A self-adaptive welding method for a special bracket for freeze-drying barrels

Abstract

The present invention proposes an adaptive welding method for a freeze-drying barrel special bracket, which belongs to the field of laser welding. The adaptive welding method for a freeze-drying barrel special bracket of the present invention includes assembling an adaptive welding system for the freeze-drying barrel bracket, calculating the change in welding gap, setting the welding gap range and selecting the diameter of the welding wire, installing the workpiece and adjusting the gap, and starting welding. The adaptive welding system for the non-uniform gap interface includes a rotating component, a clamping component, a workbench, a multi-axis moving device, a laser wire-filling welding system, a visual detection system and a control system; the size of the welding interface gap between the freeze-drying barrel and the bracket is detected in real time by a visual detection sensor, and the moving speed of the multi-axis moving device is adjusted in real time to drive the laser welding gun of the laser wire-filling welding system to realize a welding process with adaptive welding speed, so that the wire filling and heat input at different positions of the welding interface match the gap size, and the non-uniform gap interface is welded once to obtain a stable and reliable weld.

Description

Technical Field

[0001] The invention relates to the field of laser welding, and in particular to an adaptive welding method for a special bracket for a freeze-drying barrel. Background Art

[0002] The freeze-drying barrels for small food freeze dryers are usually cylindrical in shape, and are generally equipped with several external mounting brackets to connect and fix the freeze-drying barrels to the inside of the freeze-drying machine shell. The welding strength of the brackets for freeze-drying barrels is one of the key factors in the overall quality of the freeze-drying machine. It must be ensured that the freeze-drying machine will not break due to vibration or aging during transportation and use, and that the freeze-drying barrels will not tilt or fall abnormally in the shell, so as to ensure the long-term reliability of the freeze-drying machine.

[0003] The welding of the freeze-drying barrel and its special bracket usually adopts the laser wire-filling automatic welding process. Laser wire-filling welding fills and fuses the gap between the cylindrical surface of the freeze-drying barrel and the rectangular plane of the bracket through the melting of the welding wire to achieve the connection between the two. The existing freeze-drying barrel bracket welding technology uses constant welding parameters throughout the welding process. However, the cylindrical surface of the freeze-drying barrel and the rectangular plane of the bracket form a non-uniform gap welding interface. The constant parameter welding process leads to differences in the welding quality of each point on the weld, which reduces the overall welding quality of the interface. Since a layer of thermal insulation foam layer will be injection molded on the outside of the barrel in the subsequent process of the freeze dryer, the welding interface of the bracket will be completely covered. Therefore, once the freeze-drying barrel bracket breaks after the whole machine is delivered to the customer, the bracket connection interface will not be able to be repaired on-site, and the whole machine needs to be replaced, which brings great losses to customers and manufacturers.

[0004] Therefore, there is an urgent need for a variable parameter welding method adapted to a freeze-drying barrel bracket to ensure that the welding quality of the freeze-drying barrel bracket is effective and reliable. Summary of the invention

[0005] The object of the present invention is to provide a self-adaptive welding method for a freeze-drying barrel special bracket to solve the above-mentioned prior art problems.

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

[0007] A method for adaptive welding of a special bracket for a freeze-drying barrel comprises the following steps:

[0008] S1 assembly freeze drying barrel bracket adaptive welding system;

[0009] The freeze-drying barrel support adaptive welding system includes a rotating assembly, a pressing assembly, a workbench, a multi-axis moving device, a laser wire-filling welding system, a visual inspection system and a control system;

[0010] The rotating assembly comprises a rotating unit, a disc and a bracket clamping module. The rotating unit is mounted on the workbench. A flange and bolts are provided on the upper part of the rotating unit to connect with the disc, driving the disc to rotate in a vertical direction. An annular groove for positioning the freeze-drying barrel is provided on the disc. A plurality of bracket clamping modules are provided on the disc along the circumference of the freeze-drying barrel installation position.

[0011] The bracket clamping module includes a rotary clamping cylinder, a pressure arm, a bracket pressing block and a bracket supporting block, and a plurality of the bracket supporting blocks are arranged on the disc, and a rotary clamping cylinder is arranged on the disc behind the bracket supporting block, and the rotary clamping cylinder is vertically connected to one end of the pressure arm through an output shaft, and the other end of the pressure arm is connected to the bracket pressing block below, and the rotary clamping cylinder provides power for the output shaft, and the output shaft drives the pressure arm to drive the bracket pressing block to rise or fall or reverse, until the bracket pressing block matches the bracket supporting block to press the bracket to be welded;

[0012] One end of the pressing assembly is fixed on a mounting frame mounted on the workbench surface, and the other end is provided with a freely rotatable pressing plate, the pressing plate is opposite to the disc of the rotating assembly and forms an installation space for the freeze-drying barrel;

[0013] The laser wire welding system includes a laser welding gun and a laser controller; the visual inspection system includes a visual sensor and a visual controller; the multi-axis moving device is mounted on the workbench and slides relative to the mounting frame, and the laser welding gun and the visual sensor are both fixed to the execution end of the multi-axis moving device with bolts; the rotating unit, the multi-axis moving device, the laser wire welding system and the visual inspection system are all electrically connected to the control system.

[0014] S2 calculates the change in welding gap;

[0015] The freeze drying barrel and the bracket are fixed to form a welding interface with a non-uniform gap. The maximum gap change value Δl is calculated using the following formula max :

[0016]

[0017] 0<Δl max ≤1.2

[0018] Where Δl max The maximum change value of the gap, mm; D is the outer diameter of the freeze-drying barrel cylinder, mm; w is the width of the bracket, mm; S3 sets the welding gap range and the selected wire diameter;

[0019] According to the material properties of the freeze drying barrel and the support and the maximum change value of the gap Δl max , determine the minimum gap value lmin , we can get the maximum gap l max = l min +Δl max and gap variation range (l min , l max );Then select the wire diameter specification according to the gap size range;

[0020] S4 installs the workpiece and adjusts the gap;

[0021] The freeze-drying barrel is installed and fixed on the disc with its opening facing downward, and after positioning, it is compressed and fixed using the clamping assembly; the bracket is pre-installed on the bracket support block, and the position of the bracket support block on the disc is adjusted using a feeler gauge so that the relative position of the bracket and the freeze-drying barrel conforms to the gap variation range specified in step S3 of the method, and then the relative position of the bracket pressing block on the pressing arm is adjusted accordingly so that the bracket pressing block tightly presses the pre-installed bracket.

[0022] S5 starts welding;

[0023] The control system controls the multi-axis moving device to drive the laser welding gun and the visual sensor to move to the starting position of the welding interface and start the welding process; the visual sensor acquires the welding interface image in real time and transmits it to the visual controller, and the visual controller continuously identifies the welding gap value l of the welding point of the laser welding gun and transmits it to the control system;

[0024] Under the same welding quality, the welding gap l and welding power P are inversely correlated with the welding speed v. The larger the welding gap l, the larger the required welding wire filling amount and the input welding heat. When the welding power P and the welding wire diameter d remain unchanged, the smaller the required welding speed v. The larger the welding power P, the greater the heat input to the weld per unit time when the welding gap l and the selected welding wire diameter d remain unchanged. The smaller the welding speed v required under the premise of ensuring a constant welding effect. The welding diameter d is positively correlated with the welding speed v. The larger the welding diameter d is, the higher the weld filling efficiency per unit time when the welding power P and the welding gap l remain unchanged. The shorter the welding gun stays on the same length of weld, the larger the required welding speed v. After welding and demolition tests, the welding speed v satisfies the following quantitative relationship with the welding gap l, welding power P and welding wire diameter d:

[0025]

[0026] The unit of welding speed v is mm / s, the unit of welding wire diameter d is mm, the unit of laser power P is W, and k1, k2, and k3 are adjustment coefficients;

[0027] The control system has a preset corresponding calculation logic, and calculates the required welding speed in real time according to the welding gap, welding power and welding wire diameter, and controls the multi-axis moving device to drive the laser welding gun to move at the corresponding speed. The welding power and welding wire diameter are set before welding begins, and the welding speed is dynamically adjusted according to the welding gap identified in real time until the welding process of the interface is completed. The control system controls the rotating assembly to move to the welding position of the next bracket, and starts a new round of welding process, repeating the cycle until all brackets are welded.

[0028] Furthermore, in the adaptive welding method for the freeze-drying barrel-specific bracket, the rotating assembly and the pressing assembly described in step S1 are respectively provided in two sets each and are arranged adjacent to each other on the workbench.

[0029] Furthermore, in the self-adaptive welding method for the freeze-drying barrel-specific bracket, the bracket clamping modules described in step S1 are provided in four sets on each set of the rotating assembly and are arranged in four equal parts around the freeze-drying barrel.

[0030] Furthermore, in the self-adaptive welding method for freeze-drying barrel bracket, the welding gap variation range determination principle in step S3 is: when the maximum gap variation value Δl max When ≤0.2mm, the minimum gap value l min Set to 0.2mm; when 0.2mm<Δl max When the minimum gap value is l min Set to 0.1mm.

[0031] Furthermore, in the self-adaptive welding method for freeze-drying barrel bracket, the principle for selecting the welding diameter specification in step S3 is: when the maximum gap l max ≤0.30mm, the welding wire specification should be 0.8mm in diameter; when 0.30mm<l max ≤0.40mm, the welding wire specification should be 1.0mm in diameter; when 0.40mm<l max ≤0.55mm, the welding wire diameter is 1.2mm; when 0.55mm<l max When welding, the welding wire specification is selected with a diameter of 1.6m.

[0032] The beneficial effects of the present invention are as follows:

[0033] 1. Through the visual inspection system, the gap changes of the welding interfaces of the freeze-drying barrel and its bracket during the welding process are detected in real time, and the real-time changes of the laser welding speed are controlled. The existing technology of welding the freeze-drying barrel bracket at a constant speed is changed to realize the corresponding low-speed welding at the position with a larger gap, so that the filling amount is sufficient and the weld is full without defects; the corresponding high-speed welding is realized at the position with a larger gap, so that the heat and filling amount provided are reduced accordingly, ensuring that the connection between the barrel wall and the bracket is not deformed or overburned, and ensuring the quality of the weld is good.

[0034] 2. The quantitative relationship between welding speed and welding gap provided by this method has multiple adjustment coefficients. As the production process data continues to accumulate, the manufacturer can continuously optimize and adjust the quantitative relationship to achieve the goal of continuously seeking a better welding speed while meeting the welding quality, thereby continuously improving the production efficiency of the bracket welding process and continuously improving the economic efficiency of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of the self-adaptive welding method for the freeze-drying barrel bracket of the present invention;

[0036] Figure 2 This is a schematic structural diagram of an adaptive welding system for a freeze-drying barrel support according to an embodiment of the present invention;

[0037] Figure 3 It is a structural schematic diagram of a bracket clamping module according to an embodiment of the present invention;

[0038] Figure 4 The relationship curve diagram of the welding gap l and the welding speed v in the embodiment of the present invention;

[0039] In the figure, 1-rotation assembly, 11-rotation unit, 12-disc, 13-bracket clamping module, 131-rotation clamping cylinder, 132-pressing arm, 133-bracket pressing block, 134-bracket supporting block, 2-pressing assembly, 3-workbench, 4-multi-axis moving device, 5-laser welding gun, 6-visual sensor, 7-freeze drying barrel, 8-bracket. DETAILED DESCRIPTION

[0040] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments given here are only used to illustrate and explain the present invention, and cannot be used to limit the present invention.

[0041] It should be noted that many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention may also have other implementations and variations thereof. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0042] like Figures 1 to 4As shown, a method for adaptive welding of a special bracket for a freeze-drying barrel comprises the following steps:

[0043] S1 assembly freeze drying barrel bracket adaptive welding system;

[0044] The freeze-drying barrel support adaptive welding system includes a rotating component 1, a pressing component 2, a workbench 3, a multi-axis moving device 4, a laser wire-filling welding system, a visual inspection system and a control system;

[0045] The rotating assembly 1 includes a rotating unit 11, a disc 12 and a bracket clamping module 13. The rotating unit 11 is mounted on the workbench 3. The upper part of the rotating unit 11 is provided with a flange and bolts connected to the disc 12, driving the disc 12 to rotate forward and reverse around the vertical direction; the disc 12 is provided with an annular groove for positioning the freeze-drying barrel 7, and a plurality of bracket clamping modules 13 are arranged on the disc 12 along the circumference of the installation position of the freeze-drying barrel 7;

[0046] The bracket clamping module 13 includes a rotary clamping cylinder 131, a pressure arm 132, a bracket pressing block 133 and a bracket supporting block 134. Several bracket supporting blocks 134 are arranged on the disc 12. A rotary clamping cylinder 131 is arranged on the disc 12 behind the bracket supporting block 134. The rotary clamping cylinder 131 is vertically connected to one end of the pressure arm 132 through an output shaft, and the other end of the pressure arm 132 is connected to the bracket pressing block 133 below. The rotary clamping cylinder 131 provides power for the output shaft, and the output shaft drives the pressure arm 132 to drive the bracket pressing block 133 to rise or fall or rotate forward and reverse until the bracket pressing block 133 matches the bracket supporting block 134 to press the bracket to be welded.

[0047] One end of the pressing assembly 2 is fixed to a mounting frame mounted on the workbench 3, and the other end is provided with a freely rotatable pressing plate, which is opposite to the disc 12 of the rotating assembly 1 and forms an installation space for the freeze-drying barrel 7.

[0048] The laser wire-filling welding system includes a laser welding gun 5 and a laser controller; the visual inspection system includes a visual sensor 6 and a visual controller; the multi-axis moving device 4 is mounted on a workbench and slides relative to the mounting frame, and the laser welding gun 5 and the visual sensor 6 are both fixed to the execution end of the multi-axis moving device 4 with bolts; the rotating unit 11, the multi-axis moving device 4, the laser wire-filling welding system and the visual inspection system are all electrically connected to the control system.

[0049] S2 calculates the change in welding gap;

[0050] It is planned to weld a non-uniform gap interface formed by a freeze-drying barrel with an outer diameter D of 328 mm and a bracket with a width w of 26 mm. The maximum gap change value Δl of the welded interface with a non-uniform gap formed after the freeze-drying barrel and the bracket are fixed separately max for:

[0051]

[0052] Right now Satisfy the effective range.

[0053] S3 sets the welding gap range and the selected welding wire diameter;

[0054] The freeze-drying barrel and the bracket are made of 304 stainless steel, and stainless steel welding wire is selected as the welding filler material. max =0.516mm, set the minimum gap between the freeze drying barrel and the bracket l min is 0.1 mm, and the corresponding maximum gap value l max = l min +Δl max =0.616mm and the gap variation range is between 0.1mm and 0.616mm, and a stainless steel welding wire with a diameter of 1.6mm is selected for welding accordingly.

[0055] S4 installs the workpiece and adjusts the gap;

[0056] The freeze-drying barrel 7 is fixed on the disc 12 with its opening facing downward, and after positioning, it is compressed using the compression assembly 2; the bracket 8 is pre-installed on the bracket support block 134, and the position of the bracket support block 134 on the disc 12 is adjusted using a feeler gauge so that the relative position of the bracket 8 and the freeze-drying barrel 7 conforms to the gap size of 0.1 mm to 0.616 mm specified in step S3 of this embodiment, and then the relative position of the bracket pressing block 133 to the pressing arm 132 is adjusted accordingly so that the bracket pressing block 133 tightly compresses the pre-installed bracket 8.

[0057] S5 starts welding;

[0058] The control system controls the multi-axis moving device 4 to drive the laser welding gun 5 and the visual sensor 6 to move to the starting position of the welding interface and start the welding process; the visual sensor 6 obtains the welding interface image in real time and transmits it to the visual controller, and the visual controller continuously identifies the welding interface gap value l at the point pointed by the laser welding gun 5 and transmits it to the control system; the control system is preset with calculation logic, which calculates the required welding speed according to the welding gap, welding power and welding wire diameter in real time, dynamically adjusts the moving speed of the multi-axis moving device 4, and drives the laser welding gun 5 to execute the corresponding welding speed v. The welding speed v satisfies the following quantitative relationship:

[0059]

[0060] The unit of welding speed v is mm / s, the unit of welding wire diameter d is mm, the unit of laser power P is W, and k1, k2, and k3 are adjustment coefficients;

[0061] When welding a freeze-drying barrel with an outer diameter of 328 mm and a bracket with a width of 26 mm, a 1.6 mm diameter welding wire is selected and the laser power is set to 200 W. The welding and demolition tests are performed to determine the quality-compliant welding speed corresponding to uniform gap welds with different gap sizes, as shown in the following table:

[0062] Serial number Welding gap l (unit: mm) Welding speed v (unit: mm / s) 1 0.10 6.2 2 0.15 5.3 3 0.20 4.7 4 0.25 4.1 5 0.30 3.5 6 0.35 3.1 7 0.40 2.7 8 0.45 2.3 9 0.50 2.1 10 0.55 1.9 11 0.60 1.7 12 0.62 1.6

[0063] Using the above data to fit the quantitative formula, it is determined that the adjustment system k1, k2, and k3 are 0.40, 1223.90, and -3.02, respectively, that is, the welding speed v satisfies the following quantitative formula:

[0064]

[0065] In step S3, the welding gap variation range between the barrel 7 and the bracket 8 is set to 0.1mm to 0.616mm. According to the quantitative formula, the welding speed is dynamically adjusted between 1.60mm / s and 6.12mm / s. The welding gap is the largest at the starting and ending positions of the welding interface, and a lower welding speed is used accordingly to ensure sufficient input of heat and wire material, so that the wire material fully fills the gap and fuses well with the parent material, thereby ensuring good mechanical properties of the weld at the corresponding position; the welding gap is the smallest in the middle of the welding interface, and a higher welding speed is used accordingly to avoid excessive heat input, effectively control the heat-affected zone of the parent material to remain in an appropriate range, and also ensure that the weld at the corresponding position has good mechanical properties.

[0066] The multi-axis moving device 4 completes the interface welding process according to the above speed control logic. The control system controls the rotating component 1 to rotate to the welding position of the next bracket 8 and starts a new round of welding process, repeating the cycle until all brackets are welded.

[0067] It should be understood that the above embodiment is only one embodiment of the present invention, and there are many other embodiments and variations thereof based on the present invention; the variations and modifications made by ordinary technicians in this industry through the present invention without making pioneering innovations all fall within the scope of protection of the present invention.

Claims

1. A method for adaptive welding of a freeze-drying barrel bracket, characterized in that The following steps are involved: S1 assembly freeze drying barrel bracket adaptive welding system; The freeze-drying barrel support adaptive welding system includes a rotating assembly, a pressing assembly, a workbench, a multi-axis moving device, a laser wire-filling welding system, a visual inspection system and a control system; The rotating assembly comprises a rotating unit, a disc and a bracket clamping module. The rotating unit is mounted on the workbench. A flange and bolts are provided on the upper part of the rotating unit to connect with the disc, driving the disc to rotate in a vertical direction. An annular groove for positioning the freeze-drying barrel is provided on the disc. A plurality of bracket clamping modules are provided on the disc along the circumference of the freeze-drying barrel installation position. The bracket clamping module includes a rotary clamping cylinder, a pressure arm, a bracket pressing block and a bracket supporting block. Several bracket supporting blocks are arranged on the disc. A rotary clamping cylinder is arranged on the disc behind the bracket supporting block. The rotary clamping cylinder is vertically connected to one end of the pressure arm through an output shaft. The other end of the pressure arm is connected to the bracket pressing block below. The rotary clamping cylinder provides power for the output shaft. The output shaft drives the pressure arm to drive the bracket pressing block to rise or fall or reverse in both directions until the bracket pressing block matches the bracket supporting block to press the bracket to be welded. One end of the pressing assembly is fixed on a mounting frame mounted on the workbench surface, and the other end is provided with a freely rotatable pressing plate, the pressing plate is opposite to the disc of the rotating assembly and forms an installation space for the freeze-drying barrel; The laser wire welding system includes a laser welding gun and a laser controller; the visual inspection system includes a visual sensor and a visual controller; the multi-axis moving device is mounted on the workbench and slides relative to the mounting frame, the laser welding gun and the visual sensor are both fixed to the execution end of the multi-axis moving device, the laser welding gun is mounted on the execution end, and the laser welding gun realizes movement of multiple degrees of freedom through the multi-axis moving device; the rotating unit, the multi-axis moving device, the laser controller and the visual controller are all electrically connected to the control system; S2 calculates the change in welding gap; The freeze drying barrel and the bracket are fixed to form a welding interface with a non-uniform gap. The maximum gap change value Δl is calculated using the following formula max : 0<Δl max ≤1.2 Where Δl max The maximum change value of the gap, mm; D is the outer diameter of the cylinder of the freeze-drying barrel, mm; w is the width of the bracket, mm; S3 sets the welding gap range and the selected welding wire diameter; According to the material properties of the freeze drying barrel and the bracket and the maximum change value of the gap Δl max , determine the minimum gap value l min , we can get the maximum gap l max = l min +Δl max and gap variation range (l min , l max );Then select the wire diameter specification according to the gap variation range; S4 installs the workpiece and adjusts the gap; The freeze-drying barrel is fixed on the disc with its opening facing downward, and after positioning, it is pressed and fixed using the pressing assembly; the bracket is pre-installed on the bracket support block, and the position of the bracket support block on the disc is adjusted using a feeler gauge so that the relative position of the bracket and the freeze-drying barrel conforms to the gap variation range specified in step S3 of the method, and then the relative position of the bracket pressing block on the pressing arm is adjusted accordingly so that the bracket pressing block tightly presses the pre-installed bracket; S5 starts welding; The control system controls the multi-axis moving device to drive the laser welding gun and the visual sensor to move to the starting position of the welding interface and start the welding process; the visual sensor obtains the welding interface image in real time and transmits it to the visual controller, and the visual controller continuously identifies the welding gap value l of the welding point of the laser welding gun and transmits it to the control system; the control system is preset with calculation logic, which calculates the required welding speed according to the welding gap, welding power and welding wire diameter in real time, dynamically adjusts the moving speed of the multi-axis moving device, and drives the laser welding gun to execute the corresponding welding speed v, and the welding speed v satisfies the following quantitative relationship: The unit of welding speed v is mm / s, d is the wire diameter in mm, P is the laser power in W, and k1, k2, and k3 are adjustment coefficients; Before welding, the welding and demolition tests are performed to determine the quality-compliant welding speed corresponding to uniform gap welds of different gap sizes, and the fitting quantitative formula is used to determine the adjustment system k1, k2, and k3; The multi-axis moving device completes the interface welding process according to the above speed control logic, and the control system controls the rotating component to rotate to the welding position of the next bracket and starts a new round of welding process, repeating the cycle until all brackets are welded.

2. The method for self-adapting welding of a freeze-drying barrel bracket according to claim 1, characterized in that: The rotating assembly and the pressing assembly described in step S1 are respectively provided in two sets, and are arranged adjacent to each other on the workbench.

3. The method for self-adaptive welding of a freeze-drying barrel bracket according to claim 1, characterized in that: The support clamping modules described in step S1 are provided in four sets on each set of the rotating assembly and are arranged in four equal parts around the freeze-drying barrel.

4. The method for self-adaptive welding of a freeze-drying barrel bracket according to claim 1, characterized in that: The minimum gap value determination principle in step S3 is: when the maximum gap change value Δl max When ≤0.2mm, the minimum gap value l min Set to 0.2mm; when Δl max >0.2mm, the minimum gap value l min Set to 0.1mm.

5. The method for self-adaptive welding of a freeze-drying barrel bracket according to claim 1, characterized in that: The principle for setting the welding diameter specification in step S3 is: when the maximum gap l max ≤0.30mm, the welding wire specification should be 0.8mm in diameter; when 0.30mm<l max ≤0.40mm, the welding wire specification should be 1.0mm in diameter; when 0.40mm<l max ≤0.55mm, the welding wire diameter is 1.2mm; when 0.55mm<l max When welding, the wire diameter is 1.6mm.

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