Welding clamp and welding method for sickbed frame

Abstract

The invention relates to the technical field of welding, in particular to a welding clamp and a welding method for a sickbed frame, and aims to solve the technical problem that in the existing process steps for welding the sickbed frame, the ineffective working time is relatively high. The welding clamp comprises a bottom supporting piece, at least six supporting parts are arranged on the bottom supporting piece, and the supporting parts are distributed on the periphery and the middle of the bottom supporting piece; the pressing assembly is arranged on the bottom supporting piece and comprises a plurality of pressing parts in one-to-one correspondence with all the supporting parts; the rotating end of the rotating assembly is connected with the bottom supporting piece; wherein the supporting part on the periphery of the bottom supporting piece is located in the middle of the periphery of the bottom supporting piece. All the workpieces are pressed at a time through the pressing part of the pressing assembly, and therefore time consumed when the workpieces are clamped is shortened. The bottom supporting piece is directly driven to rotate by 180 degrees through the rotating assembly, the workpiece is driven to rotate together, a welding seam at the bottom of the bed frame is turned over to the top face, and therefore invalid working hours generated by turning over the workpiece are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of bed frame welding, and in particular to a welding fixture and a welding method for a hospital bed frame. Background Art

[0002] During the production of the bed frame, the support structure at the bottom of the bed board (such as the attached Figure 1 The welding fixture system commonly used in the industry currently has the following technical defects: Inefficient collaborative control of multiple actuators: Existing fixtures are equipped with independent air cylinders or hydraulic cylinders as driving sources for each workpiece. When forming a cross-shaped frame, more than ten execution units need to be controlled point by point through PLC. This discrete drive method not only leads to complex logic levels of the control program (multi-axis synchronization parameters and anti-interference strategies need to be set), but also increases the overall clamping and positioning time by about 40% due to differences in response delays of each actuator. In addition, the deployment of a large number of solenoid valve groups and sensors significantly increases the system failure rate and the maintenance cost remains high.

[0003] Lack of automation in the double-sided welding process: The current process adopts a step-by-step welding mode of "top first, then flip". Specifically, after the welding robot completes the top weld, the operator needs to use the lifting equipment to flip the connected mesh-shaped frame (usually 2m×1m in size) 180° to expose the bottom weld. This process has a double efficiency bottleneck: on the one hand, the mass of the frame assembly can reach more than 20kg after rigid connection, and manual flipping takes more than 5 minutes; on the other hand, the frame is prone to distortion during the flipping process, resulting in an average positioning deviation of 0.5-1.2mm during the secondary clamping, which directly affects the consistency of the bottom welding quality.

[0004] The above technical bottlenecks have seriously restricted the mass production efficiency of hospital bed brackets. According to industry statistics, the single-piece production cycle of traditional processes is about 65% longer than the theoretical value, of which fixture preparation and workpiece flipping account for more than 72% of invalid working hours. Therefore, it is urgent to develop new clamping systems and welding processes to break through the technical limitations of the existing production model. Summary of the invention

[0005] In view of the technical problem that in the existing process steps of welding hospital bed frames, the invalid working hours account for a high proportion, the present invention provides a welding fixture and a welding method for a hospital bed frame, by placing all the workpieces on all the supporting parts at one time, and then clamping all the workpieces at one time through the clamping part of the clamping assembly, thereby reducing the time consumed in clamping the workpieces; then in the welding process, after the top surface is welded, the bottom support is directly driven to rotate 180° through the rotating assembly, driving the workpiece to rotate together, and flipping the weld at the bottom of the bed frame to the top surface, thereby reducing the invalid working hours caused by flipping the workpiece.

[0006] The technical solution of the present invention is: A welding fixture for a hospital bed frame, used for clamping six workpieces in a mesh shape, comprising: A bottom support member, wherein the bottom support member is provided with at least six support portions distributed around and in the middle of the bottom support member; A clamping assembly, provided on the bottom support member, comprising a plurality of clamping parts corresponding to all the support parts one by one, the clamping parts being movable relative to the support parts, and the clamping parts being used to fix the workpiece; A rotating assembly, the rotating end of which is connected to the bottom support member and can drive the bottom support member to rotate at least 180°; Wherein, the supporting parts around the bottom supporting member are located in the middle position around the bottom supporting member.

[0007] Optionally, the support portion includes a support plate and a positioning plate that are arranged perpendicular to each other; The pressing portion can be close to or away from the supporting plate.

[0008] Optionally, the pressing part includes a side movable part, a middle movable part, an end movable part, a side driving part and a pressing driving part; The side movable member is dynamically connected to the side driving member; The middle movable member and the end movable member are dynamically connected to the pressing driving member.

[0009] Optionally, the side movable member comprises: A plurality of side pressure plates are slidably disposed on the bottom support member and correspond one-to-one to the support plates on both sides of the bottom support member; A plurality of driving rods are correspondingly arranged on each of the side pressure plates, and the ends of the driving rods are hinged to the side pressure plates; A pressure rod, both ends of which are respectively hinged to the end of one of the driving rods; Wherein, the side driving member is dynamically connected to the pressure rod and is used to drive the pressure rod to approach or move away from the bottom supporting member.

[0010] Optionally, eight supporting parts are provided on the bottom supporting member, two supporting parts are respectively provided on both sides of the bottom supporting member, and the two supporting parts are respectively close to two ends of the bottom supporting member; The side movable parts include four side pressure plates, four driving rods and two pressure rods; The side movable member also includes a connecting rod, two ends of the connecting rod are connected to the two pressure rods, and the middle part of the connecting rod is connected to the side driving member.

[0011] Optionally, the middle movable member includes a middle pressure plate, and the end movable member includes an end pressure plate; The middle pressing plate and the end pressing plates are both located on the same side of their corresponding supporting plates; The clamping driving member comprises a driving plate, and the middle pressing plate and the end pressing plates are both arranged on the driving plate.

[0012] Optionally, the rotating assembly includes a support frame and a servo motor; The two ends of the bottom support member are rotatably arranged on one of the support frames respectively, the servo motor is arranged on one of the support frames, and the output shaft of the servo motor is dynamically connected to one end of the bottom support member.

[0013] A welding method based on a welding fixture comprises the following steps: S10, placing six workpieces in six supporting parts, and pressing the six workpieces by a pressing assembly to form a mesh-shaped structure; S20, using a welding robot to perform multiple passes of welding on the joints of the six workpieces; S21. During the welding process, the arc sensor monitors the penetration depth in real time and controls the penetration amount to 85%-95% of the workpiece wall thickness, and automatically adjusts the welding speed or current when the penetration depth exceeds the threshold; S22, the connections of the four workpieces located around are welded in a boat-shaped position; S23, the joints between the two middle workpieces and the two side workpieces are welded in sections; S30, driving the bottom support member to rotate 180 degrees through the rotating assembly, and performing multiple passes of welding on the connection of the bottom surface of the bed frame using the method of steps S20 to S23; S40, after welding, the residual stress is eliminated by vibration aging equipment.

[0014] Optionally, in step S22, the welding parameters are dynamically adjusted according to the thickness of the pipe: the initial current is 140A, and the current is reduced by 2A after each welding of 10mm length until it drops to 130A; In step S23, after each welding section is completed, a local electromagnetic pulse treatment is applied to the weld area immediately, with a pulse frequency of 150-180 Hz and an energy density of 3-4 J / mm²; In the step S40, the frequency of the vibration aging equipment is 80 Hz for the first 10 minutes and 120 Hz for the last 15 minutes.

[0015] Optionally, in step S21, when the molten pool temperature exceeds 1600° C. or the penetration fluctuation exceeds ±0.1 mm, the welding speed and current are adjusted in real time, and the adjustment formula is: , in, , , is the actual temperature, is the target temperature, is the instantaneous change of the molten pool temperature, is the time interval; Adjusted current change Limited to ±10A.

[0016] Compared with the prior art, the present invention has the following beneficial effects: By placing all the workpieces on all the support parts at one time, and then clamping all the workpieces at one time through the clamping part of the clamping assembly, the time spent on clamping the workpieces is reduced; then in the welding process, after the top surface is welded, the bottom support is directly driven by the rotating assembly to rotate 180°, driving the workpieces to rotate together, and flipping the weld at the bottom of the bed to the top surface, thereby reducing the invalid working hours caused by flipping the workpiece.

[0017] Through this technical solution, the ineffective working hours can be reduced to 15%, and the production efficiency can be increased by nearly three times. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a three-dimensional structural schematic diagram of a hospital bed frame; Figure 2 It is a schematic diagram of the working state of the present invention; Figure 3 This is a schematic diagram of the clamping state of the welding fixture; Figure 4 It is a schematic diagram of the three-dimensional structure of the welding fixture; Figure 5 It is a schematic diagram of the assembly structure of the middle movable part, the end movable part and the pressing driving part; Figure 6 It is a schematic diagram of the assembly structure of the side movable part and the side driving part; Figure 7 It is a partial enlarged schematic diagram of the side movable parts; Figure 8 It is a process flow chart of the present invention.

[0020] Reference numerals: 100, workpiece; 110, side workpiece; 120, middle workpiece; 130, end workpiece.

[0021] 200, bottom support member; 210, support portion; 220, positioning rod; 211, end support portion; 212, middle support portion; 213, side support portion; 210-1, support plate; 210-2, positioning plate.

[0022] 300, pressing assembly; 310, pressing portion; 311, side movable part; 312, middle movable part; 313, end movable part; 314, side driving part; 315, pressing driving part; 316, slide rail; 311-1, side pressure plate; 311-2, driving rod; 311-3, pressure rod; 311-4, connecting rod; 312-1, middle pressure plate; 313-1, end pressure plate; 314-1, side hydraulic cylinder; 315-1, driving plate; 315-2, clamping hydraulic cylinder.

[0023] 400, rotating assembly; 410, supporting frame; 420, servo motor.

[0024] 500. Welding robot. DETAILED DESCRIPTION

[0025] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0026] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0027] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. Example

[0028] See also Figure 2 , Figure 3 and Figure 4 This embodiment discloses a welding fixture for a bed frame, which is used to clamp six workpieces 100 (the workpieces 100 are square tubes) and weld the six workpieces 100 according to the attached Figure 1 The mesh-shaped structure shown is clamped. Figure 1 As shown, the six workpieces 100 can be divided into three groups, each group having two workpieces 100 of equal length. For the convenience of subsequent description, the two longest workpieces 100 are defined as side workpieces 110, the two shortest workpieces 100 are defined as middle workpieces 120, and the remaining two workpieces 100 are defined as end workpieces 130.

[0029] The welding fixture includes a bottom support 200, a clamping assembly 300 and a rotating assembly 400. The bottom support 200 is used to support six workpieces 100, the clamping assembly 300 is used to fix the six workpieces 100 on the bottom support 200, and the rotating assembly 400 is used to directly drive the bottom support 200, the clamping assembly 300 and the six workpieces 100 to rotate 180 degrees.

[0030] Specifically, at least six support parts 210 are provided on the bottom support member 200, and at least one support part 210 is provided on each of the four sides of the bottom support member 200, and at least two support parts 210 are provided in the middle of the bottom support member 200. The support parts 210 at both ends of the bottom support member 200 are defined as end support parts 211, the support part 210 in the middle of the bottom support member 200 is defined as a middle support part 212, and the support parts 210 on both sides of the bottom support member 200 are defined as side support parts 213. When placing the workpieces 100 on the bottom support member 200, all the workpieces 100 are placed in the corresponding support parts 210 respectively.

[0031] The clamping assembly 300 is disposed on the bottom support member 200, and the clamping assembly 300 includes a plurality of clamping parts 310, and each support part 210 corresponds to a clamping part 310, and the clamping part 310 can move relative to the support part 210, so that the clamping part 310 is close to or away from the support part 210, thereby clamping or relaxing the workpiece 100 in the support part 210.

[0032] The rotating end of the rotating assembly 400 is dynamically connected to one end of the bottom support member 200 .

[0033] In this embodiment, all the workpieces 100 are placed on all the support parts 210 at one time, and then all the workpieces 100 are clamped at one time by the clamping parts 310 of the clamping assembly 300 , thereby reducing the time consumption in clamping the workpieces 100 .

[0034] Then during the welding process, after the welding robot 500 completes welding the top surface, it directly drives the bottom support 200 and the clamping assembly 300 to rotate 180° through the rotating end of the rotating assembly 400, driving all the workpieces 100 to rotate 180° together, and flipping the weld at the bottom of the bed frame to the top surface, thereby reducing the invalid working hours caused by flipping the workpiece 100.

[0035] Through this technical solution, the ineffective working hours can be reduced to 15%, and the production efficiency can be increased by nearly three times.

[0036] Preferably, the support portions 210 located around the bottom support member 200 are all located in the middle of the bottom support member 200 , so that all the connections of the workpieces 100 can be completely exposed to the environment, so as to facilitate welding operations on the connections of the workpieces 100 .

[0037] In one specific embodiment: See also Figure 4 , Figure 5 , Figure 6 and Figure 7 The support portion 210 includes a support plate 210-1 and a positioning plate 210-2, wherein the support plate 210-1 is installed on the bottom support member 200, and one end of the positioning plate 210-2 is fixedly connected to one end of the support plate 210-1, so that the positioning plate 210-2 and the support plate 210-1 form an L-shaped structure.

[0038] The pressing portion 310 of the pressing assembly 300 can slide on the supporting plate 210 - 1 and move toward or away from the positioning plate 210 - 2 .

[0039] During the actual placement of the workpiece 100, the bottom of the workpiece 100 contacts the support plate 210-1, and one side of the workpiece 100 contacts the positioning plate 210-2, so that the workpiece 100 can be quickly and preliminarily positioned through the L-shaped structure formed by the support plate 210-1 and the positioning plate 210-2.

[0040] In another specific embodiment: See also Figure 4 , Figure 5 , Figure 6 and Figure 7 The pressing part 310 includes a side movable part 311, a middle movable part 312, an end movable part 313, a side driving part 314 and a pressing driving part 315. The side movable part 311 corresponds to the side supporting part 213, the middle movable part 312 corresponds to the middle supporting part 212, and the end movable part 313 corresponds to the end supporting part 211.

[0041] The side driving member 314 is connected to the side movable member 311 by power, so that the side driving member 314 can directly drive the side movable member 311 to move closer to or away from the side support portion 213. The pressing driving member 315 is connected to both the middle movable member 312 and the end movable member 313 by power, so that the pressing driving member 315 can simultaneously drive the middle movable member 312 and the end movable member 313 to move the middle movable member 312 closer to or away from the middle support portion 212, and the end movable member 313 closer to or away from the end support portion 211.

[0042] In one preferred embodiment, see Figure 6 and Figure 7 The side movable member 311 includes a side pressure plate 311-1, a driving rod 311-2 and a pressure rod 311-3. The number of the side pressure plates 311-1 is the same as the number of the side support parts 213, and each side pressure plate 311-1 is arranged corresponding to a side support part 213. During installation, the side pressure plate 311-1 is slidably connected to the support plate 210-1 in the side support part 213, and is arranged parallel to the positioning plate 210-2 in the side support part 213.

[0043] A driving rod 311-2 is rotatably connected to the middle of one side of each side pressing plate 311-1 away from the positioning plate 210-2, one end of the driving rod 311-2 is connected to the side pressing plate 311-1, and the other end of the driving rod 311-2 is rotatably connected to one end of the pressing rod 311-3.

[0044] Among them, the rotation plane of the driving rod 311-2 is perpendicular to the plate surface of the support plate 210-1, the rotation axes at both ends of the driving rod 311-2 are parallel to each other, and the end of the driving rod 311-2 connected to the pressure rod 311-3 is set in an inclined direction and inclined in the direction away from the support plate 210-1 and the positioning plate 210-2.

[0045] The driving rod 311 - 2 and the side pressure plate 311 - 1 at both ends of the pressure rod 311 - 3 are symmetrically arranged. The driving end of the side driving member 314 is connected to the pressure rod 311 - 3 and is used to drive the pressure rod 311 - 3 to move closer to or away from the bottom support member 200 .

[0046] In another preferred embodiment, see Figure 4 and Figure 5 The middle movable member 312 includes a middle pressure plate 312-1, and the end movable member 313 includes an end pressure plate 313-1. The middle pressure plate 312-1 and the end pressure plate 313-1 are both located on the same side of the support plate 210-1 in the corresponding support portion 210. The clamping drive member 315 includes a drive plate 315-1, and the drive plate 315-1 is movably arranged on the bottom support member 200. The aforementioned middle pressure plate 312-1 and the end pressure plate 313-1 are both arranged on the drive plate 315-1, and the middle pressure plate 312-1 can be driven to approach or move away from the positioning plate 210-2 in the middle support portion 212 through the drive plate 315-1, and the end pressure plate 313-1 can also be driven to approach or move away from the positioning plate 210-2 in the end support portion 211.

[0047] In this embodiment, the side driving member 314 further includes a side hydraulic cylinder 314-1, and the piston rod end of the side hydraulic cylinder 314-1 is connected to the pressing rod 311-3. The pressing driving member 315 further includes a pressing hydraulic cylinder 315-2, and the piston rod end of the pressing hydraulic cylinder 315-2 is connected to the driving plate 315-1. At the same time, the side hydraulic cylinder 314-1 and the pressing hydraulic cylinder 315-2 are started and stopped synchronously.

[0048] The working principle of this embodiment is as follows: in the initial state, the distance between the side pressing plate 311-1 and the positioning plate 210-2 in the side supporting part 213 is greater than the width of the side workpiece 110. After the side workpiece 110 is placed on the side supporting part 213, the side hydraulic cylinder 314-1 is started to drive the pressing rod 311-3 to approach the bottom supporting member 200. At this time, the pressing rod 311-3 pushes the driving rod 311-2 to rotate, thereby pushing the side pressing plate 311-1 to slide on the supporting plate 210-1 through the driving rod 311-2, thereby achieving the clamping of the side workpiece 110.

[0049] In the initial state, the distance between the middle pressing plate 312-1 and the positioning plate 210-2 in the middle supporting part 212 is greater than the width of the middle workpiece 120, the distance between the end pressing plate 313-1 and the positioning plate 210-2 in the end supporting part 211 is greater than the width of the end workpiece 130, and the distance between the middle pressing plate 312-1 and the positioning plate 210-2 in the middle supporting part 212 is equal to the distance between the end pressing plate 313-1 and the positioning plate 210-2 in the end supporting part 211. When working, the middle workpiece 120 is placed on the middle supporting part 212, and the end workpiece 130 is placed on the end supporting part 211. Start the clamping hydraulic cylinder 315-2, and push the driving plate 315-1 through the piston rod of the clamping hydraulic cylinder 315-2, so that the middle pressing plate 312-1 and the end pressing plate 313-1 are directly driven by the driving plate 315-1 to clamp the corresponding workpiece 100 in the corresponding supporting part 210.

[0050] according to Figure 1 It can be known that the side surfaces of the two end workpieces 130 are in contact with the ends of the two side workpieces 110, and therefore, in the above-mentioned welding fixture, there is no positioning structure for the position of the end workpiece 130. Therefore, an L-shaped positioning rod 220 is respectively provided at both ends of the bottom support member 200 to determine the end position of the end workpiece 130. Generally speaking, the positioning rod 220 can be provided on one side of the end of the bottom support member 200, or can be symmetrically provided on both sides of the bottom support member 200, and can be selectively provided according to needs.

[0051] In another specific embodiment: Since the side workpiece 110 is relatively long, a side support portion 213 is provided to support the side workpiece 110, and the side workpiece 110 is prone to falling. Figure 4 and Figure 6 Two side support portions 213 are respectively arranged on both sides of the bottom support member 200 , so that a total of eight support portions 210 are arranged on the bottom support member 200 .

[0052] The above-mentioned side movable part 311 includes four side pressure plates 311-1, four driving rods 311-2 and two pressure rods 311-3. The four side pressure plates 311-1 are respectively arranged corresponding to the four side support parts 213, and the four driving rods 311-2 are respectively arranged corresponding to the four side pressure plates 311-1. The two ends of the two pressure rods 311-3 are respectively hinged to the end of a driving rod 311-2.

[0053] The side movable member 311 further comprises two connecting rods 311-4, the ends of the connecting rods 311-4 are respectively fixedly connected to the middle parts of the two pressure rods 311-3, and the two connecting rods 311-4 are arranged parallel to each other. The piston rod of the side hydraulic cylinder 314-1 is connected to the two connecting rods 311-4.

[0054] In this embodiment, the side hydraulic cylinder 314 - 1 drives the connecting rod 311 - 4 , and the connecting rod 311 - 4 drives the pressing rod 311 - 3 , thereby realizing the movement of the side pressing plate 311 - 1 .

[0055] Since there are four side support parts 213, the clamping force of a single side hydraulic cylinder 314-1 is limited. Therefore, a side hydraulic cylinder 314-1 can be set on each of the two connecting rods 311-4, and the piston rods of the two side hydraulic cylinders 314-1 can be moved synchronously to enhance the clamping force.

[0056] In another specific embodiment: See also Figure 6 and Figure 7 Since the side pressure plate 311-1 has a sliding motion relative to the support plate 210-1 in the side support portion 213, a slide rail 316 is set on the support plate 210-1 in the side support portion 213, and a slide groove matching the slide rail 316 is set at the bottom of the side pressure plate 311-1, so as to limit the movement trajectory of the side pressure plate 311-1.

[0057] In another specific embodiment: See also Figure 2 , Figure 3 and Figure 4 The rotating assembly 400 includes a support frame 410 and a servo motor 420, wherein the two ends of the bottom support member 200 are respectively rotatably arranged on the top of a support frame 410, the servo motor 420 is fixedly arranged on one of the support frames 410, and a reduction mechanism is arranged on the output shaft of the servo motor 420, and the output shaft of the servo motor 420 is dynamically connected to one end of the bottom support member 200 through the reduction mechanism.

[0058] In this embodiment, the rotation of the bottom support member 200 and all the workpieces 100 is controlled by a servo motor 420 .

[0059] In another specific embodiment: Since all the workpieces 100 are relatively heavy after being welded together, there is a risk that the workpieces 100 in the pressing portion 310 and the supporting portion 210 may fall off after being turned over.

[0060] In order to ensure that the workpiece 100 remains in a fixed position within the clamping portion 310 and the supporting portion 210, the top ends of the side pressure plates 311-1, the middle pressure plates 312-1 and the end pressure plates 313-1 are all designed to be L-shaped structures. Thus, after the workpiece is clamped, the L-shaped structure can cover part of the top surface of the workpiece 100. Furthermore, after flipping, the L-shaped structure can support the workpiece 100 and prevent it from falling. Example

[0061] See also Figure 8 This embodiment discloses a welding method based on the welding fixture described in the first embodiment, comprising the following steps: S10, placing six workpieces 100 in six supporting parts 210, and pressing the six workpieces 100 by the pressing assembly 300 to form a mesh-shaped structure; S20, using the welding robot 500 to perform multi-pass welding on the joints of the six workpieces 100; S21. During the welding process, the arc sensor is used to monitor the penetration depth in real time, and the penetration amount is controlled to be 85%-95% of the wall thickness of the workpiece 100, and the welding speed or current is automatically adjusted when the penetration depth exceeds a threshold value; S22. The connections of the four workpieces 100 located at the periphery are welded in a boat-shaped position; the welding parameters are dynamically adjusted according to the thickness of the pipe: the initial current is 140A, and the current is reduced by 2A after each welding length of 10mm until it drops to 130A.

[0062] S23. The connection between the two middle workpieces 100 and the two side workpieces 100 is welded in sections. After each section of welding is completed, a local electromagnetic pulse treatment is immediately applied to the weld area, with a pulse frequency of 150-180 Hz and an energy density of 3-4 J / mm².

[0063] S30, driving the bottom support member 200 to rotate 180° through the rotating assembly 400, and performing multiple passes of welding on the connection of the bottom surface of the bed frame using the method of steps S20 to S23; S40, after welding, the residual stress is eliminated by vibration aging equipment. The frequency of the vibration aging equipment is 80Hz for the first 10 minutes and 120Hz for the last 15 minutes.

[0064] Before step S10, the material is inspected and surface treated. The inspection includes checking the size, straightness and surface integrity of the workpiece 100. The workpiece 100 is required to have a size tolerance of ±0.5 mm, a wall thickness error of ≤0.1 mm, and no cracks or rust on the surface.

[0065] In addition, before step S10 , a weld may be selectively processed on the end of the workpiece 100 according to the wall thickness of the workpiece 100 .

[0066] When performing surface treatment, it is necessary to clean the rust layer, oil stains, etc. within 20mm of the weld area, and the cleanliness level should reach Sa2½ level (ISO 8501-1:2007) to expose the metallic luster in this area.

[0067] This step can improve assembly accuracy, reduce welding stress concentration, ensure weld fusion quality, and prevent pores and slag inclusions.

[0068] In step S10, two side workpieces 110 are placed in the side support parts 213 on both sides of the bottom support member 200, two end workpieces 130 are placed in the end support parts 211 at both ends of the bottom support member 200, and two middle workpieces 120 are placed in the two middle support parts 212 in the middle of the bottom support member 200. The two side workpieces 110 are parallel to each other, the two end workpieces 130 and the two middle workpieces 120 are in a parallel state, and the side workpieces 110 and the middle workpieces 120 are perpendicular. Through the layout design of the support part 210, the workpieces 100 are distributed in a mesh shape.

[0069] In step S21, when the molten pool temperature exceeds 1600°C or the penetration fluctuation exceeds ±0.1mm, the welding speed and current are adjusted in real time, and the adjustment formula is: , in, is the actual temperature, is the target temperature, is the instantaneous change of the molten pool temperature, that is, the change in temperature per unit time, is a small time interval. The above formula is essentially a simplified form of the proportional-derivative (PD) controller, and its general expression is: , in, , which is the difference between the actual temperature and the target temperature.

[0070] Proportional coefficient : Quickly respond to current temperature deviations (such as immediately reducing current when the molten pool is overheated).

[0071] Differential coefficient :Predict temperature change trends (such as suppressing current growth in advance when the temperature rises suddenly) to prevent overshoot.

[0072] Since the welding process is instantaneous and nonlinear, the integral term easily leads to cumulative errors (such as a small deviation over a long period of time causing a sudden change in current). Therefore, a proportional-derivative (PD) controller is preferably used to balance the response speed and stability.

[0073] in, , , the current change after adjustment Restricted to within the range.

[0074] The coefficient value is determined by welding test to determine the parameter range. When it is too high (>1.0), the current will fluctuate violently (±15A or more). When it is too low (<0.5), the probability of the molten pool temperature exceeding the standard will increase by 40% due to response delay. The introduction of proportional control reduces the temperature fluctuation by 30% (compared to pure proportional control).

[0075] Final Choice , ,at this time and The ratio is 4:1, which has been verified to be the optimal solution for high-speed operation of welding robots 500. The adaptability of workpieces with different wall thicknesses (1.5-4.0mm) is increased by 50% without reprogramming.

[0076] According to the melting characteristics of welding wire (such as ER70S-6 (AWS A5.18), each 10A current affects the deposition rate by about 1.2mm / s), limiting the adjustment range can avoid the loss of control of the molten pool. Verification shows that under the ±10A limit, the weld formation factor (melt width / melt depth) is stable at 1.2-1.5, which meets the standard requirements of AWS D1.1.

[0077] After verification, the PD control of this solution and the traditional PID control have obvious optimization effects in terms of temperature exceeding rate, penetration fluctuation, weld qualification rate, etc., as shown in the following table: , The penetration depth (physical quantity) and the penetration temperature (thermodynamic quantity) are controlled and dynamically coupled through the same model, which is more accurate than the control technology using a single variable for transmission.

[0078] Due to the introduction of differential terms, the system can maintain penetration stability when the gap between the workpiece 100 and the assembly parts fluctuates (±0.1mm), and the anti-interference ability is improved by about 50% compared with the traditional method.

[0079] After step S21, step S22 and step S23, according to ASTM E112 standard, the grain size of the weld is increased from level 5 to level 7 (microhardness increased by 20%). The width of the heat affected zone is reduced to 1.2 mm (2.0 mm in the traditional process), reducing the performance loss of the workpiece 100.

[0080] After step S40, the residual stress elimination rate of the welded bed frame is increased from 75% to 95% through the vibration aging equipment, and the frame flatness is ≤1mm / m (conventional process ≤3mm / m). In addition, compared with the single-frequency solution, the vibration aging time is shortened by 30% and the energy consumption is reduced by 40%.

[0081] The above-mentioned embodiments only express the specific implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A welding fixture for a bed frame, used to clamp six workpieces in a mesh shape, characterized in that: The welding fixture comprises: A bottom support member, wherein the bottom support member is provided with at least six support portions distributed around and in the middle of the bottom support member; A clamping assembly, provided on the bottom support member, comprising a plurality of clamping parts corresponding to all the support parts one by one, the clamping parts being movable relative to the support parts, and the clamping parts being used to fix the workpiece; A rotating assembly, the rotating end of which is connected to the bottom support member and can drive the bottom support member to rotate at least 180°; Wherein, the supporting parts around the bottom supporting member are located in the middle position around the bottom supporting member.

2. The welding fixture for a hospital bed frame according to claim 1, characterized in that: The support portion includes a support plate and a positioning plate which are arranged perpendicular to each other; The pressing portion can be close to or away from the supporting plate.

3. The welding fixture for the bed frame according to claim 2, characterized in that: The clamping part includes a side movable part, a middle movable part, an end movable part, a side driving part and a clamping driving part; The side movable member is dynamically connected to the side driving member; The middle movable member and the end movable member are dynamically connected to the pressing driving member.

4. The welding fixture for the bed frame according to claim 3, characterized in that: The side movable member comprises: A plurality of side pressure plates are slidably disposed on the bottom support member and correspond one-to-one to the support plates on both sides of the bottom support member; A plurality of driving rods are correspondingly arranged on each of the side pressure plates, and the ends of the driving rods are hinged to the side pressure plates; A pressure rod, both ends of which are respectively hinged to the end of one of the driving rods; Wherein, the side driving member is dynamically connected to the pressure rod and is used to drive the pressure rod to approach or move away from the bottom supporting member.

5. The welding fixture for the bed frame according to claim 4, characterized in that: The bottom support member is provided with eight support parts, two support parts are respectively provided on both sides of the bottom support member, and the two support parts are respectively close to two ends of the bottom support member; The side movable parts include four side pressure plates, four driving rods and two pressure rods; The side movable member also includes a connecting rod, two ends of the connecting rod are connected to the two pressure rods, and the middle part of the connecting rod is connected to the side driving member.

6. The welding fixture for the bed frame according to claim 3, characterized in that: The middle movable member includes a middle pressure plate, and the end movable member includes an end pressure plate; The middle pressing plate and the end pressing plates are both located on the same side of their corresponding supporting plates; The clamping driving member comprises a driving plate, and the middle pressing plate and the end pressing plates are both arranged on the driving plate.

7. The welding fixture for a hospital bed frame according to claim 1, characterized in that: The rotating assembly includes a support frame and a servo motor; The two ends of the bottom support member are rotatably arranged on one of the support frames respectively, the servo motor is arranged on one of the support frames, and the output shaft of the servo motor is dynamically connected to one end of the bottom support member.

8. A welding method based on the welding fixture according to any one of claims 1 to 7, characterized in that: The following steps are involved: S10, placing six workpieces in six supporting parts, and pressing the six workpieces by a pressing assembly to form a mesh-shaped structure; S20, using a welding robot to perform multiple passes of welding on the joints of the six workpieces; S21. During the welding process, the arc sensor monitors the penetration depth in real time and controls the penetration amount to 85%-95% of the workpiece wall thickness, and automatically adjusts the welding speed or current when the penetration depth exceeds the threshold; S22, the connections of the four workpieces located around are welded in a boat-shaped position; S23, the joints between the two middle workpieces and the two side workpieces are welded in sections; S30, driving the bottom support member to rotate 180 degrees through the rotating assembly, and performing multiple passes of welding on the connection of the bottom surface of the bed frame using the method of steps S20 to S23; S40, after welding, the residual stress is eliminated by vibration aging equipment.

9. The welding method according to claim 8, characterized in that: In step S22, the welding parameters are dynamically adjusted according to the thickness of the pipe: the initial current is 140A, and the current is reduced by 2A after each welding of 10mm length until it drops to 130A; In step S23, after each welding section is completed, a local electromagnetic pulse treatment is applied to the weld area immediately, with a pulse frequency of 150-180 Hz and an energy density of 3-4 J / mm²; In the step S40, the frequency of the vibration aging equipment is 80 Hz for the first 10 minutes and 120 Hz for the last 15 minutes.

10. The welding method according to claim 8, characterized in that: In step S21, when the molten pool temperature exceeds 1600°C or the penetration fluctuation exceeds ±0.1mm, the welding speed and current are adjusted in real time, and the adjustment formula is: , in, , , T 实际 is the actual temperature, T 目标 is the target temperature, d(T 实际 ) is the instantaneous change of the molten pool temperature, and dt is the time interval; Adjusted current change Limited to ±10A.

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