Method for manufacturing welded shell of coal mining machine

Abstract

The invention discloses a method for manufacturing a welded shell of a coal mining machine, which comprises the following steps of: blanking a steel plate, welding and performing a first water pressure sealing test, the steps sequentially carried out after the step of the first water pressure sealing performance test comprise semi-finish machining, first drilling, first inspection and repair welding, second water pressure sealing performance test, finish machining, second drilling and third water pressure sealing performance test, and during semi-finish machining, all surfaces with roughness requirements are machined till the allowance of 1 mm or below is reserved on a single side; during first-time drilling, screw holes with the position degree requirement being smaller than 0.5 mm are shrunk, screw holes with the position degree requirement being larger than or equal to 0.5 mm are drilled and tapped in place, and holes which are communicated with weld joints and have no position degree requirement are drilled and tapped in place. The method solves the problem of high repair difficulty caused by exposure of partial defects of the welded shell of the coal mining machine during finish machining.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a coal mining machine shell, in particular to a method for manufacturing a welded coal mining machine shell. Background Art

[0002] During the coal mining process, the gears of the coal mining machine transmission system rub against each other through contact, which will wear the surface of the gears and generate a lot of heat. In order to alleviate the wear on the gear surface, reduce friction and increase heat dissipation, lubricating oil needs to be added to the coal mining machine transmission system, especially the reduction cavity connected to the motor in the left and right traction box housings and the travel cavity connected to the travel box housing. Almost every welded traction box housing has sealing requirements for these two cavities.

[0003] The production process of the prior art mainly involves the first water pressure sealing test after welding, followed by rough machining, inspection and repair welding, fine machining, drilling, and then the second water pressure sealing test. In the actual production process, it is impossible for the weld to not have pores, and some pores are difficult to find in the weld. When the second water pressure sealing test is performed after the shell is finely machined, the sealing pressure cannot be maintained, and the weld and the defects in the weld (such as pores) are connected, resulting in water leakage in the weld, resulting in failure of the water pressure sealing test. The final product needs to be repaired, but repairing these defects at this time will affect the surface that has been finely machined. Summary of the invention

[0004] In view of the above-mentioned defects in the prior art, the task of the present invention is to provide a method for manufacturing a welded shell of a coal mining machine, aiming to solve the problem that weld quality problems cannot be discovered in time, resulting in failure of the final water pressure sealing test and difficulty in product repair.

[0005] The technical solution of the present invention is as follows: A method for manufacturing a welded shell of a coal mining machine, comprising the steps of cutting steel plates, welding and a first water pressure sealing test, wherein the steps performed in sequence after the first water pressure sealing test step include: semi-finishing, first drilling, first inspection and repair welding, a second water pressure sealing test, finishing, second drilling and a third water pressure sealing test, wherein during the semi-finishing, each surface with a roughness requirement is processed to leave a single-side margin of less than 1 mm; during the first drilling, the screw holes with a positioning requirement of <0.5 mm are reduced, the screw holes with a positioning requirement of ≥0.5 mm are drilled and tapped into place, and the holes that pass through the weld and have no positioning requirement are drilled and tapped into place.

[0006] Furthermore, during the semi-finishing, the functional features that do not have relative matching requirements are processed in place.

[0007] Furthermore, the functional features include an oil drain hole, an oil filling hole, and an oil mark hole.

[0008] Furthermore, during the semi-finishing, the hole diameter tolerance of the hole involved in the second water pressure sealing test and the shaft diameter tolerance of the water pressure sealing tool are matched.

[0009] Furthermore, the semi-finishing includes shrinking the mounting screw holes around the tooling plugging holes of the second water pressure sealing test.

[0010] Furthermore, the semi-finishing includes chamfering the hole.

[0011] Furthermore, a second repair welding is added between the second water pressure sealing test and the finishing step, and the second repair welding is for repairing the defects exposed by the second water pressure sealing test.

[0012] The advantages of the present invention compared with the prior art are:

[0013] The rough machining after the first water pressure sealing test was changed to semi-finishing, which reduced the machining margin of the process within a controllable range, further exposed the defects of the weld, and avoided the defects exposed after finishing and causing rework. The dimensional tolerance of the guide hole involved in the second water pressure sealing test was further controlled during semi-finishing to prepare for the test.

[0014] Conduct a second hydraulic sealing test before finishing, and conduct the first inspection and repair welding before the second hydraulic sealing test, so that defects that are not easy to find in small corners through conventional inspection methods can be more intuitively and effectively discovered and handled in time, and further repair defects through the second repair welding to prepare for finishing. Repair the defects found before the finishing process, reduce the repair work after finishing, and reduce the impact of thermal deformation of repair welding on the surface after finishing. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with the embodiments, but are not intended to limit the present invention.

[0016] The present invention relates to a method for manufacturing a welded shell of a coal mining machine, and its complete process route comprises steel plate cutting, steel plate welding groove pre-processing, assembly, first heat treatment, welding, second heat treatment, inspection, shot blasting, first water pressure sealing test, marking, semi-finishing, first drilling, first inspection and repair welding, second water pressure sealing test, second repair welding, finishing, second inspection, second drilling, clamp processing, third water pressure sealing test, finished product inspection and warehousing.

[0017] Compared with the previous process, the main process is to change the rough machining to semi-finishing. The requirement of semi-finishing is that each surface with roughness requirements should be machined to leave a single-side margin of 1mm. The aperture tolerance of the holes involved in the second water pressure sealing test must be matched with the shaft diameter tolerance of the water pressure sealing tool, such as the matching tolerance H7 / f8 (for the installation of water pressure tooling with sealing rings in the water pressure sealing test process), and each hole is chamfered. The holes blocked by the tooling for the water pressure sealing test are generally designed with installation screw holes. In this process, the installation screw holes can be reduced by 4mm for processing (for example, M12 screw holes are drilled to M8) in order to facilitate the installation of the sealing tooling in the second water pressure sealing test process. In some embodiments, these installation screw holes can also be not processed in this process, and they can be processed together in the finishing process. In the second water pressure sealing test process, the sealing tooling is installed by spot welding of the reinforced plate. Both solutions have been implemented and verified to be feasible. For most of the welds processed in this process, most of the welds that need to be processed have been removed, and only the remaining 1mm depth has not been processed. Most of the weld defects can be fully exposed after executing this process, and these exposed defects can be repaired in the first inspection and repair welding process.

[0018] The main difference between the semi-finishing process and the previous rough machining process lies in the processing content. As the requirements for the hole size are increased, the shape and position accuracy of the hole relative to the previous rough machining process are also improved. In this way, some functional features that do not require high position accuracy and have no relative matching requirements for other holes can be processed in place in advance, such as oil drain holes, oil filling holes, oil mark holes, etc., which reduces the content of subsequent finishing, shortens the subsequent finishing cycle, and further exposes defects in advance.

[0019] During the first drilling, screw holes with a position requirement of <0.5mm are reduced, for example, the screw holes of M12 in the drawing are drilled and tapped into M8 in this process; screw holes with a position requirement of ≥0.5mm are drilled and tapped in place, and holes that penetrate the weld and have no position requirement are drilled and tapped in place. The first drilling can facilitate the installation of the tooling for the first water pressure sealing test. In addition, defects are fully exposed before the finishing process, which makes it easier for defects to be discovered in time and the product to be repaired in time.

[0020] The first inspection and repair welding is to check and find out the defects exposed by the previous process, and perform corresponding repair welding and rework, such as carbon arc stripping, grinding, uniform preheating, repair welding, boring and drilling.

[0021] During the second water pressure sealing test, first clean the parts, and then use the designed tooling to perform a water pressure sealing test on the cavity. After this process is executed, the defects that have been discovered and the defects that have been exposed but not discovered can be intuitively found. In this process, the cavity is filled with water and pressurized to 0.5MPa. After maintaining the pressure for a specified time (generally not less than 30 minutes), if the pressure drops, check whether there is a leak. The location where there is a leak is the location where the defect exists. Some defects that are not easy to find in small corners by conventional inspection methods can be discovered more intuitively.

[0022] The second repair welding is to carry out corresponding repairs on the defects found in the second water pressure sealing test, such as carbon arc stripping, grinding, uniform preheating and repair welding.

[0023] The process method of the present invention can effectively reduce the situation of product rework after fine processing because defects are exposed in advance through multiple steps in the process.

Claims

1. A method for manufacturing a welded shell of a coal mining machine, comprising the steps of cutting steel plates, welding and a first water pressure sealing test, characterized in that: The steps performed in sequence after the first water pressure sealing test step include: semi-finishing, first drilling, first inspection and repair welding, second water pressure sealing test, finishing, second drilling and third water pressure sealing test. During the semi-finishing, each surface with roughness requirements is processed to leave a single-side margin of less than 1mm; during the first drilling, the screw holes with a positioning requirement of <0.5mm are reduced, the screw holes with a positioning requirement of ≥0.5mm are drilled and tapped into place, and the holes that pass through the weld and have no positioning requirements are drilled and tapped into place.

2. The method for manufacturing a coal mining machine welded shell according to claim 1, characterized in that: The semi-finishing process is to process the functional features that do not have relative matching requirements in place.

3. The method for manufacturing a coal mining machine welded shell according to claim 1, characterized in that: The functional features include an oil drain hole, an oil filling hole, and an oil mark hole.

4. The method for manufacturing a coal mining machine welded shell according to claim 1, characterized in that: During the semi-finishing, the hole diameter tolerance of the hole involved in the second water pressure sealing test and the shaft diameter tolerance of the water pressure sealing tool are matched.

5. The method for manufacturing a coal mining machine welded shell according to claim 1, characterized in that: The semi-finishing process includes shrinking the mounting screw holes around the tooling plugging holes for the second water pressure sealing test.

6. The method for manufacturing a coal mining machine welded shell according to claim 1, characterized in that: The semi-finishing process includes chamfering the hole.

7. The method for manufacturing a coal mining machine welded shell according to claim 1, characterized in that: A second repair welding is added between the second water pressure sealing test and the finishing step, and the second repair welding is used to repair the defects exposed by the second water pressure sealing test.