Method for calibrating the dimensions of a T-branch pipe and device for carrying it out

Abstract

The present invention relates to a method and device for calibrating the dimensions of a T-branch pipe (1). The T-branch pipe includes a standard pipe (2) and a collar (3) forming a branching opening, the collar (3) being larger than the desired final dimension in the longitudinal direction (x) of the standard pipe (2) and smaller than the desired final dimension in the transverse direction. The collar (3) is flared out by a first calibration force (F1) in one direction perpendicular to the longitudinal direction (x) of the standard pipe (2). The standard pipe (2) is locally flared out by a second calibration force (F2) and a third calibration force (F3) in two directions. This flaring out is performed in stages so that the three calibration forces (F1, F2, F3) act simultaneously. When the calibration forces (F1, F2, F3) act, the standard pipe (2) is contracted near its both ends by a fourth force (F4) acting parallel to the axial direction (y) of the collar (3).

Description

[Technical Field]

[0001] The present invention relates to a method for calibrating the dimensions of a T-branch pipe, the T-branch pipe including a standard pipe and a collar forming a branch opening, the collar diameter being larger than the desired final dimension in the longitudinal direction of the pipe and smaller than the desired final dimension in the transverse direction.

[0002] The present invention further relates to an apparatus for carrying out a method for calibrating the dimensions of a T-branch pipe, the T-branch pipe comprising a standard pipe and a collar forming a branch opening, the diameter of the collar being larger than the desired final dimension in the longitudinal direction of the pipe and smaller than the desired final dimension in the transverse direction. [Background technology]

[0003] Such T-branch pipes are produced by stretching a material into a pipe casing to form a branched cylindrical collar. However, the elasticity of the pipe and the internal stresses of the material adversely affect the shape and dimensions of the formed collar and the standard pipe. In particular, when the diameter of the standard pipe and collar is large relative to the wall thickness (e.g., 70 mm or more), dimensional errors and shape defects often occur. Attempts to partially eliminate the adverse effects of the collar forming stage have been made, for example, in patent publication EP 1332807 B1, where a calibration tool is used to affect only the dimensions of the collar.

[0004] In reality, even standard pipes suffer from molding defects and deformations during the collar forming stage. These deformations are exaggerated and illustrated in the accompanying Figure 1. The outline of the finished calibrated T-branch pipe 1 is shown by the dashed lines labeled 2' and 3'. After the collar 3 is formed, the dimensions of the collar 3 itself are larger along the length of the standard pipe than perpendicular to the length of the standard pipe. The stresses induced by the collar 3 on the standard pipe 2 are so great that the standard pipe 2 buckles along the length of the pipe on both sides of the collar 3, and the ends of the standard pipe rise radially upward. The mouth of the standard pipe becomes substantially egg-shaped. Summary of the Invention

[0005] SUMMARY OF THE INVENTION It is an object of the present invention to substantially eliminate the above-mentioned problems arising from the formation of collars.

[0006] In order to achieve the aforementioned object, the method according to the invention is characterized in that the aforementioned flare-out is carried out in stages, in that the collar is flared out by a first calibrated force in one direction, transverse to the longitudinal direction of the standard pipe, and then the standard pipe is locally flared out in two directions by a second and a third calibrated force, so that finally all three calibrated forces act simultaneously.

[0007] Furthermore, an apparatus for carrying out the method according to the invention is characterized in that it comprises a collar calibration mandrel including a first calibration element, by means of which a first calibration force can be applied to the collar transversely to the longitudinal direction of the pipe in order to flare out the collar in a corresponding direction; a standard pipe calibration mandrel including a second calibration element, by means of which a second calibration force can be applied to the standard pipe adjacent to the collar in the axial direction of the collar in order to flare out the standard pipe; and a third calibration element, by means of which a third calibration force can be applied to the standard pipe transversely to the longitudinal direction of the standard pipe in order to flare out the standard pipe, and finally, the flare-out can be performed in stages so that all three calibration forces are applied simultaneously.

[0008] Preferred embodiments of the invention are disclosed in the dependent claims. [Brief explanation of the drawings]

[0009] The present invention will now be described in more detail with reference to the drawings according to preferred embodiments of the invention.

[0010] [Figure 1] FIG. 1 shows the deformation of the T-branch pipe from various angles in an exaggerated manner. [Figure 2] FIG. 2 is a cross-sectional view of a standard pipe and a T-branch pipe with a calibration mandrel for the collar, showing the calibration start point. [Figure 3A] FIG. 3A is a cross-sectional view of FIG. 2 with the collar calibration mandrel lowered relative to the standard pipe calibration mandrel to calibrate the collar with the first calibration member. [Figure 3B] FIG. 3B shows the configuration of FIG. 3A in a longitudinal cross section of a T-branch pipe. [Figure 4] FIG. 4 shows the configuration of FIG. 3B with the second calibration member of the standard pipe calibration mandrel in operation. [Figure 5A] FIG. 5A is a cross-sectional view of the configuration of FIG. 4 showing the third calibration member of the standard pipe calibration mandrel in operation. [Figure 5B] FIG. 5B is a partial enlarged view of the circled portion of FIG. 5A. [Figure 6] FIG. 6 shows an actuator positioned within the standard pipe calibration mandrel to move the second and third calibration members. [Figure 7] FIG. 7 is a side view of the arrangement of FIG. 5B, showing the end plunger in operation. DETAILED DESCRIPTION OF THE INVENTION

[0011] FIG. 1 shows a top view, a side view, and an end view of a T-branch pipe designated by reference numeral 1. The T-branch pipe shown in FIG. 1 is provided with a collar 3 formed by the edge of a hole drilled in a standard pipe 2, which has not yet been calibrated according to the present invention. Therefore, the deformations resulting from the formation of the collar 3, as already described above, are visible in FIG. 1. It should also be noted that the deformations shown in FIG. 1 are exaggerated to better illustrate the concept of the present invention. Furthermore, it should be noted that at this stage, the diameter of the collar is larger than the desired final size in the direction of the longitudinal axis x of the standard pipe 2 and smaller than the desired final size transversely of the longitudinal axis x. The longitudinal oversizing is intentional, while the transverse undersizing is an unavoidable consequence of the operating principle of the collaring device.

[0012] Figures 2, 3A, and 3B illustrate an apparatus for carrying out the present invention. Figure 2A shows a cross section of a T-branch pipe 1 supported on a support element 24. The collar 3 of the T-branch pipe 1 is preferably oriented so that its longitudinal axis y is substantially vertical (at a 90° angle relative to the longitudinal axis x of the standard pipe 2) and so that its mouth opens upward. The apparatus includes an elongated calibration mandrel 11 fitted into the space defined by the standard pipe 2. The standard pipe calibration mandrel 11 is inserted into the standard pipe 2 along its longitudinal axis x, which is perpendicular to the y-axis. The calibration mandrel 11 has a substantially circular cross section and a slightly smaller diameter than the standard pipe 2. Over a portion of its longitudinal distance, the calibration mandrel 11 is formed with surfaces 12 and 13 that are chamfered relative to a plane passing through the y-axis. These surfaces are formed, for example, by milling the surface of the calibration mandrel 11. The surfaces 12 and 13 are formed on the upper part of the calibration mandrel. The calibration mandrel 11 is positioned along its longitudinal axis x so that the chamfered surfaces 12 and 13 are positioned in the opening of the collar 3. The remaining structure and operation of the calibration mandrel 11 is described in more detail below.

[0013] 2 and 3A show a calibration mandrel 4 of a collar 3, which is configured so that it can be moved by a transfer means 10 over a portion of the distance in the y-axis direction in the direction of arrow A shown in FIG. 2, in the manner shown in FIG. 3A, relative to a calibration mandrel 11 inserted into the standard pipe 2 through an opening in the collar 3. FIG. 3B is a side view of the state according to FIG. 3A. The collar calibration mandrel 4 is mainly composed of two halves 5 and 6, which are arranged to move a certain distance relative to each other in a direction perpendicular to the longitudinal axis x. For this movement, a transfer means 10 located on top of the mandrel 4 comprises arms 9a and 9b with a joint 10a. During the positioning of the mandrel 4, part of the thrust of the transfer means 10 acts on joint 10a, causing the arm parts 9a and 9b to rotate in the same direction (FIG. 3A, arrow C). This causes the two halves 5 and 6 of the mandrel 4 to move away from each other, simultaneously expanding the calibration mandrel 4 in a direction perpendicular to the longitudinal axis x. The halves 5 and 6 are formed with gripping lugs 7 and 8, which are formed with mating surfaces that are positioned against the chamfered surfaces 12 and 13 of the calibration mandrel 11 of the standard pipe 2 while the mandrel 4 is in place. The surface of the mandrel 11 is further formed with spaces 14 and 15, into which the gripping lugs 7 and 8 can fit. When the gripping lugs 7 and 8 impact the calibration mandrel 11, they are pressed against the main body of the calibration mandrel 11 with a force B. So-called wear blocks 16 and 17 can be arranged in relation to the spaces 14 and 15. Its purpose is to receive the gripping lugs 7 and 8 of the mandrel 4 which would otherwise rub against the chamfered surfaces 12 and 13 formed when the mandrels 4 and 11 move relative to each other and the halves 5 and 6 of the mandrel 4 move away from each other, generating a force F1. The wear blocks can be easily replaced if necessary.

[0014] The cross section of the mandrel 4 is dimensioned so that it can move through the opening in the collar 3 to the position shown in Figures 3A and 3B. The halves 5 and 6 of the mandrel 4 have outer surfaces that first move perpendicular to the longitudinal axis x relative to the inner surface of the collar 3, specifically from the portion where the collar diameter is smaller than the desired final size. Second, as the halves 5 and 6 move apart, these surfaces exert a force F1 on the inner surface of the collar. Under force F1, the portion of the collar 3 smaller than the desired collar diameter expands or "stretches" to the desired collar diameter size. At the same time, the internal stresses of the collar 3 change. As a result, the opposing portions of the larger-than-desired collar diameter tend to "neck" toward each other, and the surfaces of the mandrel 4 receive the collar in their corresponding positions. Finally, the mandrel 4 exerts a reaction force F1A (see Figure 3B), stopping the necking movement. The cross section of the mandrel 4 is such that the portion of the collar diameter that was originally made larger than desired maintains the desired collar diameter size, thus allowing the diameter of the collar 3 to be substantially round over its entire length.

[0015] The structure and operation of the calibration mandrel 11 for the standard pipe 2 will now be described with reference to Figures 4, 5A, 5B, and 6. The calibration mandrel 11 has a round cross section and a through hole 11a that is coaxial with its longitudinal axis x. Between its outer surface and the inner surface of the through hole 11a, the calibration mandrel 11 has first bores 19 that are parallel to the longitudinal axis y of the collar, and are arranged on both sides of the collar 3 in the direction of the longitudinal axis x of the standard pipe 2.

[0016] 6 shows an elongated pipe 25, the outer diameter of which corresponds to the inner diameter of the through-hole 11a of the calibration mandrel. Two pairs of wedge surfaces 27a, 27b are formed on the outer surface 26 of the pipe 25 and spaced apart from each other in the longitudinal direction of the pipe. The wedge surfaces of the pair of wedge surfaces 27a, 27b are located on opposite sides of the outer surface of the pipe 25. The ascending direction of each wedge surface is perpendicular to the longitudinal axis of the pipe.

[0017] A bar 29, longer than the pipe 25 in the longitudinal direction, is coaxially disposed within the pipe 25, preferably by means of a sliding joint. Two wedge surfaces 30 are formed on the surface of the bar 29 and spaced apart along the pipe's length. These wedge surfaces 30 are positioned circumferentially about the longitudinal axis between the opposing wedge surfaces 27 a, 27 b of the pipe 25 (where the wedge surfaces 27 a, 27 b are at a 90° oblique angle to the wedge surface 30) and along the longitudinal axis x near the wedge surfaces 27 a, 27 b. However, the distance between the wedge surfaces 30 is somewhat shorter than the distance between the pairs of wedge surfaces 27 a, 27 b in the longitudinal x direction. The pipe 25 is formed with openings 28 for operably connecting the wedge surfaces formed on the bar 29 with other actuators of the calibration mandrel 11.

[0018] The pipe 25 and the bar 29 are inserted into the through-holes 11a, which move relative to each other, as shown in FIG. 5A, so that the wedge surfaces 30 formed on the bar 29 connect with the first bores 19 of the mandrel 11 through the longitudinal openings 28 formed in the pipe 25. A lifting pin 22 is disposed in each of the first bores (see, in particular, FIGS. 3B and 4). The lower ends of the lifting pins 22 contact the chamfered surfaces 30 of the bars 29 located in the through-holes 11a. A flat support element 18 is disposed in association with the upper ends of the lifting pins 22, extending radially from the mandrel 11 and adjacent to its outer surface. The support element 18 is thus disposed between the outer circumferential surface of the calibration mandrel 11 and the inner circumferential surface of the standard pipe 2. The running surface of the calibration mandrel 11 has recesses for the support elements 18.

[0019] Similarly, wedge surfaces 27a, 27b formed on pipe 25 connect at corresponding locations with second bores 21 of mandrel 11. A lifting pin 13 is also disposed in each second bore 21. The lower end of each lifting pin 13 contacts at corresponding locations with wedge surfaces 27a, 27b of pipe 25. A flat support element 20 is disposed in association with the upper end of each lifting pin 13, the upper end extending in the radial direction of mandrel 11 close to the outer surface of mandrel 11.

[0020] According to the disclosed embodiment, the calibration mandrel 11 extends in the axial direction y of the collar 3 as follows: When the bar 29 is moved in the longitudinal direction x, the lifting pin 22 moves perpendicular to the longitudinal axis (y direction) due to the action of the wedge surface 30, lifting the flat support element against the inner surface of the standard pipe 2, as shown in FIG. 4 . A separate power unit (not shown here) can be used to move the bar 29. The support element 18 exerts a force F2 against the inner surface of the standard pipe 2 adjacent to the collar 3, which corrects the deformation of the standard pipe 2 adjacent to the collar 3. The calibration mandrel 4 of the collar 3 is pressed against the support element 24 by the calibration mandrel 11 of the standard pipe 2, so that the T-branch pipe 1 is held in place. Furthermore, the plunger 31 acts on the standard pipe 2 from the outside by a force F4, which forms a counter-support for force F2, as will be described later with reference to FIG. 7 .

[0021] After this, the calibration mandrel 11 is stretched transversely to the direction of the longitudinal axis x of the standard pipe 2 by moving the pipe 25 around the bar 29 using a separate power unit (not shown) in a manner corresponding to the movement of the bar 29 in the direction of the longitudinal axis x. Next, the lifting pin 23 moves transversely with respect to the y axis (and therefore also with respect to the longitudinal axis x) due to the effect of the rising of the wedge surfaces 27a and 27b (FIG. 6), causing the flat support element 20 to move against the inner surface of the standard pipe 2, as shown in FIGS. 5A and especially 5B. The support element 20 exerts a force F3 against the inner peripheral surface of the standard pipe 2, which acts in the circumferential direction of the standard pipe 2 on both sides of force F2 at an angle opposite to force F2 by 90 degrees. Force F3 corrects the deformation formed in the standard pipe 2 in the circumferential direction of the standard pipe 2, which is substantially transverse to the deformation corrected by force F2. In the X-axis direction, force F2 is closer to the collar than force F3, which is closer to the end of standard pipe 2. This is achieved by positioning pins 22 and 23 so that pin 22 lifts the inner end of support element 18 and pin 23 lifts the outer end of support element 20. In this way, the calibrated forces can be applied at the correct points.

[0022] 7 further shows plungers 31 positioned relative to both ends of the standard pipe 2, which apply a force F4 substantially parallel to the y-axis to both ends of the standard pipe 2. Under force F4, the standard pipe 2 is reduced in size from both ends to its original size, and the cross section of the pipe 2 becomes substantially round.

[0023] Support element 18 and force F2 form the support point for force F4, which is generated by plunger 31. Plunger 31 is designed to be positioned over a portion of the circumference of standard pipe 2 and to force the pipe into the correct shape when force F4 is applied. Thus, forces F1, F1a, F2, F3, and F4 act simultaneously on T-branch pipe 1. Each force affects the material of T-branch pipe 1 so that, when the force is removed, the T-branch pipe maintains the shape "forced" by the force. In other words, at the critical point at which the force acts on T-branch pipe 1, the force exceeds the yield point of the material. Elastic recovery of the material also occurs, which must be taken into account when determining the dimensions of the calibration element.

[0024] The method according to the invention and the device for implementing it are not limited to the disclosed embodiments only, but the invention can be applied in several ways within the scope of protection defined in the appended claims.

Claims

1. A method for calibrating the dimensions of a T-branch pipe (1), comprising: T-branch pipes are Standard pipe (2), a collar (3) forming a branching port, The diameter of the collar is larger than the desired final dimension in the longitudinal direction (x) of the standard pipe (2) and smaller than the desired final dimension in the transverse direction; The method involves flaring out in stages, such that the collar (3) is flared out by a first calibrated force (F1) in one direction, which is transverse to the longitudinal direction (x) of the standard pipe (2), and the standard pipe (2) is locally flared out in two directions by a second calibrated force (F2) and a third calibrated force (F3), until all three calibrated forces (F1, F2, and F3) act simultaneously.

2. When the calibration forces (F1, F2, and F3) are applied, the standard pipe (2) is compressed near its ends by a force (F4) acting parallel to the axial direction (y) of the collar (3); The method of claim 1.

3. The calibration mandrel (11) of the standard pipe (2) is inserted into the standard pipe (2), The calibration mandrel (4) of the collar (3) is lowered through the collar (3) onto the calibration mandrel (11) of the standard pipe (2); the calibration mandrel (4) of the collar (3) extends transversely to the longitudinal direction (x) of the standard pipe (2) and flares out the collar (3) in the corresponding direction; The calibration mandrel (11) of the standard pipe (2) extends in the axial direction (y) of the collar (3) and flares out the standard pipe (2) next to the collar (3) in the corresponding direction; The calibration mandrel (11) of the standard pipe (2) extends transversely to the axial direction (y) of the collar (3) and flares out the standard pipe (2) in the corresponding direction; The method according to claim 1 or 2.

4. A device for calibrating the dimensions of a T-branch pipe (1), comprising: T-branch pipes are Standard pipe (2), a collar (3) forming a branching port, The diameter of the collar is larger than the desired final dimension in the longitudinal direction (x) of the standard pipe (2) and smaller than the desired final dimension in the transverse direction; The device is a collar (3) calibration mandrel (4) including first calibration members (5, 6) by means of which a first calibration force (F1) can be applied to the collar (3) transversely to the longitudinal direction (x) of the standard pipe (2) to flare out the collar in a corresponding direction; a standard pipe (2) calibration mandrel (11) including a second calibration member (18) by which a second calibration force (F2) can be applied to the standard pipe (2) adjacent to the collar (3) in the axial direction (y) of the collar (3) to flare out the standard pipe; a third calibration member (20) by means of which a third calibration force (F3) can be exerted on the standard pipe (2) in a direction transverse to the axial direction (y) of the collar (3) in order to flare out the standard pipe (2); An apparatus that stages the aforementioned flare-out so that ultimately all three calibrated forces (F1, F2, F3) are acting simultaneously.

5. It includes plungers (31) fitted relative to both ends of the standard pipe (2), When the calibrated forces (F1, F2, F3) act simultaneously, this plunger allows the standard pipe (2) to be contracted near both ends under a force (F4) acting parallel to the axial direction (y) of the collar (3).

5. The apparatus of claim 4.

6. The calibration mandrel (11) of the standard pipe (2) is insertable into the standard pipe (2), and the calibration mandrel (4) of the collar (3) is movable through the collar (3) relative to the calibration mandrel (11) of the standard pipe (2); 6. The device according to claim 4 or 5.

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