A solenoid valve sleeve welding structure and high-frequency brazing method

Abstract

The present invention discloses a solenoid valve sleeve welding structure, comprising an upper valve sleeve of industrial pure iron DT4C, a lower valve sleeve of industrial pure iron DT4C and a magnetic isolation ring of brass H62, wherein an upper frustum with a conical outer circumference and a cylindrical inner hole is provided at the bottom of the upper valve sleeve, a lower groove with a conical outer circumference and a cylindrical inner circumference is provided at the top of the lower valve sleeve, an upper groove with a conical outer circumference and a cylindrical inner circumference is provided at the top of the magnetic isolation ring, and a lower frustum with a conical outer circumference and a cylindrical inner hole is provided at the bottom; the upper frustum is embedded in the upper groove, the inner hole in the upper frustum is interference fit with the inner circumference of the upper groove, and a brazing seam is left between the outer circumference of the upper frustum and the outer circumference of the upper groove; the lower frustum is embedded in the lower groove, the inner hole in the lower frustum is interference fit with the inner circumference of the lower groove, and a brazing seam is left between the outer circumference of the lower frustum and the outer circumference of the lower groove. The invention also discloses a high-frequency brazing method for the electromagnetic valve sleeve welding structure.

Description

Technical Field

[0001] The present invention relates to the technical field of solenoid valves, and in particular to a solenoid valve sleeve welding structure and a high-frequency brazing method. Background Art

[0002] The valve sleeve of the solenoid valve must have a magnetic isolation structure, such as Figure 1 As shown, the current valve sleeve assembly consists of an upper sleeve 1 made of industrial pure iron DT4C, a lower sleeve 2 made of industrial pure iron DT4C, and a magnetic isolation ring 3 made of brass H62, which is welded together. The magnetic isolation ring 3 is located between the upper and lower sleeves 1 and 2. Based on the welding properties of the above two materials and the dimensional accuracy requirements of the finished valve sleeve assembly, brazing is used to ensure the accuracy. The finished valve sleeve assembly has an inner diameter of 15mm and an outer diameter of 19mm. The structure must meet the following design requirements:

[0003] (1) The tensile strength of the welded joint at room temperature is ≥180MPa.

[0004] (2) During the test of 0.2MPa hydraulic oil pressure, no leakage shall occur at the welding part.

[0005] The main factor affecting the welding quality of industrial pure iron DT4C and brass H62 is the significant difference in their melting point, thermal conductivity, and linear expansion coefficient. This can easily lead to significant welding stress and deformation, as well as problems such as porosity and slag inclusions. Currently, the main welding methods for DT4C and H62 materials include fusion welding, friction welding, and brazing, but these methods struggle to address these technical issues. Summary of the Invention

[0006] One of the objectives of the present invention is to provide a solenoid valve sleeve welding structure in view of the above-mentioned deficiencies existing in the valve sleeve component of the solenoid valve, so as to solve the problems raised in the above-mentioned background technology.

[0007] A second object of the present invention is to provide a high-frequency brazing method for a solenoid valve sleeve in order to address the above-mentioned deficiencies of the valve sleeve component of the solenoid valve.

[0008] In order to achieve the above-mentioned purpose of the invention, the present invention provides a solenoid valve sleeve welding structure, comprising an upper valve sleeve made of industrial pure iron DT4C, a lower valve sleeve made of industrial pure iron DT4C and a magnetic isolation ring made of brass H62, characterized in that an upper frustum with a conical outer surface and a cylindrical inner hole is provided at the bottom of the upper valve sleeve, a lower groove with a conical outer surface and a cylindrical inner surface is provided at the top of the lower valve sleeve, and a lower groove with a conical outer surface and a cylindrical inner surface is provided at the top of the magnetic isolation ring. The upper groove of the cylinder is provided with a lower frustum whose outer circumference is a conical surface and the inner hole is a cylindrical surface at the bottom of the magnetic isolation ring; the upper frustum is embedded in the upper groove, the inner hole in the upper frustum is interference fit with the inner circumference of the upper groove, and a brazing seam is left between the outer circumference of the upper frustum and the outer circumference of the upper groove; the lower frustum is embedded in the lower groove, the inner hole in the lower frustum is interference fit with the inner circumference of the lower groove, and a brazing seam is left between the outer circumference of the lower frustum and the outer circumference of the lower groove.

[0009] In a preferred embodiment of the present invention, the outer circumferential surface of the upper frustum is connected to the edge of the inner hole via a first annular plane, which constitutes the lowest point of the upper frustum; the outer circumferential surface and the inner circumferential surface of the upper groove are connected via a second annular plane, which constitutes the deepest point of the upper groove; the outer circumferential surface of the lower frustum is connected to the edge of the inner hole via a third annular plane, which constitutes the lowest point of the lower frustum; the outer circumferential surface and the inner circumferential surface of the lower groove are connected via a fourth annular plane, which constitutes the deepest point of the lower groove.

[0010] In a preferred embodiment of the present invention, a brazing seam is left between the first ring plane and the second ring plane, and a brazing seam is left between the third ring plane and the fourth ring plane.

[0011] In a preferred embodiment of the present invention, the maximum diameter of the outer circumference of the upper groove is greater than the maximum diameter of the outer circumference of the upper frustum, and the maximum diameter of the outer circumference of the lower groove is greater than the maximum diameter of the outer circumference of the lower frustum.

[0012] In a preferred embodiment of the present invention, the width of the brazing seam is between 0.05 mm and 0.15 mm.

[0013] In a preferred embodiment of the present invention, the outer circumferential surface of the upper frustum, the outer circumferential surface of the upper groove, the outer circumferential surface of the lower frustum, and the outer circumferential surface of the lower groove form an angle of 45° with the axis of the valve sleeve component.

[0014] The high-frequency brazing method of the electromagnetic valve sleeve of the present invention comprises the following steps:

[0015] Step 1: Fill the soldering seam with solder paste;

[0016] Step 2: Place the assembled valve sleeve component vertically and steadily into the center area of ​​the high-frequency brazing induction coil for welding; brazing process parameters: first section, current, 65A, time 6s; second section, current 55A, time 3s; third section, current 50A, time 9s; total welding time is 18s;

[0017] Step 3: After brazing is completed, take out the welded valve sleeve components and place them at room temperature to cool naturally.

[0018] In a preferred embodiment of the present invention, the solder paste is Ag45Cu27Zn25Sn3.

[0019] Due to the adoption of the above technical solution, the present invention has the following advantages compared with the prior art:

[0020] 1. The valve sleeve component of the present invention utilizes a compensation structure design to compensate for weld variations caused by the large difference in expansion coefficients of the two metals, thereby ensuring uniform weld gaps and improving weld strength and density.

[0021] 2. The amount of solder required for the weld is theoretically calculated, allowing for quantitative control of the amount of brazing material used. Furthermore, during the welding process, the solder paste flows into the gap due to gravity and capillary action, thereby filling the weld seam completely. This prevents the solder paste from overflowing from the weld seam after heating. The sleeve-welded structure of the valve sleeve assembly of the present invention acts as a "baffle."

[0022] The present invention can save the amount of solder paste used, reduce production costs, avoid problems such as pores and slag inclusions, improve the strength and density of the weld, and achieve good welding quality consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the existing valve sleeve component.

[0024] Figure 2 It is a schematic diagram of the welding structure of the solenoid valve sleeve of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and examples, but the present invention is not limited to the scope of the described embodiments.

[0026] See also Figure 2 The solenoid valve sleeve welding structure shown in the figure includes an upper valve sleeve 10 made of industrial pure iron DT4C, a lower valve sleeve 20 made of industrial pure iron DT4C, and a magnetic isolation ring 30 made of brass H62.

[0027] An upper frustum 11 having a conical outer surface 11a and a cylindrical inner hole 11b is provided at the bottom of the upper valve sleeve 10. The outer surface 11a of the upper frustum 11 and the edge of the inner hole 11b are connected by a first annular plane 11c, which constitutes the lowest point of the upper frustum 11.

[0028] A lower groove 21 with a conical outer surface 21a and a cylindrical inner surface 21b is provided at the top of the lower valve sleeve 20. The outer surface 21a and the inner surface 21b of the lower groove 21 are connected by a fourth annular plane 21c, which constitutes the deepest part of the lower groove 21.

[0029] An upper groove 31 with a conical outer surface 31a and a cylindrical inner surface 31b is provided at the top of the magnetic isolation ring 30. The outer surface 31a and the inner surface 31b of the upper groove 31 are connected by a second ring plane 31c, and the second ring plane 31c constitutes the deepest part of the upper groove 31; a lower cone 32 with a conical outer surface 32a and a cylindrical inner hole 32b is provided at the bottom of the magnetic isolation ring 30. The outer surface 32a of the lower cone 32 and the edge of the inner hole 32b are connected by a third ring plane 32c, and the third ring plane 32c constitutes the lowest point of the lower cone 32.

[0030] The outer surface 11a of the upper cone 11, the outer surface 31a of the upper groove 31, the outer surface 32a of the lower cone 32, and the outer surface 21a of the lower groove 21 form a 45° angle with the axis of the valve sleeve. This creates a 45° brazing seam, which facilitates capillary flow of the brazing paste during the welding process. The angular tolerances of the outer surface 11a of the upper cone 11, the outer surface 31a of the upper groove 31, the outer surface 32a of the lower cone 32, and the outer surface 21a of the lower groove 21 control the brazing seam width at the welded portion of the finished valve sleeve (circumferential diameter within the range of 15 mm to 19 mm). The maximum diameter of the outer surface 11a of the upper groove 31 is larger than that of the upper cone 11, and the maximum diameter of the outer surface 21a of the lower groove 21 is larger than that of the outer surface 32a of the lower cone 32. In this way, after the upper valve sleeve 10 and the magnetic isolation ring 30 are assembled, and after the magnetic isolation ring 30 and the lower valve sleeve 20 are assembled, grooves C1 and C2 can be formed on the upper edge of the assembled brazing seam, which can be filled with brazing paste before welding. During the welding process, the brazing paste is heated and, under the action of gravity, the brazing paste can flow into the brazing seam, thereby filling the brazing seam and ensuring the strength and density of the brazing seam between the upper valve sleeve 10 and the magnetic isolation ring 30 and the brazing seam between the magnetic isolation ring 30 and the lower valve sleeve 20.

[0031] The height d1 of the upper cone 11 is less than the depth d2 of the upper groove 31, leaving a brazing seam A1 between the two. The height d4 of the lower cone 32 is less than the depth d4 of the lower groove 21, leaving a brazing seam A2 between the two. The brazing seam A1 is connected to the brazing seam A2 and the groove C1.

[0032] Before brazing, the upper valve sleeve 10, the magnetic isolation ring 30 and the lower valve sleeve 20 are assembled together by means of sleeve connection, wherein the upper frustum 11 is embedded in the upper groove 31, and the inner hole 11b of the upper frustum 11 is interference fit with the inner circumference 31b of the upper groove 31, and the interference is 0 to 0.02mm, so as to ensure the coaxiality between the upper valve sleeve 10 and the magnetic isolation ring 30; a brazing seam A2 is left between the outer circumference 11a of the upper frustum 11 and the outer circumference 31a of the upper groove 31; the lower frustum 32 is embedded in the lower groove 21, and the inner hole 32b of the lower frustum 32 is interference fit with the inner circumference 21b of the lower groove 21, and the interference is 0 to 0.02mm, so as to ensure the coaxiality between the magnetic isolation ring 30 and the lower valve sleeve 20; a brazing seam B2 is left between the outer circumference 32a of the lower frustum 32 and the outer circumference 21a of the lower groove 21. The brazing seam B1 penetrates the brazing seam B2 and the groove C2.

[0033] The width of the brazing seams A1, A2, B1, and B2 is between 0.05 mm and 0.15 mm. This can better control the width of the brazing seams on the one hand, and on the other hand, due to the large difference in the expansion coefficients of the two metals, the expansion during the welding heating process causes the width of the brazing seams to change, which can better compensate for the brazing seams and make the brazing seam gaps uniform. In addition, during the welding process, the brazing paste will rely on gravity and capillary action to flow into the brazing seams, thereby filling the brazing seams and allowing the brazing seams to be fully filled with brazing material. In addition, the welding structure adopted by the present invention can act as a "baffle" to prevent the brazing paste in the brazing seams from overflowing after being heated. The above three aspects can all improve the strength and density of the brazing seams.

[0034] Since the chemical composition and thermal expansion coefficient of industrial pure iron DT4C and brass H62 are very different, the brazing paste used in the present invention is Ag45Cu27Zn25Sn3. This brazing paste has good wettability and capillary fluidity on the weld surface of industrial pure iron DTC4 and brass H62, which can improve the welding quality.

[0035] The present invention can control the brazing seam width of the finished product welding of the valve sleeve component to be between 0.05mm and 0.15mm by involving the welding structure of the valve sleeve component.

[0036] The high-frequency brazing method of the electromagnetic valve sleeve of the present invention comprises the following steps:

[0037] 1. Cleaning parts: Use an ultrasonic cleaning machine and hydrocarbon as a cleaning agent to clean impurities and oil stains on the surface of the upper valve sleeve 10, the magnetic isolation ring 30, and the lower valve sleeve 20. The brazing paste (Ag45Cu27Zn25Sn3) used in this method contains a flux that can remove oxides on the surface of the parts, so there is no need to use a flux to clean the parts.

[0038] 2. Apply solder paste: The amount of solder paste required for the brazing gap is 0.5g, and the solder is evenly applied on the welding surfaces of the upper valve sleeve 10, the magnetic isolation ring 30, and the lower valve sleeve 20.

[0039] 3. Component Assembly: In this structure, the upper valve sleeve 10, magnetic isolation ring 30, and lower valve sleeve 20 are assembled using an interference fit with an interference fit of 0 to 0.02 mm. Use a press to ensure that the upper valve sleeve 10, magnetic isolation ring 30, and lower valve sleeve 20 are fully press-fitted into place.

[0040] 4. Apply solder paste: After assembly, fill the grooves C1 and C2 with solder paste.

[0041] 5. Component brazing: Place the assembled components vertically and steadily in the center area of ​​the high-frequency brazing induction coil. The induction coil should cover the weld area between part 1 and part 2, and between part 2 and part 3. Start the high-frequency brazing equipment. The process parameters are: first section, current, 65A, time 6S; second section, current 55A, time 3S; second section, current 50A, time 9S; the total welding time is 18S.

[0042] 6. Cooling and taking out of the furnace: After brazing is completed, turn off the brazing machine, take out the welded workpiece, and place it at room temperature to cool naturally.

Claims

1. A solenoid valve sleeve welding structure, comprising an upper valve sleeve made of industrial pure iron DT4C, a lower valve sleeve made of industrial pure iron DT4C, and a magnetic isolation ring made of brass H62, characterized in that: An upper frustum with a conical outer circumference and a cylindrical inner hole is provided at the bottom of the upper valve sleeve, a lower groove with a conical outer circumference and a cylindrical inner circumference is provided at the top of the lower valve sleeve, an upper groove with a conical outer circumference and a cylindrical inner circumference is provided at the top of the magnetic isolation ring, and a lower frustum with a conical outer circumference and a cylindrical inner hole is provided at the bottom of the magnetic isolation ring; the upper frustum is embedded in the upper groove, the inner hole in the upper frustum is interference fit with the inner circumference of the upper groove, and a brazing seam is left between the outer circumference of the upper frustum and the outer circumference of the upper groove; the lower frustum is embedded in the lower groove, the inner hole in the lower frustum is interference fit with the inner circumference of the lower groove, and a brazing seam is left between the outer circumference of the lower frustum and the circumference of the lower groove; The outer circumference of the upper frustum is connected to the edge of the inner hole via a first annular plane, which constitutes the lowest point of the upper frustum; the outer circumference and the inner circumference of the upper groove are connected via a second annular plane, which constitutes the deepest point of the upper groove; the outer circumference of the lower frustum is connected to the edge of the inner hole via a third annular plane, which constitutes the lowest point of the lower frustum; the outer circumference and the inner circumference of the lower groove are connected via a fourth annular plane, which constitutes the deepest point of the lower groove; A brazing seam is left between the first ring plane and the second ring plane, and a brazing seam is left between the third ring plane and the fourth ring plane.

2. The solenoid valve sleeve welding structure according to claim 1, characterized in that: The maximum diameter of the outer circumference of the upper groove is greater than the maximum diameter of the outer circumference of the upper frustum, and the maximum diameter of the outer circumference of the lower groove is greater than the maximum diameter of the outer circumference of the lower frustum.

3. The solenoid valve sleeve welding structure according to claim 2, characterized in that: The width of the brazing seam is between 0.05 mm and 0.15 mm.

4. The solenoid valve sleeve welding structure according to claim 3, characterized in that: The outer circumferential surface of the upper frustum, the outer circumferential surface of the upper groove, the outer circumferential surface of the lower frustum, the outer circumferential surface of the lower groove and the axis of the valve sleeve component form an angle of 45 degrees.

5. The high-frequency brazing method for the solenoid valve sleeve welding structure according to any one of claims 1 to 4, characterized in that: The steps include: Step 1: Fill the soldering seam with solder paste; Step 2: Place the assembled valve sleeve component vertically and steadily into the center area of ​​the high-frequency brazing induction coil for welding; brazing process parameters: first section, current, 65A, time 6s; second section, current 55A, time 3s; third section, current 50A, time 9s; total welding time is 18s; Step 3: After brazing is completed, take out the welded valve sleeve components and place them at room temperature to cool naturally.

6. The high frequency brazing method according to claim 5, characterized in that: The solder paste is Ag45Cu27Zn25Sn3.

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