A welding gun head suitable for small-angle narrow slits

Abstract

The present invention discloses a welding gun head suitable for small-angle narrow slits. The inner diameter of the air outlet of the protective sleeve of the welding gun head is 9-11 mm, and the outer diameter is 12-14 mm; a plurality of circular holes evenly distributed in the circumferential direction are provided at the cross-section of the protective sleeve close to the air outlet of the protective sleeve. On the premise of ensuring that the length of the welding wire extending out of the contact tip is qualified, the present invention reduces the diameter of the hollow frustum of the protective sleeve, so that the welding gun head can extend deeper into the weld; noise reduction circular holes are provided on the protective sleeve, and the size and position of the noise reduction circular holes punched on the protective sleeve are optimized and calculated according to the design requirements of the total sound power of the jet noise, and then the punching is accurately implemented, so that the total sound power of the jet noise accurately meets the design requirements, reduces the speed and pressure of the argon jet at the air outlet of the protective sleeve, eliminates the discrete noise caused by the huge instantaneous pressure change in the jet mixing zone, and effectively eliminates the high-frequency noise during the welding process.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding, and particularly relates to a welding gun head suitable for small-angle narrow slits. Background Art

[0002] When welding is in progress, the aluminum wire and the workpiece to be welded are melted at high temperature, and the melted aluminum liquid is easily oxidized. The generation of scale and other bad substances will reduce the weld quality. The high-pressure and high-speed inert argon gas flowing between the contact tip and the protective sleeve isolates the air around the melting zone, so that oxidation does not occur during a series of welding processes such as melting and crystallization. The welding gun head includes a protective sleeve and a contact tip. During use, the welding wire is installed on the contact tip and extends out of the protective sleeve. Normally, the inner diameter of the existing protective sleeve air outlet is about 13 mm, and the outer diameter is 16 mm. The length of the welding wire extending out of the contact tip is between 10 and 15 mm. The end face of the contact tip is flush with the end face of the protective sleeve. The argon gas flows out at high speed between the contact tip and the protective sleeve to isolate oxygen.

[0003] When the welding angle formed between the workpieces to be welded is between the conventional 70-90 degrees, the welding gun protective sleeve can complete the welding task. However, when the welding angle formed between the workpieces to be welded is less than the conventional angle, such as when the angle is less than 65 degrees, in order to prevent the protective sleeve from contacting the workpiece to be welded (contact will cause the welding wire to fail to strike an arc), the conventional method is to move the welding gun outwards by a certain distance. However, in such a case, in order to enable the welding wire to strike an arc normally, the length of the welding wire extending out of the contact tip will exceed 20 mm. And when the welding wire extends out of the contact tip too long, the welding process will be extremely unstable. Because the welding wire will bend when it extends too long, and the deviation of the bend has complex non-linear characteristics. Such a bend will cause a deviation of 2 to 4 mm in the position of the outermost end point of the welding wire, resulting in a deviation in the repeated positioning between the welding wire and the weld. For a given welding gun head manipulator and welding system, the deviation of each arrival at the specified position should not exceed 0.5 mm. When the manipulator is not equipped with a weld detection system, it will not cause the manipulator arm to follow due to the bending of the welding wire, thus resulting in a deviation of the welding point, that is, the welding point is not at the center of the weld. When the welding point deviates, the welding quality will decline significantly, and defects such as partial welding, weld fracture, and uneven penetration will occur. Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies of the prior art and propose a welding gun head suitable for small-angle narrow slits. On the premise of ensuring that the length of the welding wire extending out of the contact tip is qualified, the diameter of the hollow frustum of the protective sleeve is reduced, so that the welding gun head can penetrate deeper into the weld, and a noise reduction round hole is provided on the protective sleeve. The size and distribution of the round hole are designed according to the design requirements of the total sound power of the jet noise to eliminate the high-frequency noise during the welding process.

[0005] A welding gun head applicable to small-angle narrow slits of the present invention includes a gas channel, a round hole, a contact tip, and a protective sleeve; the contact tip and the protective sleeve are fixed by a connecting member, and a gas channel is provided between the side surface of the contact tip and the protective sleeve; the inner diameter of the protective sleeve at the air outlet is 9-11 mm, and the outer diameter is 12-14 mm; a plurality of round holes evenly distributed in the circumferential direction are opened at the cross-section of the protective sleeve close to the air outlet of the protective sleeve.

[0006] Preferably, the specific process of reducing the total sound power of the jet noise by opening the round holes to meet the design requirements is as follows:

[0007] The total sound power P of the jet noise T is calculated as follows:

[0008]

[0009] wherein, U1 is the jet velocity at the air outlet of the protective sleeve, ρ0 is the ambient air density, ρ s is the instantaneous air density in the hollow frustum region of the protective sleeve, D1 is the inner diameter of the protective sleeve at the air outlet, K L is an experimental constant, taking 3×10 -5 , and c0 is the speed of sound.

[0010] Suppose the flow rate of the air flow before passing through the round holes on the protective sleeve is Q, the flow rate of the air flow after passing through the round holes on the protective sleeve is Q1, and the sum of the flow rates of each round hole is Q n , then there is:

[0011] Q = Q1 + Q n

[0012] It is obtained that:

[0013] Q1 = Q - Q n = Q - n * r 2 * π * U x (1)

[0014] wherein, n is the number of round holes, and r is the radius of the round hole;

[0015] Since Q is known, according to Q, the cross-sectional area of the section where the centers of the round holes on the protective sleeve are located, and the cross-sectional area of the section on the contact tip aligned with the centers of the round holes, the air flow velocity U at the round holes is solved x as follows:

[0016]

[0017] wherein, the diameter D of the cross-section of the protective sleeve at a distance x from the air outlet of the protective sleeve x= [(D2 - D1)·x] / H + D1, where x is the distance between the cross-section where the centers of the circular holes are located and the air outlet of the protective sleeve, D2 is the inner diameter of the cylinder of the protective sleeve, and H is the height of the hollow frustum of the protective sleeve; the cross-sectional diameter d at the position x from the air outlet of the protective sleeve of the conductive nozzle x = [(d2 - d1)·x] / h + d1, where h is the height of the frustum part of the conductive nozzle, d1 is the cross-sectional diameter at the position where the conductive nozzle is aligned with the air outlet of the protective sleeve, and d2 is the diameter of the cylindrical part of the conductive nozzle.

[0018] By combining Equation (1) and Equation (2), the flow rate Q1 of the air flow after passing through the circular holes on the protective sleeve is obtained. Combining the cross-sectional area at the air outlet of the protective sleeve and the cross-sectional area at the position where the conductive nozzle is aligned with the air outlet of the protective sleeve, the jet velocity U1 at the air outlet of the protective sleeve is solved as follows:

[0019]

[0020] According to the total sound power P of the jet noise within the known design range T , after obtaining the design range of U1, combining Formula (1), Formula (2), Formula (3), and the relationship D x = [(D2 - D1)·x] / H + D1 and the relationship d x = [(d2 - d1)·x] / h + d1, by setting the number of circular holes n, the radius r of the circular holes, and the distance x between the cross-section where the centers of the circular holes are located and the air outlet of the protective sleeve, the value of U1 is made to meet the requirements of the specific design range, so that the total sound power P of the jet noise T meets the requirements of the design range.

[0021] More preferably, measure the total sound power P T ' of the jet noise of the existing welding gun head model, and combine the jet velocity U1' at the air outlet of the protective sleeve of the existing welding gun head model and the inner diameter D1' at the air outlet of the protective sleeve of the existing welding gun head model. According to the expression of the ratio of P T to P T ', calculate the design range of the jet velocity U1 at the air outlet of the protective sleeve that should be achieved when meeting the design range of the total sound power P of the jet noise; the expression of the ratio of the total sound power P of the jet noise T to P T ' is as follows: T The beneficial effects of the present invention are as follows:

[0022]

[0023] The beneficial effects of the present invention are as follows:

[0024] On the premise of ensuring that the length of the welding wire extending out of the contact tip is qualified, by reducing the diameter of the hollow frustum of the protective sleeve, the welding gun head can extend deeper into the weld. However, when using a protective sleeve with only the diameter of the hollow frustum reduced during the welding process, there will be an explosion sound of "pop, pop, pop, pop", that is, high-frequency noise. With the appearance of this sound, there will be adverse consequences such as fracture, porosity, and welding slag in the weld. Therefore, on the basis of reducing the diameter of the hollow frustum of the protective sleeve, noise-reducing round holes are provided on the protective sleeve, and the size and position of the noise-reducing round holes punched on the protective sleeve are optimized and calculated according to the design requirements of the total sound power of the jet noise, and then the punching is accurately implemented, so that the total sound power of the jet noise accurately meets the design requirements, reducing the speed and pressure of the argon jet at the air outlet of the protective sleeve, eliminating the discrete noise caused by the huge instantaneous pressure change in the jet mixing zone, effectively eliminating the high-frequency noise during the welding process, and at the same time, the argon gas ejected from the noise-reducing round holes and the argon gas ejected from the air outlet of the protective sleeve can better play the role of preventing oxidation at the welding place. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the present invention.

[0026] Figure 2 is a schematic diagram of the present invention for welding a small-angle slit weldment.

[0027] Figure 3 is a schematic diagram of the dimensional parameters of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be further described below in conjunction with the drawings and embodiments.

[0029] As Figure 1 and Figure 2 shown, a welding gun head suitable for a small-angle slit of the present invention includes a gas channel 1, round holes 3, a contact tip 4, and a protective sleeve 5; the contact tip 4 and the protective sleeve 5 are fixed by a connecting piece, and a gas channel 1 is provided between the side of the contact tip 4 and the protective sleeve 5 for flowing argon gas; the inner diameter at the air outlet of the protective sleeve 5 is 9-11 mm, the outer diameter is 12-14 mm, and both the inner and outer diameters are reduced by more than 2 mm compared with the existing common sizes; a plurality of round holes 3 evenly distributed in the circumferential direction are opened at the cross-section of the protective sleeve near the air outlet of the protective sleeve; the welding wire 2 is installed on the contact tip and extends out of the protective sleeve; on the premise of ensuring that the length of the welding wire 2 extending out of the contact tip is between 10 and 15 mm, by reducing the inner and outer diameters at the air outlet of the protective sleeve, when there is a small-angle slit 7 between two weldments 6, the present invention can penetrate deeper into the slit, so that the welding wire can be normally arc-started and high-quality welding can be completed on the premise of ensuring a reasonable wire extension length.

[0030] However, after the inner diameter at the air outlet of the protective sleeve is reduced, if no round holes are opened on the protective sleeve 5, during the process of argon passing through the gas channel 1 between the protective sleeve and the conductive nozzle 4, due to the sharp reduction in the cross-sectional area of the gas channel, the argon is ejected at an accelerated speed, forming a high-speed jet flow and generating high-frequency noise. For this reason, the present invention opens a plurality of round holes 3 evenly distributed in the circumferential direction at the cross-section of the protective sleeve close to the air outlet of the protective sleeve, thereby controlling the total sound power of the jet flow noise at the air outlet of the protective sleeve and avoiding excessive welding noise during the production process.

[0031] As Figure 3 shown below, the following describes how to open round holes to accurately reduce the total sound power of the jet flow noise to meet the design requirements, so that the welding noise meets the requirements. The design parameters of the round holes are: the number of round holes n, the diameter of the round holes, and the distance between the cross-section where the centers of the round holes are located and the air outlet of the protective sleeve. The main design idea is: according to the total sound power P T of the jet flow noise to be achieved, the jet flow velocity U1 at the air outlet of the protective sleeve that should be achieved is obtained, and then according to the relationship between U1 and the structural parameters of the conductive nozzle 4, the structural parameters of the protective sleeve 5, and the design parameters of the round holes, the number of round holes n, the diameter of the round holes, and the distance between the cross-section where the centers of the round holes are located and the air outlet of the protective sleeve are selected to make the jet flow velocity at the air outlet of the protective sleeve meet the design requirements, so that the total sound power P T of the jet flow noise meets the design requirements. The specific process is as follows:

[0032] The total sound power P T of the jet flow noise is calculated as follows:

[0033]

[0034] Among them, U1 is the jet flow velocity at the air outlet of the protective sleeve, ρ0 is the ambient air density, and ρ s is the instantaneous air density in the hollow frustum region of the protective sleeve (since the flow rate Q before the air flow passes through the round holes on the protective sleeve, the flow rate Q n flowing out of each round hole, and the flow rate Q1 after the air flow passes through the round holes on the protective sleeve remain unchanged, ρ s can be considered a fixed value), D1 is the inner diameter at the air outlet of the protective sleeve (the protective sleeve is composed of an integrally formed cylinder and a hollow frustum. When designing the dimensions of the protective sleeve, the height H of the hollow frustum and the inner diameter D2 of the cylinder of the protective sleeve are kept unchanged, and D1 is determined according to the slit angle), K L is an experimental constant, here taking 3×10 -5 , and c0 is the speed of sound. It can be seen that D1, c0, ρ0, K L , ρ s remain unchanged, and the total sound power is only related to U1 and has an 8th power relationship with U1. Therefore, the present invention mainly considers the influence of the jet flow velocity at the air outlet of the protective sleeve on the noise.

[0035] After the air flow passes through the cross-section where the centers of the circular holes on the protective sleeve are located, part of the gas is discharged to the atmospheric environment through the circular holes, and the flow rate decreases. The jet velocity U1 at the air outlet of the protective sleeve decreases. Let the flow rate of the air flow before passing through the circular holes on the protective sleeve be Q, and the flow rate after passing through the circular holes on the protective sleeve be Q1. According to the law of conservation of mass, the flow rate Q of the air flow before passing through the circular holes on the protective sleeve is equal to the sum of the flow rates Q n flowing out of each circular hole and the flow rate Q1 flowing out of the protective sleeve, that is:

[0036] Q = Q1 + Q n

[0037] Then there is:

[0038] Q1 = Q - Q n = Q - n * r 2 * π * U x (1)

[0039] where n is the number of circular holes and r is the radius of the circular hole;

[0040] Since Q is known, according to Q, the cross-sectional area of the cross-section where the centers of the circular holes on the protective sleeve are located, and the cross-sectional area of the cross-section at the position on the nozzle 4 aligned with the centers of the circular holes, the air flow velocity U at the circular holes is solved x as follows:

[0041]

[0042] where, as Figure 3 shown, the cross-sectional diameter D at a distance x from the air outlet of the protective sleeve of the protective sleeve x = [(D2 - D1)·x] / H + D1, where x is the distance between the cross-section where the centers of the circular holes are located and the air outlet of the protective sleeve, D2 is the inner diameter of the cylinder of the protective sleeve, and H is the height of the hollow frustum of the protective sleeve; the cross-sectional diameter d at a distance x from the air outlet of the protective sleeve of the nozzle x = [(d2 - d1)·x] / h + d1, where h is the height of the frustum part of the nozzle (the nozzle is composed of a frustum part and a cylindrical part formed integrally), d1 is the cross-sectional diameter at the position where the nozzle is aligned with the air outlet of the protective sleeve, and d2 is the diameter of the cylindrical part of the nozzle.

[0043] By combining Equation (1) and Equation (2), the flow rate Q1 after the air flow passes through the circular holes on the protective sleeve is obtained, and combined with the cross-sectional area at the air outlet of the protective sleeve and the cross-sectional area at the position where the nozzle 4 is aligned with the air outlet of the protective sleeve, the jet velocity U1 at the air outlet of the protective sleeve is solved as follows:

[0044]

[0045] It can be seen that if the total sound power P of the jet noise in the known design range T , after obtaining the design range of U1, the formulas (1), (2), (3), and the relationship D can be combinedx = [(D2 - D1)·x] / H + D1 and the relational expression d x = [(d2 - d1)·x] / h + d1. By setting the number of circular holes n, the radius r of the circular holes, and the distance x between the cross-section where the center of each circular hole is located and the air outlet of the protective sleeve, the value of U1 can meet the requirements of the specific design range, so that the total sound power P of the jet noise T meets the design range requirements. Therefore, the present invention actually establishes the corresponding relationship between the total sound power P of the jet noise T and the number of circular holes n, the radius r of the circular holes, and the distance x between the cross-section where the center of each circular hole is located and the air outlet of the protective sleeve. Thus, according to the noise reduction requirements, the number of circular holes n, the radius r of the circular holes, and the distance x between the cross-section where the center of each circular hole is located and the air outlet of the protective sleeve can be directly designed through this corresponding relationship, providing a solution for opening circular holes to reduce the welding noise of the welding gun head during the production process, and providing a theoretical basis for the position and size of the circular holes required for the accurate control of the welding noise of the welding gun head. When designing, attention should be paid to the appropriate values of the number of circular holes n and the radius r of the circular holes. If the number of circular holes n and the radius r of the circular holes are too large, the jet velocity U1 at the air outlet of the protective sleeve will be too small, and thus the role of argon in preventing oxidation during the welding process cannot be achieved. If the number of circular holes n and the radius r of the circular holes are too small, the purpose of reducing the jet velocity U1 at the air outlet of the protective sleeve to the design range cannot be achieved.

[0046] As a preferred embodiment, since the instantaneous air density ρ in the hollow frustum region of the protective sleeve s is relatively cumbersome to detect, and it is often impossible to ensure a very high accuracy during detection. Therefore, directly calculating U1 through the relational expression between U1 and the total sound power P of the jet noise T is not the best way. The present invention avoids this method, measures the total sound power P T ' of the jet noise of the existing welding gun head model (any existing size of the welding gun head model can be selected), and combines the jet velocity U1' at the air outlet of the protective sleeve of the existing welding gun head model (which can be calculated by replacing Q1 in formula (3) with the flow rate at the air outlet of the protective sleeve of the existing welding gun head model) and the inner diameter D1' at the air outlet of the protective sleeve of the existing welding gun head model. According to the expression of the ratio of the total sound power P of the jet noise of the present invention T and P T ', calculate the design range of the jet velocity U1 at the air outlet of the protective sleeve that should be achieved when meeting the design range of the total sound power P of the jet noise; the expression of the ratio of the total sound power P of the jet noise T and P T ' is as follows: T The expression of the ratio of P and P' is as follows:

[0047]

[0048] After obtaining the design range of the jet velocity U1 at the air outlet of the protective cover, by setting the number of round holes n, the radius r of the round holes, and the distance x between the cross-section where the centers of the round holes are located and the air outlet of the protective cover, the value of U1 can be made to meet the requirements of the specific design range, and thus the total sound power P of the jet noise can be achieved. T Meet the design range requirements, thereby controlling the welding noise and making the welding noise meet the requirements.

Claims

1. A welding gun head applicable to small-angle narrow slits, comprising a gas channel, a round hole, a contact tip and a protective sleeve; the contact tip and the protective sleeve are fixed by a connecting piece, and a gas channel is arranged between the side surface of the contact tip and the protective sleeve; it is characterized in that: The inner diameter at the air outlet of the protective sleeve is 9 - 11 mm, and the outer diameter is 12 - 14 mm; a plurality of circular holes evenly distributed in the circumferential direction are provided at the cross-section of the protective sleeve near the air outlet of the protective sleeve; The specific process of reducing the total sound power of the jet noise by opening the circular holes to meet the design requirements is as follows: Total sound power P of jet noise T The calculation is as follows: Among them, U1 is the jet velocity at the air outlet of the protective cover, ρ0 is the ambient air density, and ρ s is the instantaneous air density within the hollow frustum region of the protective cover, D1 is the inner diameter at the air outlet of the protective cover, and K L is an experimental constant, taking 3×10 -5 , and c0 is the speed of sound; Let the flow rate of the air before passing through the round holes on the protective sleeve be Q, the flow rate of the air after passing through the round holes on the protective sleeve be Q1, and the sum of the flow rates of each round hole be Q n , then there is: Q = Q1 + Q n Obtained: Q1 = Q - Q n = Q - n * r 2 * π * U x (1) Where n is the number of circular holes and r is the radius of the circular hole; Since Q is known, the air flow velocity U at the round holes is solved according to Q, the cross-sectional area where the centers of the round holes on the protective sleeve are located, and the cross-sectional area at the positions on the conductive nozzles aligned with the centers of the round holes x as follows: Among them, the cross-sectional diameter D at the position x from the air outlet of the protective sleeve x = [(D2 - D1)·x] / H + D1, where x is the distance between the cross-section where the centers of the round holes are located and the air outlet of the protective sleeve, D2 is the inner diameter of the cylinder of the protective sleeve, and H is the height of the hollow frustum of the protective sleeve; the cross-sectional diameter d at the position x from the air outlet of the protective sleeve of the conductive nozzle x = [(d2 - d1)·x] / h + d1, where h is the height of the frustum part of the conductive nozzle, d1 is the cross-sectional diameter at the position where the conductive nozzle is aligned with the air outlet of the protective sleeve, and d2 is the diameter of the cylindrical part of the conductive nozzle; Combining Equation (1) and Equation (2), the flow rate Q1 after the air flow passes through the circular holes on the protective sleeve is obtained, and in combination with the cross-sectional area at the air outlet of the protective sleeve and the cross-sectional area at the alignment position of the conductive nozzle and the air outlet of the protective sleeve, the jet velocity U1 at the air outlet of the protective sleeve is solved as follows: Based on the total sound power P of the jet noise within the known design range T , after obtaining the U1 design range, combining formulas (1), (2), (3), and the relationship D x = [(D2 - D1)·x] / H + D1 and the relationship d x = [(d2 - d1)·x] / h + d1, by setting the number of circular holes n, the radius r of the circular holes, and the distance x between the cross-section where the centers of each circular hole are located and the air outlet of the protective sleeve, the value of U1 is made to meet the requirements of the specific design range, so that the total sound power P of the jet noise T meets the requirements of the design range.

2. The welding gun head applicable to small-angle narrow slits according to claim 1, wherein: Measure the total sound power P of the jet noise of the existing welding gun head model, and combine the jet velocity U1' at the air outlet of the protective sleeve of the existing welding gun head model and the inner diameter D1' at the air outlet of the protective sleeve of the existing welding gun head model. According to the expression of the ratio of P T ' and P T , calculate the jet velocity U1 design range at the air outlet of the protective sleeve that should be achieved when meeting the design range of the total sound power P of the jet noise; the expression of the ratio of the total sound power P of the jet noise T and P T ' is as follows: T and P T ' is as follows:

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