Pipe fitting internal high-pressure forming control system and control method

Abstract

The invention discloses a pipe fitting internal high-pressure forming control system and method, and relates to the technical field of pipe forming. The pipe fitting internal high-pressure forming control system comprises a first sensor, a second sensor, a third sensor and a controller; the first sensor, the second sensor and the third sensor are embedded in the side wall of the branch pipe cavity and / or the branch pipe punch; the first sensor, the second sensor and the third sensor are respectively used for measuring distances to the surface of a bulging area of the pipe; the controller is connected with the first sensor, the second sensor and the third sensor. The control method comprises the steps that when the pipe is in a free bulging stage, the first sensor, the second sensor and the third sensor are used for measuring the distances to the surface of a bulging area of the pipe correspondingly; determining relative positions of three measuring points on the surface of the bulging area; and determining the bulging curvature of the bulging area. According to the invention, the curvature change in the pipe bulging process can be detected, so that the technological parameters can be adjusted, and the bulging processes of different pipes are kept consistent.

Description

Technical Field

[0001] The present invention relates to the technical field of pipe forming, and particularly to a control system and a control method for internal high-pressure forming of pipe fittings. Background Art

[0002] Pipe fittings such as tee pipes, as important flow channel components, are widely used in fields such as aerospace and automotive manufacturing. At present, tee pipes are mainly formed by internal high-pressure technology. Compared with the processes of socket welding or stamping and welding, internal high-pressure forming has advantages such as no weld seams, high reliability, smooth inner surface, and small fluid resistance.

[0003] At present, during the internal high-pressure forming process of tee pipes, there are still some problems to be solved. Specifically, when the pipe starts to bulge and is in the free bulging stage, due to the manufacturing process and metallurgical process errors of the pipes, there are fluctuations in the yield strength between the pipes, resulting in different bulging curvatures of different pipes under the same feeding conditions, which poses a hidden danger for subsequent forming.

[0004] In view of the above problems in the prior art, those skilled in the art urgently need a control system and a control method for internal high-pressure forming of pipe fittings. Summary of the Invention

[0005] The purpose of the present invention is to provide a control system and a control method for internal high-pressure forming of pipe fittings to solve the problems existing in the above prior art, and to be able to detect the change in curvature during the bulging process of the pipe and then adjust the process parameters to make the bulging processes of different pipes consistent.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] In a first aspect, the present invention provides a control system for internal high-pressure forming of pipe fittings, including a first sensor, a second sensor, a third sensor, and a controller; the first sensor, the second sensor, and the third sensor are embedded inside the side wall of the branch pipe cavity and / or inside the branch pipe punch; the first sensor, the second sensor, and the third sensor are respectively used to measure the distance to the surface of the bulging area of the pipe, and the three measurement points corresponding to the first sensor, the second sensor, and the third sensor on the surface of the bulging area are not on the same straight line; the controller is connected to the first sensor, the second sensor, and the third sensor, and is used to determine the bulging curvature of the bulging area according to the measurement values of the first sensor, the second sensor, and the third sensor.

[0008] In some embodiments, the first sensor is embedded inside the branch punch, and the detection direction of the first sensor is along the axis direction of the branch cavity; the second sensor and the third sensor are both embedded inside the side wall of one end of the branch cavity close to the main cavity, and the connection line of the detection directions of the second sensor and the third sensor is vertically intersected with the axis of the branch cavity.

[0009] In some embodiments, a fourth sensor is further included. A plurality of the fourth sensors are embedded inside the side wall of the branch cavity along the direction parallel to the axis of the branch cavity. The plurality of the fourth sensors are respectively used for measuring the distances to the surface of the fillet at the top of the branch; the detection directions of the plurality of the fourth sensors are parallel and all vertically intersected with the axis of the branch cavity, or the detection directions of the plurality of the fourth sensors are parallel and all inclined from the transmitting end towards the direction close to the main cavity along the direction of the axis of the branch cavity; the controller is connected to the plurality of the fourth sensors and is used for determining the fillet size at the top of the branch according to the measured values of the plurality of the fourth sensors.

[0010] In some embodiments, two assembly grooves are provided inside the side wall of the branch cavity. A plurality of the fourth sensors arranged along the direction parallel to the axis of the branch cavity are provided in both of the two assembly grooves, and the plurality of the fourth sensors in the two assembly grooves are staggered along the direction parallel to the axis of the branch cavity; and / or the plurality of the fourth sensors are arranged at equal intervals along the direction parallel to the axis of the branch cavity.

[0011] In a second aspect, the present invention further provides a control method for internal high-pressure forming of a pipe fitting. By using the above internal high-pressure forming control system for a pipe fitting, the method includes the following steps: when the pipe is in the free bulging stage, the first sensor, the second sensor, and the third sensor embedded inside the side wall of the branch cavity and / or inside the branch punch are respectively used for measuring the distances to the surface of the bulging area of the pipe; the relative positions of three measurement points on the surface of the bulging area are determined according to the relative positions and the measured values of the first sensor, the second sensor, and the third sensor; the bulging curvature of the bulging area is determined according to the relative positions of the three measurement points; wherein, the three measurement points on the surface of the bulging area corresponding to the first sensor, the second sensor, and the third sensor are not on the same straight line.

[0012] In some embodiments, a plurality of fourth sensors are embedded inside the side wall of the branch pipe cavity along a direction parallel to the axis of the branch pipe cavity. The method further includes: when the pipe is in the branch pipe forming stage, using the plurality of fourth sensors to respectively measure the distances to the surface of the fillet at the top of the branch pipe; determining, according to the measurement values of the plurality of fourth sensors, a plurality of distance values along the detection direction of the fourth sensors between the inner wall surface of the branch pipe cavity and the surface of the fillet at the top of the branch pipe; determining the size of the fillet at the top of the branch pipe according to the plurality of distance values and the spacing between the corresponding plurality of fourth sensors; when the pipe is in the shaping stage, determining the back pressure distance of the branch pipe punch according to the size of the fillet at the top of the branch pipe; applying a supporting internal pressure inside the pipe, and moving the back pressure distance in a direction towards the main pipe cavity by using the branch pipe punch.

[0013] In some embodiments, the method further includes: after the step of determining the bulging curvature of the bulging area according to the relative positions of three measurement points, the method further includes: comparing the bulging curvature with a preset curvature value; if the bulging curvature is greater than the preset curvature value, reducing the forming internal pressure of the pipe; if the bulging curvature is less than the preset curvature value, increasing the forming internal pressure of the pipe.

[0014] In some embodiments, after the step of determining the size of the fillet at the top of the branch pipe according to the plurality of distance values and the spacing between the corresponding plurality of fourth sensors, the method further includes: comparing the size of the fillet at the top of the branch pipe with a preset interval; if the size of the fillet at the top of the branch pipe is less than the minimum value of the preset interval, increasing the retraction speed of the branch pipe punch and / or reducing the feeding amount of the main pipe punch; if the size of the fillet at the top of the branch pipe is greater than the maximum value of the preset interval, reducing the retraction speed of the branch pipe punch and / or increasing the feeding amount of the main pipe punch.

[0015] In some embodiments, the detection directions of the plurality of fourth sensors are parallel and all perpendicularly intersect with the axis of the branch pipe cavity, and the plurality of fourth sensors are arranged at equal intervals along a direction parallel to the axis of the branch pipe cavity; determining the radius r1 of the fillet at the top of the branch pipe according to the plurality of distance values and the spacing d1 between the corresponding plurality of fourth sensors, and the calculation formula is as follows:

[0016]

[0017] where n is the number of the fourth sensors for measuring the fillet at the top of the branch pipe; i = 1, 2,..., n; X n is the nth distance value.

[0018] Or the detection directions of the plurality of fourth sensors are parallel and are all inclined at an angle of 45° from the transmitting end to the direction of the axis of the branch pipe cavity toward the direction close to the main pipe cavity, and the plurality of fourth sensors are arranged at equal intervals along the direction parallel to the axis of the branch pipe cavity; the radius r2 of the fillet at the top of the branch pipe is calculated according to the plurality of distance values ​​and the corresponding intervals d2 between the plurality of fourth sensors, and the calculation formula is as follows:

[0019]

[0020] Wherein, m is the number of the fourth sensors measuring the fillet of the top of the branch pipe; j=1, 2, ..., m; X m is the mth distance value.

[0021] In some embodiments, the back pressure distance h of the branch pipe punch is determined according to the fillet size r of the branch pipe top, and the calculation formula is as follows:

[0022]

[0023] Wherein, R1 is the radius of the contact surface between the top of the branch pipe and the branch pipe punch, R is half of the outer diameter of the branch pipe, and t is the average wall thickness of the branch pipe.

[0024] Compared with the prior art, the present invention has achieved the following technical effects:

[0025] In the control system and control method for high pressure forming inside a pipe fitting of the present invention, when the branch pipe area of ​​the pipe begins to bulge but does not contact the branch pipe punch, it is in a free bulging stage, and the first sensor, the second sensor and the third sensor are used to respectively measure the distance to the surface of the bulging area of ​​the pipe, wherein the first sensor, the second sensor and the third sensor can be all embedded in the side wall of the branch pipe cavity or all embedded in the branch pipe punch or respectively embedded in the side wall of the branch pipe cavity and the branch pipe punch, as long as the distance to three non-collinear measurement points on the surface of the bulging area can be measured; the controller can obtain the relative position between the corresponding three measurement points according to the relative positions and measurement values ​​of the three sensors, and then the curvature of the curve where the three measurement points are located, that is, the curvature of the bulging area, can be calculated according to the relative positions between the three measurement points, so that the present invention can detect the change of curvature during the bulging process of the pipe, and specifically adjust the process parameters so that the bulging process of different pipes remains consistent, that is, under the same amount of feed, the same bulging curvature is obtained to ensure the consistency of the forming of pipe fittings such as tees.

[0026] Furthermore, in the present invention, the first sensor is embedded inside the branch pipe punch, and the distance to the top of the bulging area is measured by the first sensor; the second sensor and the third sensor are embedded inside the side wall of one end of the branch pipe cavity close to the main pipe cavity, and the connecting line of the detection directions of the second sensor and the third sensor is perpendicular to and intersects with the axis of the branch pipe cavity, and the distances to two measurement points symmetric about the axis of the branch pipe cavity on the lower surface of the bulging area are measured by the second sensor and the third sensor; thus, the three measurement points corresponding to the three sensors of the present invention are far apart from each other, so as to more easily measure the curvature change of the bulging area and perform regulation and control, improving the accuracy of the detection result.

[0027] Furthermore, after the branch pipe area of the pipe in the present invention contacts the branch pipe punch and enters the branch pipe forming stage, in this stage, a plurality of fourth sensors are used to detect the fillet area at the top of the branch pipe, and the size of the fillet at the top of the branch pipe is calculated. Thus, the present invention can specifically adjust the process parameters according to the size of the fillet at the top of the branch pipe, and can avoid the adverse effects on the forming quality of the branch pipe caused by the inability to directly observe the forming condition of the branch pipe in the die cavity.

[0028] Furthermore, two assembly grooves are provided on the side wall of the branch pipe cavity, a plurality of fourth sensors are arranged in both of the two assembly grooves, and the plurality of fourth sensors in the two assembly grooves are arranged staggeredly, so as to increase the number of fourth sensors for detecting the fillet area at the top of the branch pipe, making the calculation result of the size of the fillet at the top of the branch pipe more accurate. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0030] Figure 1 It is a cross-sectional view of the internal high-pressure forming control system of the pipe fitting in some embodiments of the present invention when the pipe is in the initial stage;

[0031] Figure 2 It is a cross-sectional view of the internal high-pressure forming control system of the pipe fitting in some embodiments of the present invention when the pipe is in the free bulging stage;

[0032] Figure 3 It is a cross-sectional view of the internal high-pressure forming control system of the pipe fitting in some embodiments of the present invention when the pipe is in the forming stage;

[0033] Figure 4A It is one of the schematic diagrams for measuring the size of the fillet at the top of the branch pipe in the first embodiment of the present invention;

[0034] Figure 4B The second schematic diagram for measuring the fillet size at the top of the branch pipe in the first embodiment of the present invention;

[0035] Figure 4C The third schematic diagram for measuring the fillet size at the top of the branch pipe in the first embodiment of the present invention;

[0036] Figure 5A The first schematic diagram for measuring the fillet size at the top of the branch pipe in the second embodiment of the present invention;

[0037] Figure 5B The second schematic diagram for measuring the fillet size at the top of the branch pipe in the second embodiment of the present invention;

[0038] Figure 5C The third schematic diagram for measuring the fillet size at the top of the branch pipe in the second embodiment of the present invention;

[0039] Figure 6A The schematic diagram of the branch pipe of the pipe material before shaping in some embodiments of the present invention;

[0040] Figure 6B The schematic diagram of the branch pipe of the pipe material after shaping in some embodiments of the present invention;

[0041] Figure 7 The first step flow chart of the internal high-pressure forming control method for pipe fittings in some embodiments of the present invention;

[0042] Figure 8 The second step flow chart of the internal high-pressure forming control method for pipe fittings in some embodiments of the present invention.

[0043] In the figure: 1 - forming die; 2 - first main pipe punch; 3 - second main pipe punch; 4 - branch pipe punch; 5 - branch pipe cavity; 6 - main pipe cavity; 7 - first sensor; 8 - second sensor; 9 - third sensor; 10 - assembly groove; 11 - pipe material; 12 - controller. Specific embodiments

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] The purpose of the present invention is to provide an internal high-pressure forming control system and control method for pipe fittings to solve the problems existing in the prior art, and be able to detect the change in curvature during the bulging process of the pipe material and then adjust the process parameters to make the bulging processes of different pipe materials consistent.

[0046] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0047] The present invention provides an internal high-pressure forming control system for pipe fittings, as Figure 1 shown in FIGS. 1 to 6, including a first sensor 7, a second sensor 8, a third sensor 9, and a controller 12. Figure 1 Among them, the upper die and the lower die are correspondingly buckled to form a forming die 1. The inside of the forming die 1 has a main pipe cavity 6 and a branch pipe cavity 5 that are connected. The pipe 11 is placed in the main pipe cavity 6. The first main pipe punch 2 and the second main pipe punch 3 are used to seal both ends of the pipe 11. The branch pipe punch 4 is arranged in the branch pipe cavity 5. A liquid injection hole communicating with the main pipe cavity 6 is arranged inside the first main pipe punch 2 or the second main pipe punch 3 for injecting high-pressure liquid into the main pipe cavity 6 so that the inside of the pipe 11 has a forming internal pressure. The first sensor 7, the second sensor 8, and the third sensor 9 of the present invention can all be embedded inside the side wall of the branch pipe cavity 5, or can all be embedded inside the branch pipe punch 4, or can be respectively embedded inside the side wall of the branch pipe cavity 5 and inside the branch pipe punch 4; and the three measurement points on the surface of the bulging area corresponding to the first sensor 7, the second sensor 8, and the third sensor 9 are not on the same straight line.

[0048] When the branch of the pipe 11 starts to bulge but does not contact the branch pipe punch 4, it is in the free bulging stage. The first sensor 7, the second sensor 8, and the third sensor 9 respectively measure the distances of three non-collinear measurement points on the surface of the bulging area of the pipe 11. The controller 12 is connected to the first sensor 7, the second sensor 8, and the third sensor 9 for receiving the measurement data, and can calculate the relative positions of the three measurement points according to the relative positions and measurement values between the first sensor 7, the second sensor 8, and the third sensor 9, and then calculate the curvature of the curve corresponding to these three measurement points, that is, the curvature of the bulging area here, and adjust the process parameters accordingly.

[0049] Therefore, the present invention can effectively eliminate the influence brought by the material property fluctuations between different pipes, ensure that the bulging process of each pipe can be kept consistent, thereby preventing possible adverse effects on subsequent forming, improving the stability and reliability of the forming process, that is, under the same amount of supplementary material, the same bulging curvature can be obtained, and the consistency of the forming of pipe fittings such as three-way pipes can be guaranteed.

[0050] In some embodiments, the first sensor 7 is embedded inside the branch punch 4, and both the second sensor 8 and the second sensor 9 are embedded inside the side wall of the branch cavity 5 on the side close to the main cavity 6. Specifically, the second sensor 8 and the second sensor 9 can be embedded inside the side wall at the junction of the branch cavity 5 and the main cavity 6, that is, at the rounded corner of the transition zone of the forming die 1. It should be noted that in the present invention, a first groove can be provided inside the branch punch 4, and the first sensor 7 can be correspondingly embedded in the first groove, and the first groove communicates with the branch cavity 5; in the present invention, a second groove and a third groove can be provided on the side wall of the branch cavity 5 close to the main cavity 6, the second sensor 8 can be correspondingly embedded in the second groove, the third sensor 9 can be correspondingly embedded in the third groove, and both the second groove and the third groove communicate with the branch cavity 5.

[0051] In some embodiments, the first sensor 7 is embedded in the central position of the cross-section of the branch punch 4 along the axis direction of the branch cavity 5, that is, the first sensor 7 detects along the axis direction of the branch cavity 5 and is used to detect the distance to the center of the top surface of the branch bulging area of the pipe 11; the connecting line of the detection directions of the second sensor 8 and the third sensor 9 is perpendicular to and intersects the axis of the branch cavity 5, and the second sensor 8 and the third sensor 9 are used to measure the distances to two measurement points symmetric about the axis of the branch cavity 5 on the lower surface of the branch bulging area of the pipe 11; thus, the three measurement points corresponding to the first sensor 7, the second sensor 8 and the third sensor 9 of the present invention are far apart, which is convenient for detecting the curvature change of the bulging area and performing regulation and control, and improving the accuracy of the detection result.

[0052] It should be noted that in the embodiments of the present invention, the example where the connecting line of the detection directions of the second sensor 8 and the third sensor 9 is perpendicular to and intersects the axis of the branch cavity 5 is taken for illustration. Those skilled in the art can also configure the connecting line of the detection directions of the second sensor 8 and the third sensor 9 to intersect but not be perpendicular to the axis of the branch cavity 5.

[0053] In some embodiments, the control system of the present invention further includes a fourth sensor. A plurality of fourth sensors are embedded inside the side wall of the branch cavity 5 along a direction parallel to the axis of the branch cavity 5; the detection directions of the plurality of fourth sensors are parallel and perpendicular to and intersect with the axis of the branch cavity 5; or the detection directions of the plurality of fourth sensors are parallel and all inclined at a certain angle towards the direction close to the main cavity 6, that is, the detection directions of the plurality of fourth sensors are inclined from the emitting end towards the direction close to the main cavity 6 at one end close to the axis of the branch cavity 5. When the branch of the pipe 11 starts to contact the branch punch 4 and is in the branch forming stage, the distances from the plurality of fourth sensors to the rounded surface at the top of the branch are measured correspondingly, and a plurality of distance values along the detection direction of the fourth sensors between the inner wall surface of the branch cavity 5 and the rounded surface at the top of the branch are calculated. The controller 12 is connected to the plurality of fourth sensors and is used to calculate the size of the rounded corner at the top of the branch according to the plurality of distance values and the distances between the corresponding plurality of fourth sensors, and specifically adjust the process parameters according to the size of the rounded corner at the top of the branch.

[0054] In some embodiments, two assembly grooves 10 are arranged circumferentially inside the side wall of the branch cavity 5 of the present invention. A plurality of fourth sensors arranged along a direction parallel to the axis of the branch cavity 5 are arranged inside both of the two assembly grooves 10. A detection channel communicating with each other is arranged between the two assembly grooves 10 and the branch cavity 5, and the plurality of fourth sensors perform detections through the corresponding detection channels. Moreover, the plurality of fourth sensors in the two assembly grooves 10 of the present invention are staggered along the direction parallel to the axis of the branch cavity 5, which can increase the number of fourth sensors irradiating the rounded corner area at the top of the branch, that is, the plurality of fourth sensors for measuring the rounded corner area at the top of the branch are arranged more densely, making the detection result more accurate.

[0055] It should be noted that the embodiments of the present invention are described by taking the setting of two assembly grooves as an example. Those skilled in the art can also set the number of assembly grooves to be greater than two, and the present invention does not make specific limitations.

[0056] In some embodiments, the plurality of fourth sensors are arranged at equal intervals along a direction parallel to the axis of the branch cavity 5.

[0057] It should be noted that the first sensor 7, the second sensor 8, the third sensor 9, and the fourth sensor of the present invention can all be laser sensors. Those skilled in the art can also select other types of sensors for measurement according to the actual situation. The present invention does not make specific limitations as long as the corresponding measurement effects can be achieved. Moreover, the second sensor 8 and the third sensor 9 of the present invention can be symmetrically arranged or asymmetrically arranged with respect to the axis of the branch cavity 5, and the two assembly grooves 10 can be symmetrically arranged or asymmetrically arranged with respect to the axis of the branch cavity 5, and the present invention does not make specific limitations.

[0058] The present invention also provides a control method for internal high-pressure forming of pipe fittings, as Figures 1 to 8 shown, which includes the following steps:

[0059] Step S1: When the pipe 11 is in the free bulging stage, the first sensor 7, the second sensor 8, and the third sensor 9 embedded inside the side wall of the branch cavity 5 and / or inside the branch punch 4 are used to measure the distances to the surface of the bulging area of the pipe 11 respectively;

[0060] Step S2: Determine the relative positions of three measurement points on the surface of the bulging area according to the relative positions and measurement values of the first sensor 7, the second sensor 8, and the third sensor 9;

[0061] Step S3: Determine the bulging curvature of the bulging area according to the relative positions of the three measurement points;

[0062] Step S4: Regulate the process parameters according to the bulging curvature.

[0063] Based on the above steps S1 to S4, it should be noted that after closing the upper die and the lower die, the two ends of the pipe 11 are sealed by the first main punch 2 and the second main punch 3. At this time, the internal pressure of the pipe 11 is controlled to continuously increase, and the first main punch 2 and the second main punch 3 start to move in the direction towards the pipe 11 for feeding. The branch area of the pipe 11 starts to freely bulge along the branch cavity 5. At this time, the branch bulging area of the pipe 11 is not in contact with the branch punch 4 and is in the free bulging stage. And the present invention calculates the relative positions of three non-collinear measurement points by subtracting the corresponding measurement values from the relative positions of the first sensor 7, the second sensor 8, and the third sensor 9; then calculates the bulging curvature by the three-point method according to the relative positions of the three measurement points.

[0064] Specifically, assume that the three measurement points are A, B, and C. The three measurement points are connected to form a triangle △ABC. The lengths of the three sides of the triangle △ABC are a, b, and c. The curvature of the curve corresponding to the three measurement points can be regarded as the curvature of the circumcircle of the triangle △ABC. Assume that the center of the circumcircle is O. Then the calculation formula for the radius r0 of the circumcircle is as follows:

[0065]

[0066] cos∠BOC = 2cos 2 ∠BAC - 1

[0067]

[0068] According to the above formula, the radius r0 of the circumscribed circle can be calculated. The curvature of the circumscribed circle is the reciprocal of its radius r0. Therefore, according to the relative positions of the three measurement points and through the three-point method, the present invention can calculate the corresponding bulging curvature, and then can adjust the process parameters according to the bulging curvature.

[0069] In some embodiments, the above step S4 includes:

[0070] Step S41: Compare the bulging curvature with a preset curvature value;

[0071] Step S42: If the bulging curvature is less than the preset curvature value, increase the forming internal pressure of the pipe 11;

[0072] Step S43: If the bulging curvature is greater than the preset curvature value, decrease the forming internal pressure of the pipe 11.

[0073] The present invention executes the above steps S41 to S43 through the controller 12, and adjusts the forming internal pressure of the pipe 11 according to the comparison result between the measured bulging curvature value and the preset curvature value. The preset curvature value can be the detected value of the bulging curvature of the previous pipe. Therefore, the present invention can control the forming process in real time, ensure that under the same feeding amount, the same bulging curvature is obtained, and guarantee the consistency of the forming of the tee pipe.

[0074] In some embodiments, after the above step S4, the control method of the present invention further includes:

[0075] Step S5: When the pipe 11 is in the branch forming stage, use a plurality of fourth sensors to respectively measure the distances to the surface of the fillet at the top of the branch;

[0076] Step S6: Determine a plurality of distance values along the detection direction of the fourth sensors between the inner wall surface of the branch cavity 5 and the surface of the fillet at the top of the branch according to the measurement values of the plurality of fourth sensors;

[0077] Step S7: Determine the size of the fillet at the top of the branch according to the plurality of distance values and the spacing between the corresponding plurality of fourth sensors;

[0078] Step S8: Adjust the process parameters according to the size of the fillet at the top of the branch.

[0079] Based on the above steps S5 to S8, it should be noted that during the branch pipe forming stage, as the first main pipe punch 2 and the second main pipe punch 3 continuously supply materials, the top end of the branch pipe begins to contact the branch pipe punch 4, and the branch pipe punch 4 starts to retreat, and the height of the branch pipe continuously increases. Multiple fourth sensors respectively measure the distance to the branch pipe punch 4, the distance to the rounded corner surface at the top of the branch pipe, and the distance to the straight wall area of the branch pipe. Since the detection directions of the multiple fourth sensors are parallel to each other, the number of fourth sensors measuring the rounded corner surface at the top of the branch pipe can be obtained according to the different measurement values of the multiple fourth sensors; and by subtracting the measured distance to the straight wall area of the branch pipe from the measured distance to the rounded corner area at the top of the branch pipe, multiple distance values between the inner wall surface of the branch pipe cavity 5 and the rounded corner surface at the top of the branch pipe in the detection direction of the fourth sensor can be obtained.

[0080] In some embodiments, the above step S8 includes:

[0081] Step S81: Compare the size of the rounded corner at the top of the branch pipe with a preset range;

[0082] Step S82: If the size of the rounded corner at the top of the branch pipe is less than the minimum value of the preset range, increase the retreat speed of the branch pipe punch 4 and / or reduce the material supply amount of the main pipe punch;

[0083] Step S83: If the size of the rounded corner at the top of the branch pipe is greater than the maximum value of the preset range, reduce the retreat speed of the branch pipe punch 4 and / or increase the material supply amount of the main pipe punch.

[0084] It should be noted that the material supply amount of the main pipe punch here is the material supply amounts of the first main pipe punch 2 and the second main pipe punch 3. The controller 12 executes the above steps S81 to S83 to keep the size of the rounded corner at the top of the branch pipe within a small range, avoiding defects, especially avoiding cracking of the rounded corner at the top of the branch pipe.

[0085] During the branch pipe forming stage, since relevant personnel cannot clearly observe the branch pipe forming situation and the contact situation with the branch pipe punch 4, once the contact area between the top end of the branch pipe and the branch pipe punch 4 is too large or too small, it will cause uneven wall thickness distribution of the product, and even defects such as wrinkling or cracking may occur. The present invention can greatly reduce the potential impact on the forming quality of the branch pipe caused by the inability to directly observe the branch pipe forming condition in the mold cavity; by measuring the rounded corner size and precisely controlling key parameters such as the material supply amount and the retreat amount of the branch pipe punch 4 according to the rounded corner size, the possibility of defects caused by the mismatch of these parameters is significantly reduced, making the entire branch pipe forming process more controllable, thereby greatly improving the qualified rate of product forming.

[0086] In some embodiments, such as Figure 4A 、 Figure 4B 、 Figure 4CAs shown, the present invention provides a method for measuring the fillet size at the top of the branch pipe. The detection directions of multiple fourth sensors are parallel and all perpendicularly intersect with the axis of the branch pipe cavity 5. The multiple fourth sensors are arranged at equal intervals along the direction parallel to the axis of the branch pipe cavity 5. As shown in Figure 4a, X1 to X n are multiple distance values between the inner wall surface of the branch pipe cavity 5 and the fillet surface at the top of the branch pipe, and the distance between two adjacent fourth sensors corresponding to two adjacent distance values in X1 to X n is equal and is d1; the area S1 of the region enclosed by the fillet surface at the top of the branch pipe, the inner wall surface of the branch pipe cavity 5, and the end face of the branch pipe punch 4 can be approximately regarded as the sum S2 of multiple rectangular areas. The calculation formula of S2 is as follows:

[0087]

[0088] The area S1 is the area of a square minus the area of a quarter circle, and its calculation formula is as follows:

[0089]

[0090] where r1 is the radius of the fillet at the top of the branch pipe, n is the number of fourth sensors used to measure the fillet at the top of the branch pipe; i = 1, 2,..., n; X n is the nth distance value.

[0091] When d1 approaches 0 infinitely, the area S2 can be approximately equal to the area S1. Then the calculation formula of the fillet radius r1 at the top of the branch pipe is as follows:

[0092]

[0093] It can be understood that when calculating the fillet radius at the top of the branch pipe by the above method, the more the number of fourth sensors for detecting the fillet at the top of the branch pipe, the smaller the error of the calculated fillet radius.

[0094] In some embodiments, as Figure 5A , Figure 5B , Figure 5C shown, the present invention provides another method for measuring the fillet size at the top of the branch pipe. The detection directions of multiple fourth sensors are parallel and all inclined at an angle of 45° towards the direction close to the main pipe cavity 5. The multiple fourth sensors are arranged at equal intervals along the direction parallel to the axis of the branch pipe cavity 5. Due to the presence of the branch pipe punch 4, only half of the fillet area at the top of the branch pipe will be irradiated, and the corresponding multiple fourth sensors detect this half fillet area more densely, that is, the number of fourth sensors for detecting this half fillet area increases. As shown in Figure 4a, X1 to X m are multiple distance values between the inner wall surface of the branch pipe cavity 5 and the fillet surface at the top of the branch pipe, and X1 to X mThe distance between two adjacent fourth sensors corresponding to the two distance values is equal and is d2; half of the area S1 of the region enclosed by the surface of the rounded corner area at the top of the branch pipe, the inner wall surface of the branch pipe cavity 5, and the end face of the branch pipe punch 4 can be approximately regarded as the sum S3 of the areas of multiple rectangles, and the calculation formula is as follows:

[0095]

[0096] where r2 is the radius of the rounded corner at the top of the branch pipe, and m is the number of fourth sensors used to measure the rounded corner at the top of the branch pipe; j = 1, 2,..., m; X m is the m-th distance value.

[0097] When d2 approaches 0 infinitely, the area S3 can be approximately equal to half of the area S1, and the calculation formula for the radius r2 of the rounded corner at the top of the branch pipe is as follows:

[0098]

[0099] Similarly, when calculating the radius of the rounded corner at the top of the branch pipe using the above method, the more the number of fourth sensors for detecting the rounded corner area at the top of the branch pipe, the smaller the error of the calculated rounded corner radius.

[0100] In some embodiments, after the above step S8, the control method of the present invention further includes:

[0101] Step S9: When the pipe 11 is in the shaping stage, determine the back pressure distance of the branch pipe punch 4 according to the size of the rounded corner at the top of the branch pipe;

[0102] Step S10: Apply a supporting internal pressure inside the pipe 11, and move the branch pipe punch 4 back a distance along the direction towards the main pipe cavity 6.

[0103] Based on the above steps S9 and S10, it should be noted that after the forming of the branch pipe is completed, at this time, the rounded corner at the top of the branch pipe is relatively large and the effective height is relatively small. It is necessary to shape the rounded corner area at the top of the branch pipe. The existing forming process requires all punches to stop moving, and then quickly increase the internal pressure to make the rounded corner at the top of the branch pipe meet the design requirements. This is likely to cause cracking in the rounded corner area and requires high requirements for equipment and molds. In the above step S9 of the present invention, the controller 12 calculates the back pressure distance of the branch pipe punch 4 according to the size of the rounded corner at the top of the formed branch pipe based on the principle of constant plastic deformation volume; when the present invention performs shaping, the first main pipe punch 2 and the second main pipe punch 3 remain stationary, and it is ensured that there is a certain supporting internal pressure inside the pipe 11, and this supporting internal pressure is less than the forming internal pressure, and the rounded corner area at the top of the branch pipe is shaped by the back pressure of the branch pipe punch 4, and the finished product is taken out after the shaping is completed.

[0104] Such as Figure 6A and Figure 6BThe figure shows the dimensional schematic diagrams of the rounding area at the top of the branch pipe before and after shaping. Figure 6A Among them, before shaping, the total volume V0 of the rounding area at the top of the branch pipe includes the volume V1 of the part in contact with the branch pipe punch 4 and the volume V2 of the rounding part. Among them, the calculation formula for the volume V1 of the part in contact with the branch pipe punch 4 is as follows:

[0105]

[0106] The volume V2 of the rounding part is the product of the surface area of the rounding part and the average wall thickness of the branch pipe. Among them, the surface area of the rounding part can be regarded as the surface area of a rotating surface formed by rotating a quarter circle around an axis for one week. The calculation formula for the surface area A of the rotating surface is as follows:

[0107]

[0108] Among them, h(x) is the curve equation corresponding to the rounding arc. The coordinate origin corresponding to this curve equation is on the axis of the branch pipe cavity 5, and its expression is:

[0109]

[0110] Derive h(x) to obtain h′(x):

[0111]

[0112] Substitute it into the calculation formula of A to obtain:

[0113]

[0114] Then the calculation formula for the volume V2 of the rounding part is as follows:

[0115]

[0116] Then the calculation formula for the total volume V0 of the rounding area at the top of the branch pipe is as follows:

[0117]

[0118] In the above formula, R1 is the radius of the contact surface between the top of the branch pipe and the branch pipe punch 4, t is the average wall thickness of the branch pipe; and t is a set value, and R1 can be calculated according to the inner diameter of the branch pipe cavity 5 and the rounding size r.

[0119] Refer to Figure 6B As shown, the calculation formula for the volume V3 of the top of the branch pipe after back pressure shaping is as follows:

[0120] V3 = 2πRHt + π(R - t) 2 t

[0121] Wherein, R is 1 / 2 of the outer diameter of the branch pipe, that is, 1 / 2 of the inner diameter of the branch pipe cavity 5, and H is the height of the top of the branch pipe after backpressure.

[0122] According to the principle of constant volume of plastic deformation, V0 is equal to V3, and the calculation formula for the height H of the top of the branch pipe after backpressure is as follows:

[0123]

[0124] The distance h of the punch backpressure is the difference between the fillet radius r before backpressure and the height H of the top part of the branch pipe after backpressure, and the calculation formula is as follows:

[0125]

[0126] The present invention uses the method of backpressing the branch punch 4 for shaping, which not only reduces the demand for the maximum internal pressure of the equipment during the entire forming process, but also realizes effective feeding in the direction of the branch pipe; and the present invention not only improves the average wall thickness and material utilization rate of the branch pipe area, but also further increases the height of the straight wall area of the branch pipe, providing strong support for the overall optimization of product quality.

[0127] Specific examples are applied in the present invention to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A control system for high pressure forming of pipe fittings, characterized in that: comprising a first sensor, a second sensor, a third sensor and a controller; The first sensor, the second sensor and the third sensor are embedded in the side wall of the branch pipe cavity and / or in the branch pipe punch; The first sensor, the second sensor and the third sensor are respectively used to measure the distance to the surface of the bulging area of ​​the tube, and the three measuring points on the surface of the bulging area corresponding to the first sensor, the second sensor and the third sensor are not on a straight line; The controller is connected to the first sensor, the second sensor and the third sensor, and is used to determine the bulging curvature of the bulging area according to the measurement values ​​of the first sensor, the second sensor and the third sensor.

2. The control system according to claim 1, characterized in that: The first sensor is embedded in the branch pipe punch, and the detection direction of the first sensor is along the axial direction of the branch pipe cavity; The second sensor and the third sensor are both embedded in the side wall of the branch pipe cavity at one end close to the main pipe cavity, and the connecting line of the detection directions of the second sensor and the third sensor intersects perpendicularly with the axis of the branch pipe cavity.

3. The control system according to claim 1, characterized in that: It also includes a fourth sensor, wherein a plurality of the fourth sensors are embedded inside the side wall of the branch pipe cavity in a direction parallel to the axis of the branch pipe cavity, and the plurality of the fourth sensors are respectively used to measure the distance to the fillet surface of the top of the branch pipe; The detection directions of the plurality of fourth sensors are parallel and all intersect the axis of the branch pipe cavity at right angles, or the detection directions of the plurality of fourth sensors are parallel and all tilt from the transmitting end to the direction of the axis of the branch pipe cavity toward the direction close to the main pipe cavity; The controller is connected to the plurality of fourth sensors and is used to determine the size of the fillet at the top of the branch pipe according to the measurement values ​​of the plurality of fourth sensors.

4. The control system according to claim 3, characterized in that: Two assembly grooves are arranged in the side wall of the branch pipe cavity, and a plurality of the fourth sensors arranged in a direction parallel to the axis of the branch pipe cavity are arranged in both assembly grooves, and the plurality of the fourth sensors in the two assembly grooves are staggered in a direction parallel to the axis of the branch pipe cavity; and / or The plurality of fourth sensors are arranged at equal intervals along an axial direction parallel to the branch pipe cavity.

5. A method for controlling high pressure forming of pipe fittings, using the high pressure forming control system of any one of claims 1 to 4, characterized in that: The following steps are involved: When the tube is in the free expansion stage, the first sensor, the second sensor and the third sensor embedded in the side wall of the branch tube cavity and / or the branch tube punch respectively measure the distance to the surface of the expansion area of ​​the tube; Determine the relative positions of three measuring points on the surface of the bulging area according to the relative positions and measurement values ​​of the first sensor, the second sensor and the third sensor; Determining the bulging curvature of the bulging area according to the relative positions of the three measuring points; The three measurement points on the surface of the bulging area corresponding to the first sensor, the second sensor and the third sensor are not on a straight line.

6. The control method according to claim 5, characterized in that: A plurality of fourth sensors are embedded inside the side wall of the branch tube cavity along an axial direction parallel to the branch tube cavity, and the method further includes: When the pipe is in the branch pipe forming stage, using a plurality of the fourth sensors to respectively measure the distance to the rounded corner surface of the top of the branch pipe; Determine a plurality of distance values ​​between the inner wall surface of the branch tube cavity and the rounded corner surface of the top of the branch tube along the detection direction of the fourth sensor according to the measurement values ​​of the plurality of fourth sensors; Determine the size of the fillet at the top of the branch pipe according to the plurality of distance values ​​and the corresponding spacings between the plurality of fourth sensors; When the pipe is in the shaping stage, the back pressure distance of the branch pipe punch is determined according to the fillet size of the branch pipe top; A supporting internal pressure is applied inside the tube, and the branch pipe punch is moved along the direction toward the main pipe cavity by the back pressure distance.

7. The control method according to claim 5, characterized in that: After the step of determining the bulging curvature of the bulging area according to the relative positions of the three measuring points, the method further comprises: comparing the bulging curvature with a preset curvature value; If the bulging curvature is greater than the preset curvature value, reducing the forming internal pressure of the tube; If the bulging curvature is smaller than the preset curvature value, the forming internal pressure of the tube is increased.

8. The control method according to claim 6, characterized in that: After the step of determining the size of the fillet at the top of the branch pipe according to the plurality of distance values ​​and the corresponding spacings between the plurality of fourth sensors, the method further comprises: Comparing the size of the fillet at the top of the branch pipe with a preset interval; If the size of the rounded corner at the top of the branch pipe is smaller than the minimum value of the preset interval, the retreat speed of the branch pipe punch is increased and / or the material feeding amount of the main pipe punch is reduced; If the size of the rounded corner at the top of the branch pipe is greater than the maximum value of the preset interval, the retreat speed of the branch pipe punch is reduced and / or the material replenishment amount of the main pipe punch is increased.

9. The control method according to claim 6, characterized in that: The detection directions of the plurality of fourth sensors are parallel and perpendicularly intersect the axis of the branch pipe cavity. The plurality of fourth sensors are arranged at equal intervals in a direction parallel to the axis of the branch pipe cavity. The radius r1 of the fillet at the top of the branch pipe is determined according to the plurality of distance values ​​and the corresponding intervals d1 between the plurality of fourth sensors. The calculation formula is as follows: Wherein, n is the number of the fourth sensors measuring the fillet of the top of the branch pipe; i=1, 2, ..., n; X n is the nth distance value; Or the detection directions of the plurality of fourth sensors are parallel and are all inclined at an angle of 45° from the transmitting end to the direction of the axis of the branch pipe cavity toward the direction close to the main pipe cavity, and the plurality of fourth sensors are arranged at equal intervals along the direction parallel to the axis of the branch pipe cavity; the radius r2 of the fillet at the top of the branch pipe is calculated according to the plurality of distance values ​​and the corresponding intervals d2 between the plurality of fourth sensors, and the calculation formula is as follows: Wherein, m is the number of the fourth sensors measuring the fillet of the top of the branch pipe; j=1, 2, ..., m; X m is the mth distance value.

10. The control method according to claim 6, characterized in that: The back pressure distance h of the branch pipe punch is determined according to the fillet size r of the branch pipe top, and the calculation formula is as follows: Wherein, R1 is the radius of the contact surface between the top of the branch pipe and the branch pipe punch, R is half of the outer diameter of the branch pipe, and t is the average wall thickness of the branch pipe.

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