High-pressure forming die in rectangular pipe capable of being embedded with sensor

Abstract

A high-pressure forming die in a rectangular pipe capable of being embedded with a sensor comprises an upper die and a lower die, and a pipe fitting cavity is formed after the upper die and the lower die are assembled. Sensors are arranged on the wall of a cavity of the pipe fitting, and the sensors are arranged at the first die attaching position of the pipe fitting, the last die attaching position of the pipe fitting, the maximum die attaching pressure position of the pipe fitting, the maximum die attaching pressure generation position of the pipe fitting and the maximum expansion rate position of the pipe fitting in the internal high-pressure forming process correspondingly. The method is used for collecting wall surface change information of key positions in the pipe forming process. Through the mold and the sensor embedded in the mold, the wall surface change information of the key position in the high-pressure forming process in the pipe fitting can be obtained in real time, the controllability of internal high-pressure equipment is improved, and a foundation is laid for real-time adjustment of a loading path and other forming optimization operations.

Description

Technical Field

[0001] The invention relates to a forming die, in particular to a rectangular tube inner high pressure forming die capable of embedding a sensor. Background Art

[0002] Internal high pressure forming, also known as pipe hydraulic forming, is an advanced manufacturing technology for hollow variable cross-section lightweight components characterized by lightweight and integration. Currently, it is mainly based on carbon steel, special steel, stainless steel, aluminum alloy, copper alloy, etc. The internal high pressure forming process mainly includes the main steps of mold closing, sealing, water injection, pressurization and axial material feeding, and mold opening and taking out parts. The initial pipe produces plastic deformation under the combined action of internal pressure and axial horizontal thrust, expands to fit the mold, and finally forms the required component. In the internal high pressure forming process, the design of the loading curve is a key factor related to the quality of pipe forming. During the internal high pressure forming process of pipe fittings, since the mold is closed, in order to obtain pipe fittings with good forming quality, it is necessary to obtain a relatively good loading path before the forming begins to meet the needs.

[0003] Defects and shortcomings of the existing technology: At present, in the process of high pressure forming, the loading curve in the forming stage is the key factor affecting the quality of pipe forming. The internal pressure and axial feed rate must be coordinated and matched. If the internal pressure is too high, the pipe wall will become thinner or even crack; if the axial force is too large or too small, the pipe blank in the mold will be lifted or wrinkled. Whether the product is qualified depends largely on this stage. High pressure forming of pipe fittings is generally performed by setting a fixed loading path, and the equipment is pressurized and fed according to the loading path. Once the equipment starts running, the loading curve cannot be modified according to the row status of the pipe fittings. However, due to the problem of tube blank production accuracy, the same batch of tube blanks may have different lengths, which will cause cracking and wrinkling defects in the formed pipe fittings. The adjustment of the loading path needs to be determined according to the forming state of the pipe fittings. However, since the mold is sealed during the hydraulic forming process of the pipe fittings, the wall information of the pipe during the forming process is difficult to obtain and the feedback is insufficient, resulting in the inability to form a closed-loop control system. It is difficult to form a closed-loop control system, which is not conducive to the control and adjustment of the forming process, thereby causing problems such as poor control performance of the equipment, accuracy, and low success rate of sample development. Summary of the invention

[0004] In order to improve the control performance of the high pressure forming machine for tubes and obtain more forming feedback data, the traditional idea of ​​solidifying the loading curve is abandoned. A mold system with sensors is designed to collect the wall change information at key positions in the tube forming process in real time, so that the wall information at key positions can be visualized and the collected data can be used for the feedback control system to form a control closed loop, providing a data basis for real-time adjustment of the loading path.

[0005] The purpose of the present invention is to provide a rectangular tube high pressure forming die that can be embedded with a sensor, through which the wall surface change information of key positions in the process of high pressure forming of the tube can be obtained in real time. The present invention obtains the wall surface change information such as the first and last film sticking positions and the maximum film sticking force in the process of tube forming through finite element simulation of rectangular tubes, and selects displacement sensors, pressure sensors and contact sensors based on this, respectively obtaining the completion signal information of the tube diameter expansion displacement, die sticking pressure and the last die sticking position in the process of tube forming; the mold structure is designed according to the shape size structure and application characteristics of the selected sensor, and the sensor is embedded in the mold to establish a mold monitoring system; in the process of high pressure forming of the tube, the wall deformation information of the tube in the mold can be transmitted to the controller through the sensor, and then the real-time forming state of the tube can be obtained, and these data can be visualized or used as feedback to adjust the loading path, improve the controllability of the internal high pressure equipment, and lay the foundation for real-time adjustment of the loading path and other forming optimization operations.

[0006] The technical solution to solve the above problem is: a rectangular tube internal high-pressure forming mold in which a sensor can be embedded, comprising an upper mold and a lower mold, wherein the upper mold and the lower mold are combined to form a cavity of the tube, and a sensor is arranged on the cavity wall of the tube. The sensors are respectively arranged at the first mold-applying position of the tube, the last mold-applying position of the tube, the position of the maximum mold-applying pressure of the tube, the position where the maximum mold-applying pressure of the tube occurs, and the position where the expansion rate of the tube is the largest during the internal high-pressure forming process, and are used to collect wall change information at key positions during the tube forming process.

[0007] Its further technical solution is: during the internal high pressure forming process, the first die-attaching position of the pipe, the last die-attaching position of the pipe, the position of the maximum die-attaching pressure of the pipe and the position where the maximum die-attaching pressure of the pipe occurs can be determined through the finite element simulation analysis results of the pipe.

[0008] A further technical solution is: the sensor includes a displacement sensor, a pressure sensor and a contact sensor; the displacement sensor is installed at the position where the expansion rate of the tube is the largest during the internal high pressure forming process, and is used to measure the tube diameter deformation displacement during the tube expansion stage; the pressure sensor is installed at the first and last mold-applying positions of the tube during the internal high pressure forming process, and is used to measure the film-applying pressure during the mold-applying stage; the contact sensor is installed at the maximum mold-applying pressure of the tube during the internal high pressure forming process and at the position where it occurs, and is used to measure the complete mold-applying completion signal.

[0009] A further technical solution is: according to the external dimensions, structure and application characteristics of the selected sensor, a mounting slot for the sensor is reserved on the mold, and the mounting slot is used to fix the sensor.

[0010] A further technical solution is: a lower mold positioning groove is provided in the lower mold 4, and an upper mold positioning pin with a rounded corner is provided on the upper mold, and the upper mold positioning pin corresponds to the lower mold positioning groove.

[0011] A further technical solution is: the measuring range of the displacement sensor is 10 mm and the accuracy is 0.01 mm; the measuring range of the pressure sensor is 0-5 T; and the contact sensor is a dynamic touch sensor.

[0012] Due to the adoption of the above technical solution, the high pressure forming die for rectangular tubes in which sensors can be embedded in the present invention has the following beneficial effects compared with the prior art: The present invention preliminarily obtains the maximum deformation of the pipe during the internal high pressure forming process (that is, the maximum deformation is the deformation at the position with the maximum expansion rate of the pipe), the maximum deformation position (that is, the maximum deformation position is the position with the maximum expansion rate of the pipe), the maximum film-sticking pressure, and the first and last die-sticking positions through finite element simulation analysis of typical pipe fittings, so as to prepare for the subsequent sensor arrangement positions, and then considers the communication with the internal high pressure equipment control system to be coordinated, selects qualified displacement sensors (10mm range, accuracy of 0.01mm), pressure sensors (0-5T range) and contact sensors (dynamic touch type), which can respectively measure the pipe diameter deformation displacement in the expansion stage of the pipe fitting, the film-sticking pressure in the die-sticking stage, and the pressure drop in the mold-sticking stage. Force and complete mold forming completion signal are used to monitor the morphological changes of the entire pipe forming process; the sensor signal can be converted into a digital signal for display or feedback control through the analog-to-digital conversion module, so that the deformation state of the pipe during the internal high-pressure forming process can be visualized and controllable. These feedback information can be used to further improve and refine the internal high-pressure forming process control, especially to provide a reliable basis for the process regulation of the loading path; in the present invention, a sensor installation slot is reserved on the mold, which ensures the strength and sealing of the mold while ensuring the normal operation and signal acquisition of the sensor. The mold is provided with an upper mold positioning pin that acts as a guide column, further ensuring the mold fit between the upper and lower molds.

[0013] The technical features of a rectangular tube high pressure forming die capable of embedding a sensor according to the present invention will be further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the lower mold structure and sensor installation of the present invention; Figure 2 It is a schematic diagram of the upper mold structure of the present invention; Figure 3 It is a schematic diagram of the installation of the upper and lower molds of the present invention; Figure 4 Finite element simulation for high pressure forming of rectangular tube Figure 1 ; Figure 5 Finite element simulation for high pressure forming of rectangular tube Figure 2 ; Figure 6 Finite element simulation for high pressure forming of rectangular tube Figure 3 .

[0015] In the figure: 1-contact sensor; 2-displacement sensor; 3-lower mold positioning groove; 4-lower mold; 5-mold base; 6, 8-pressure sensor mounting plate; 7-pressure sensor; 9-lower mold cavity; 10-upper mold positioning pin; 11-upper mold cavity; 12-pressure sensor mounting groove; 13-upper mold; 14-displacement sensor mounting groove; 15-contact sensor mounting groove.

[0016] A-the first mold-attaching position of the pipe fitting, B-the last mold-attaching position of the pipe fitting, C-the position of the maximum mold-attaching pressure of the pipe fitting, D-the position where the maximum mold-attaching pressure of the pipe fitting occurs, and E-the position where the expansion rate of the pipe fitting is the largest. DETAILED DESCRIPTION

[0017] A rectangular tube internal high pressure forming die in which a sensor can be embedded comprises an upper die 13 and a lower die 4. The upper die 13 and the lower die 4 are combined to form a tube cavity. The tube cavity comprises an upper die cavity 11 and a lower die cavity 9. The upper die cavity 11 and the lower die cavity 9 cooperate to form the tube cavity. A sensor is arranged on the cavity wall of the tube. According to the results of the finite element simulation analysis of the tube, the first and last die positions of the tube during the internal high pressure forming process, the maximum die pressure and its occurrence position are obtained. At the position where the tube expansion rate is the largest (see Figure 4 ).

[0018] The sensors are arranged at the first die-attaching position A of the pipe during the internal high-pressure forming process, the last die-attaching position B of the pipe, the maximum die-attaching pressure position C of the pipe, the maximum die-attaching pressure position D of the pipe, and the position E of the maximum expansion rate of the pipe, respectively, to collect the wall surface change information of the key positions during the pipe forming process. Figure 4 , Figure 5 , Figure 6 There are 4 first mold-sticking positions A, 4 last mold-sticking positions B, 4 maximum mold-sticking pressure positions C, 4 maximum mold-sticking pressure positions D, and the position E with the largest expansion rate of the pipe is one circle in the middle of the pipe.

[0019] The sensor includes a displacement sensor 2, a pressure sensor 7 and a contact sensor 1; the displacement sensor 2 is installed at the position E where the expansion rate of the tube is the largest during the internal high pressure forming process, and is used to measure the tube diameter deformation displacement during the tube expansion stage; the pressure sensor 7 is installed at the first and last mold-attaching positions of the tube during the internal high pressure forming process, and is used to measure the film-attaching pressure during the mold-attaching stage; the contact sensor 1 is installed at the maximum mold-attaching pressure of the tube during the internal high pressure forming process and its occurrence position, and is used to measure the complete mold-attaching forming completion signal.

[0020] How to install the sensor: Reserve a sensor installation slot on the mold based on the selected sensor's dimensions, structure, and application characteristics. The installation slot is used to fix the sensor. For example: Figures 1 to 3 As shown: A displacement sensor mounting groove 14 is provided in the upper and lower molds for placing and fixing the displacement sensor 2. The displacement sensor 2 has an accuracy of 0.01 mm and a total range of 10 mm, which meets the requirements for pipe diameter change during the hydroforming process of the rectangular tube. Its main function is to obtain the diameter change information of the pipe fitting during the bulging stage of the internal high-pressure forming. A pressure sensor 7 is arranged at the position where the pipe fitting is first attached to the mold. According to the external dimensions and working mode of the pressure sensor 7, a working contact hole of the pressure sensor 7 is provided in the cavity 9 of the lower mold 4. The working contact of the pressure sensor 7 just fits the mold. The pressure sensor 7 is fixed in the pressure sensor mounting groove 7 of the lower mold through the pressure sensor mounting plates 6 and 8 to ensure that it is rigidly connected to the mold. The range of the pressure sensor 7 is 0-5T, which meets the maximum stress requirement during the forming process of the pipe fitting. Its main function is to obtain the mold pressure information of the pipe fitting during the shaping stage after the mold is attached. The contact sensor 1 is arranged at the minimum fillet radius of the pipe fitting. According to the external size structure and working mode of the contact sensor 1, a contact sensor installation groove 15 is opened for installing the contact sensor 1. Because this place is generally the last mold-attaching position and the forming difficulty is the greatest, the contact sensor 1 is a dynamic touch sensor. The dynamic touch contact sensor can sensitively detect and reflect whether the pipe fitting is completely attached to the mold. If the contact sensor 1 at this place is actuated, it proves that the pipe fitting has been shaped at this time, representing a forming completion signal.

[0021] In this way, these three sensors can monitor the state changes of the entire forming process of the pipe in the mold during internal high-pressure forming, and transmit this information to the controller of the internal high-pressure forming equipment as a feedback signal or display output. This information can then be used to adjust and improve the loading path of the equipment during the forming process in real time, such as reducing the internal pressure if the mold pressure is too high, increasing the internal pressure and reducing the feed if the pipe diameter displacement is insufficient or the forming end signal is not triggered, and other flexible loading path control strategies.

[0022] In addition, in order to ensure the fit between the upper and lower molds, a lower mold positioning groove 3 with a diameter of 16 mm is provided in the lower mold 4, and an upper mold positioning pin 10 with rounded corners is designed on the upper mold 13, and the upper mold positioning pin 10 corresponds to the lower mold positioning groove 3. If there is a slight deviation in the assembly of the upper and lower molds, the upper mold positioning pin will be introduced into the positioning groove of the lower mold first when the molds are closed, driving the upper mold and the lower mold to be completely aligned, further ensuring the matching accuracy of the mold and reducing the difficulty of mold assembly.

[0023] The parts not involved in the present invention are the same as the prior art or can be implemented by the prior art. The above content is a further detailed description of the present invention in combination with specific preferred implementation modes. It cannot be determined that the specific implementation of the present invention is limited to the records of the above embodiments. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the patent protection scope of the present invention determined by the submitted claims.

Claims

1. A high pressure forming die for a rectangular tube in which a sensor can be embedded, comprising an upper die and a lower die, wherein the upper die and the lower die are combined to form a cavity for the tube, characterized in that: Sensors are provided on the cavity wall of the pipe fitting, and the sensors are respectively arranged at the first mold-applying position of the pipe fitting, the last mold-applying position of the pipe fitting, the position of the maximum mold-applying pressure of the pipe fitting, the position where the maximum mold-applying pressure of the pipe fitting occurs, and the position where the expansion rate of the pipe fitting is the largest during the internal high-pressure forming process, and are used to collect wall surface change information at key positions during the pipe forming process.

2. A rectangular tube high pressure forming die capable of embedding a sensor according to claim 1, characterized in that: During the internal high pressure forming process, the first die-attaching position of the tube, the last die-attaching position of the tube, the position of the maximum die-attaching pressure of the tube and the position where the maximum die-attaching pressure of the tube occurs can be determined through the finite element simulation analysis results of the tube.

3. A rectangular tube high pressure forming die capable of embedding a sensor according to claim 2, characterized in that: The sensor includes a displacement sensor, a pressure sensor and a contact sensor; the displacement sensor is installed at the position where the expansion rate of the tube is the largest during the internal high pressure forming process, and is used to measure the tube diameter deformation displacement during the tube expansion stage; the pressure sensor is installed at the first and last mold-applying positions of the tube during the internal high pressure forming process, and is used to measure the film-applying pressure during the mold-applying stage; the contact sensor is installed at the maximum mold-applying pressure of the tube during the internal high pressure forming process and at the position where it occurs, and is used to measure the signal of the completion of complete mold-applying forming.

4. A rectangular tube high pressure forming die capable of embedding a sensor according to claim 3, characterized in that: A mounting slot for the sensor is reserved on the mold according to the shape, size, structure and application characteristics of the selected sensor, and the mounting slot is used to fix the sensor.

5. The high pressure forming die for rectangular tubes capable of embedding sensors according to claim 1, characterized in that: A lower mold positioning groove is provided in the lower mold, and an upper mold positioning pin with a rounded corner is provided on the upper mold, and the upper mold positioning pin corresponds to the lower mold positioning groove.

6. A rectangular tube high pressure forming die capable of embedding a sensor according to claim 2, characterized in that: The displacement sensor has a measuring range of 10 mm and an accuracy of 0.01 mm; the pressure sensor has a measuring range of 0-5 T; and the contact sensor is a dynamic touch sensor.

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