the main pipe.

6. The apparatus of claim 5.

12. The inner support (9) First, the inner support (9) together with the wedge (11) is moved into a supporting position via the wedge arm (11a) and the spring (14); then, when the inner support is held in the supporting position, it is arranged to move towards and away from the supporting position by a single actuator (F) arranged to move only the wedge (11) via the wedge arm (11a) against the biasing force of the spring (14); The inner support (9) is thereby wedged into the supporting position.

6. The apparatus of claim 5.

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