Method and apparatus for creating a T-shaped pipe junction

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 formed end of a branch pipe to the edge of a hole in a main pipe by internal welding.

[0002] Another object of the present invention is an apparatus that can be used for drilling holes in the main pipe, which is required in this method.

[0003] The end of the branch pipe is cut in an arc shape that matches the main pipe using, for example, the methods and apparatus known from Patent Publication US10537948. However, the cutting depth of the part removed from the end of the branch pipe (P) is adjusted to provide a linear end face that is not cut at the end of the branch pipe between the arcs corresponding to the main pipe, as shown in FIG. 4. Thereby, an appropriate amount of material can be left on the outer surface of the main pipe, and the parts can be welded from the inside without introducing a filler from the outside.

Background Art

[0004] [[ID=......]] When branching a pipe into a T-shape, there are many methods for making a hole for the branch connection. In the case of a small pipe, the most common method is drilling. Since chips are produced when drilling a hole, it is necessary to use a cutting fluid to drill the hole efficiently. The chips and the cutting fluid are disadvantageous both in terms of production and the environment. For joint welding, the chips must be removed and the parts must be cleaned, usually with warm water. Furthermore, drilling a hole in a pipe is a relatively time-consuming production method.

[0005] CA2280650 discloses a method for punching holes in a curved pipe of an engine exhaust manifold. The punching tool is guided so that the outside of the tool is in contact with the outer surface of the pipe. The punched holes are widened using a mandrel with segmented fingers. Finally, threads are provided for attaching a metal pipe with a sensor. Due to the design of the tip of the punching tool and the lack of internal support, it is not possible to punch holes suitable for creating T-branches. The shape of the resulting holes is not suitable for connecting the formed ends of branch pipes by internal welding.

[0006] Japanese Patent Publication No. 2001162335 discloses a method for punching a hole in a pipe such that a punch tool tangentially penetrates a portion of the pipe's outer circumference and removes material pushed by the flat front end of the blade from the pipe's outer circumference. The chamfered portion of the blade expels the removed material from the hole. The shape of the blade upsets the material being removed and causes deformation of the pipe, particularly because the non-expandable inner support does not adequately support the edge of the hole at the point of impact of the punch tool. The hole thus formed is unsuitable for connecting the formed ends of branch pipes by internal welding. This is especially true when the diameter of the branch pipe is large, as the described method is not suitable for forming holes with a diameter close to the diameter of the pipe being punched. This unsuitability stems from the fact that the shape of the blade is deformable and the non-expandable inner support does not prevent deformation of the pipe.

[0007] US Patent No. 3120143 discloses a method for punching holes in a pipe tangentially to connect T-junctions. The cutting blade of the punch tool first penetrates the pipe from the outside to the inside at one edge of the hole formed, and then penetrates from the inside to the outside at the opposite edge of the hole formed. The punch 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 steel pipes of typical wall thickness. Also, because the support force inside the pipe is weak, the pipe deforms, making it unsuitable for the manufacture of T-junction fittings.

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

[0009] The object of the present invention is to provide a method and apparatus for manufacturing T-shaped branch components as a "dry process" that does not require cutting oil or cleaning, and for providing a hole in the main pipe that can connect a branch of the same size as or approximately the same size as the main pipe.

[0010] The method according to the present invention includes the step of mechanically cutting a hole in a main pipe (T) and an arc corresponding to the main pipe at the end of a branch pipe (P) by a dry mechanical process, by removing one solid piece from the hole and two solid pieces from the end of the branch pipe, such that the cleanliness of the joint remains suitable for welding. The method also includes the step of punching a hole in the branch pipe with a punch tool moved tangentially to the main pipe across 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 internal support; positioning the formed end of the branch pipe (P) around the hole in the main pipe; and welding the joint between the pipes by internal welding without using welding filler.

[0011] Examples of methods and apparatus for performing internal welding are presented in publications US6433307(B1), EP1633520(B1), and WO2019166689. Based on these, those skilled in the art are aware of ways to utilize the present invention with respect to internal welding functionality. [Overview of the Initiative]

[0012] In the apparatus according to the present invention, a specially configured inner support is used to prevent deformation of the main pipe, such as buckling, when the punch tool penetrates the wall of the main pipe in a tangential direction. The features of this apparatus are shown in claim 5.

[0013] Furthermore, an object of a preferred embodiment of the present invention is to provide a method and apparatus that allows the shape of the hole in the main pipe to be joined as closely as possible to the shape of the inner surface of the end of the branch pipe, and furthermore, the thickness of the overlapping material at the joint is suitable for welding the parts together from the inside without introducing filler from the outside.

[0014] These additional objectives are achieved by the present invention through the characteristic features set forth in the claims of the dependent methods and apparatus.

[0015] When the diameter of the branch pipe is equal to or approximately 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 an 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 the same thickness as the entire wall thickness of the pipes. Furthermore, a region of acute-angled material remains on the inner edge of the punched hole, with a nearly uniform thickness on the sides of the hole at opposing positions on the punch tool, and smaller on the sides of holes that are separated from each other in the longitudinal direction of the main pipe. This material functions as a filler for internal welding. As a result, there is no material thinner than the base material in the joint. Furthermore, the joint created by internal welding has good fluidity. [Brief explanation of the drawing]

[0016] Next, the present invention will be described with reference to the attached drawings, using exemplary embodiments.

[0017] [Figure 1] Figure 1 shows an unequal-angled assembly diagram of the basic components of the apparatus used to carry out the method according to the present invention, viewed from above at an oblique angle. [Figure 2A] Figure 2A is a longitudinal cross-sectional view of a punch tool according to a preferred embodiment of the present invention. [Figure 2B] Figure 2B is a top view of the punch tool shown in Figure 2A. [Figure 2C] Figure 2C shows the punch tool from Figure 2A, viewed from the end of the cutting blade. [Figure 3] Figure 3 shows a T-shaped branch pipe manufactured using the method and apparatus according to the present invention. [Figure 4] Figure 4 shows in more detail a T-shaped branch pipe manufactured using the method and apparatus according to the present invention, with the cross-sectional view rotated 90 degrees to the right shown to the left of the centerline. [Figure 5] Figure 5 is a cross-sectional view of the inner support located in a support position within the main tube. [Modes for carrying out the invention]

[0018] The branch hole 20 is punched into the main pipe T using a punch tool 1 with 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 either side of the curved tip 3a of the cutting blade 3 is 97 to 107° when viewed in the direction of the motion axis A of the punch tool (Figure 2C). In the illustrated embodiment, the outer surface of the blade body 2 has two planar sides 18 that end with the straight cutting edges of the cutting blades 3. As described above, this design of the punch tool allows the shape of the hole to be made as close as possible to the shape of the inner surface of the leading edge of the branch pipe when the branch pipe and the main pipe are the same size. In such cases, the desired wall thickness can be obtained at the weld joint with internal welding without the use of filler. When the size of the branch pipe is smaller than that of the main pipe, the planar sides 18 and straight cutting edges are eliminated, and the blank of the punch tool may become cylindrical. The half of the punch tool that does not participate in hole formation can be shaped relatively freely.

[0019] The pipe is supported from the outside by retaining jaws 4 and 5 during punching. The retaining jaws 4 and 5 include support grooves 6 and 8 for receiving the pipe to be punched. The curvature of the support grooves matches the curvature of the outer surface of the main pipe T. In the position supporting the main pipe, retaining jaws 4 and 5 remain slightly separated from each other. The second retaining jaw 5 can be moved back and forth so that the pipe is positioned between retaining jaws 4 and 5, clamped and held by grooves 6 and 8.

[0020] The first portion 4 of the retaining jaw receives the punch tool 1 and includes a punch tool guide hole 7 having a longitudinal axis parallel to the direction of movement of the punch tool 1. The punch tool guide hole 7 is elongated and intersects with the support groove 6 of the first portion 4 of the retaining jaw. The guide hole 7 extends beyond the support groove 8 of the second portion 5 of the retaining jaw. In this case, the tangent of a virtual cylinder that coincides with the surfaces of the support grooves 6, 8 at the pipe support position is located within the guide hole 7, parallel to the longitudinal axis of the guide hole. In other words, the tangent is in contact with the outer surface of the pipe 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 portion 4 of the retaining jaw.

[0021] The punching device further includes an inner support 9 that supports the main pipe T from the inside during punching. The inner support is necessary to prevent the main pipe from buckling in advance during the cutting process when the punch tool penetrates the wall. The inner support 9 needs to support the pipe 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 minimized. This cannot be done with a round inner support. The inner diameters of different main pipes are not standard. The inner support must also fit pipes with negative tolerances, leaving gaps in other pipes. In this invention, this problem is solved by designing an inner support that can be expanded by a wedge. Figure 5 shows how the curvature of the inner support is modified on the cutting side at point D so that the point of impact with the inner surface of pipe T is located at point C, which has functional clearance from the path line of the cutting edge of the punch tool 1. The inner support 9 is pressed against the inner surface of the main pipe by the wedge 11 at the point of impact C. The point of collision C with the inner surface of the main pipe coincides with the opposing ends of the curved recess 10 of the inner support, as viewed from the direction of movement of the punch tool 1.

[0022] The inner support 9 is arranged to move towards or away from the support position by a single actuator F initially arranged to 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 smaller than the force required to deform the spring 14 against the spring force (compress the compression spring), and the spring 14 acts like a fixed pin that pushes out the support flange 12 of the inner support 9. The wedge arm 11a is attached to a push flange 13 that 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 contacts a fixed abutment (not shown) within 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 support position by the support flange 12, whereby the inner support 9 is wedged in the support position. The wedge 11 has a slot 17 in which a pin of the inner support extends. The slot 17 and the pin allow the wedge to pull the inner support backward from the support position. During the wedging step, the slot 17 does not limit the movement between the inner support 9 and the wedge 11, and this movement continues until the inner support is supported against the inner surface of the tube with sufficient force. The punch tool 1 moves through the curved recess 10 of the inner support 9 when the inner support 9 is in the support position within 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 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. In this case, the curved tip 3a of the cutting blade penetrates the tube first from the side of the tube during punching.

[0024] The chamfer and shape of the cutting blade 3 of the punch tool 1 are selected such that the cutting length is minimized and small pieces are removed from the pipe by a slit-like cut. The tip of the punch tool and likewise the chamfer angle α of the cutting blade 3 are usually 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 optimum chamfer opening angle α depends on the material of the pipe to be drilled, the dimensions and size of the hole to be drilled. In many cases, the preferred chamfer angle α is about 10° to 25°, preferably about 15° to 20°. As seen in the plane of FIG. 2B, the angle β between the straight portions of the cutting blade 3 on the opposite side of the curved tip 3a of the cutting blade is typically between 15° and 25°, although it depends on the magnitude of the angle α. This is also affected by the angle β1 between the curved tip 3a of the cutting blade and the straight cutting edge of the cutting blade 3 on the opposite side of the planar side surface 18, and is typically between 97° and 107° when viewed in the direction of the longitudinal axis (A) of the punch tool. (FIG. 2C). This design can improve the durability of the punch tool and make the material distribution at the edge of the hole optimal for internal welding without introducing a filler material from the outside.

[0025] Preferably, the punch tool 1 has a valley-shaped blade body 2 that terminates with a cutting blade 3. The outer surface of the blade body 2 has two planar sides 18 that terminate with the straight cutting edge of the cutting blade. The remaining part of the outer surface of the blade body 2 may be cylindrical. The 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 with a relief pit 15 that receives the small pieces removed from the pipe. The punch tool 1, along with its cutting blade, is manufactured, for example, by cutting a cylindrical punch tool blank with planar sides 18 at an angle of about 15 to 25°, thereby forming the tip of the punch tool into the shape shown in Figure 2B, which has an arc-shaped tip in the center and straight cutting edges on both sides. This shape can reduce the punching force and improve the durability of the punch tool. Figure 2B shows an elliptical arc (dotted line) formed by a chamfer cut when the punch tool is round. In this case, the point of impact with the pipe wall is too obtuse. Because the cutting edge is straight, the point of impact is sharp. The tip 3a of the cutting blade 3 is positioned to penetrate the pipe first from the side during punching. As a result, the tip 3a prevents the pipe from rotating as the punching tool 1 pushes out, and the clamping force of the retaining jaws 4 and 5 against the outer surface of the pipe can be reduced.

[0026] To form a branch hole in the pipe, the punch tool 1 is guided by a guide hole 7 to move tangentially to the pipe between the outer surface and the centerline of the pipe. Here, tangential means that the tangent of the pipe parallel to the direction of movement of the punch tool is located inside the punch tool 1. In other words, the punch tool is moved tangentially to the main pipe, across the central axis of the main pipe. In this case, the cutting blade 3 of the punch 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 other opposite edge of the hole formed from the inside to the outside of the pipe. Between punches, the cutting blade 3 of the punch tool cuts the sides of the hole 20 with the opposing sides of the punch tool.

[0027] Figure 4 shows how the end of the branch pipe P is shaped to be optimal for internal welding connection to the hole 20 formed as described above. 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. This allows for an optimal amount of material to be melted at the joint during welding.

[0028] Using the apparatus described above, a hole can be made in the main pipe in the following method steps: - A step of inserting the main pipe (T) axially between the retaining jaws 4 and 5 until the drilled position of the main pipe; - The step of fixing the retaining jaws 4 and 5 to the main pipe and holding the main pipe in the drilling position; - A step of moving the inner support 9 and wedge 11 located within the inner support within the main tube; - A step of stopping the movement of the inner support 9 at a position where the curved recess 10 of the inner support 9 is positioned on the path of the punching tool 1 for the hole formed in the main pipe; - The step of 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; - The punch tool 1 is guided to move tangentially to the pipe between the outer surface and the center line of the pipe, such that the tangent of the pipe parallel to the direction of movement of the punch tool is located inside the punch tool 1, thereby causing the cutting blade 3 of the punch tool to first penetrate the main pipe at one edge of a hole formed from the outside to the inside of the main pipe, and then penetrate the main pipe at the opposite edge of a hole formed from the inside to the outside of the main pipe; - Move the wedge 11 in the opposite direction to the previous direction of movement, thereby releasing the inner support 9 from the pressure against the inner surface of the main tube; - Step of moving the inner support 9 and wedge 11 to the outside of the main tube; - The step of opening the holding jaws 4 and 5 and dropping the perforated main tube into the recovery container. The perforated tube must be removed from the retaining jaw 4 using a special removal tool (not shown).

[0029] Therefore, the punching tool is used to remove one solid piece directly from the wall of the main pipe 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 surfaces of the two curved pieces matches the curvature of the outer surface of the main pipe. Finally, the formed end of the branch pipe (P) is positioned around the hole 20 in the main pipe, and the joint 21 between the pipes is welded by internal welding by fusing the material at the overlapping joint ends without using welding filler. Figure 3 shows an electrode arm 24 and an electrode 25, and by rotating the electrode arm while moving it back and forth, its tip is guided along a path along the joint 21. A power supply 26 is used to generate a voltage between the electrode 25 and the pipe. The voltage is adjusted to an appropriate level so that the electric arc between the electrode 25 and the joint fuses the material of the joint 21, creating a unified wall that joins the walls of pipe T and pipe P.

Claims

1. A method for creating a T-shaped pipe branch by connecting the formed end of a branch pipe to the edge of a hole in the main pipe by internal welding, The method is, The process involves mechanically cutting the hole in the main pipe (T) and the corresponding arc at the end of the branch pipe (P) by removing one solid piece from the hole and two solid pieces from the end of the branch pipe in a dry mechanical process. The steps include: creating a hole in a branch pipe with a punch tool (1) that moves tangentially to the main pipe, beyond the central axis of the main pipe; The steps include supporting the main tube from the inside on both sides of the hole to be cut using expandable inner supports (9, 10, 11), A method comprising the steps of arranging the formed end of a branch pipe (P) around the hole (20) of the main pipe, and welding the joint (21) between the pipes by internal welding without using welding filler.

2. The hole in the main pipe, - The step of inserting the main pipe (T) axially between the retaining jaws (4, 5) until the drilling position of the main pipe; - The step of fixing the retaining jaws (4, 5) to the main pipe in order to hold the main pipe in the drilling position; - A step of moving the inner support (9) and the wedge (11) located within the inner support within the main tube; - A step of stopping the movement of the inner support (9) at a position where the curved recess (10) of the inner support is positioned on the path of the punching tool (1) for the hole formed in the main tube; - The step of 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); - The punch tool (1) is guided to move tangentially to the pipe between the outer surface and the center line of the pipe, such that the tangent of the pipe parallel to the direction of movement of the punch tool is located inside the punch tool (1), thereby causing the cutting blade (3) of the punch tool to first penetrate the main pipe at one edge of a hole formed from the outside to the inside of the main pipe, and then penetrate the main pipe at the opposite edge of a hole formed from the inside to the outside of the main pipe; - The step of moving the wedge (11) in the opposite direction to the previous direction of movement, thereby releasing the inner support (9) from the pressure on the inner surface of the main tube; - The steps of moving the inner support (9) and wedge (11) to the outside of the main tube; - The steps include opening the holding jaws (4, 5) and dropping the perforated main tube into the recovery container, It can be opened by The method according to claim 1.

3. The cutting depth of the portion 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. The inner support (9) is pressed against the inner surface of the tube by the wedge (11), The wedge is moved back and forth relative to the inner support (9) by the same actuator (F) used to move the inner support (9) to and from the support position. The inner support (9), together with its wedge (11), first moves to the support position via the wedge arm (11a) and spring (14), and then moves to the support position by moving only the wedge (11) via the wedge arm (11a) against the biasing force of the spring (14). The method according to claim 2.

5. An apparatus for creating a branch hole in a pipe by the method of claim 2, The device is A punch tool (1) having a circular or partially circular cross-section, The cutting blade (3) at the end of the punch tool, It includes support grooves (6, 8) for receiving the pipe to be punched, and retaining jaws (4, 5) for supporting the pipe from the outside during punching, The first part (4) of the retaining jaw has a guide hole (7) for receiving the punch tool (1), Includes, The guide hole (7) has a longitudinal axis parallel to the direction of movement of the punch tool (1), and the guide hole (7) is elongated, intersects with the support groove (6) at the first part (4) of the retaining jaw, and extends beyond the support groove (8) at the second part (5) of the outer support. The tangent to the virtual cylinder that coincides with the surface of the support groove (6, 8) at the pipe support position is located within 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 portion (4) of the outer support and to 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 such that the punch tool (1) passes through it when the inner support (9) is positioned inside the tube in the support position. The inner support (9) is shaped such that its point of contact (C) with the inner surface of the main tube coincides with the opposing ends of the curved recess (10) when viewed from 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 pipe from the side first during punching. The apparatus according to claim 5.

7. The chamfer angle (α) of the cutting blade (3) with respect to the normal plane (P) of the center line (A) of the punch tool is between 5° and 30°. The apparatus according to 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 edge of the cutting blade (3) on the opposite side of the curved tip (3a) of the cutting blade (3) is between 97° and 107° when viewed in the direction of the longitudinal axis (A) of the punch tool. The apparatus according to 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 edge of the cutting blade (3) on the opposite side of the curved tip (3a) of the cutting blade (3) is between 97° and 107° when viewed in the direction of the longitudinal axis (A) of the punch tool. The apparatus according to claim 7.

10. The punch tool (1) has a valley-shaped blade body (2) that ends with a cutting blade (3), The outer surface of the blade body (2) has two planar sides (18) that terminate at the straight cutting edge of the cutting blade. The apparatus according to any one of claims 5 to 9.

11. The 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 with a relief hole (15) that receives small pieces removed from the main pipe. The apparatus according to claim 10.

12. The inner support (9) is First, the inner support (9) is moved to the support position along with the wedge (11) via the wedge arm (11a) and spring (14). Next, when the inner support is held in the support position, a single actuator (F) is positioned to move only the wedge (11) via the wedge arm (11a) against the biasing force of the spring (14), and is positioned to move toward and away from the support position. As a result, the inner support (9) is wedge-secured to the support position. The apparatus according to claim 5.

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