A manufacturing method for high-speed laser cladding of oil cylinder inner hole

Abstract

The present invention provides a method for manufacturing a cylinder inner hole by high-speed laser cladding, comprising the following steps: the first part: processing before cladding: the key part is not processing the inner surface of the threaded section, keeping the threaded section consistent with the scraping surface, turning the first chamfer on the left end face of the threaded section to transition to the first step, and then continuing to turn the second chamfer to transition to the scraping surface; the second part: high-speed laser cladding of the inner hole: setting the cladding path to: scraping surface, the second chamfer on the right side of the scraping surface, the first step, the first chamfer, the inner surface of the threaded section, the stop and the chamfer on the right end of the stop to clad one layer; remelting one layer at each chamfer; the third part: finishing after high-speed laser cladding; the fourth part: welding the cylinder bottom. The high-speed laser cladding manufacturing method for the inner hole of the oil cylinder meets the requirements of the inner hole cladding of the oil cylinder, has small deformation and high precision.

Description

Technical Field

[0001] The invention relates to the technical field of high-speed laser cladding and processing methods, and in particular to a high-speed laser cladding manufacturing method for an inner hole of an oil cylinder. Background Art

[0002] The hydraulic support cylinder is a key component of coal mine machinery, and the working medium of the cylinder is emulsion or concentrated liquid. The inner hole of the cylinder is easily corroded due to the fluctuation of the concentration of the emulsion in the mixing water; at the same time, if the surface hardness of the inner hole of the cylinder is low or the bonding force between the surface treatment layer and the substrate is weak, the continuous friction between the seal and the inner hole of the cylinder is also easy to cause the inner hole of the cylinder to wear and fail. Therefore, the corrosion resistance, wear resistance and bonding strength of the inner hole of the cylinder are crucial. At present, the surface treatment processes of the inner hole of the cylinder are mainly electroplating and cladding. Electroplating is a physical bond with relatively weak bonding force. Cladding is a metallurgical bond with good bonding strength. According to relevant literature reports, the cladding process of the inner hole of the cylinder has great advantages.

[0003] There are two ways of cladding process: 1. Using wire cladding technology (such as CMT cladding copper alloy); 2. Using powder laser cladding technology.

[0004] The inner bore CMT cold metal transition cladding copper alloy process has the characteristics of thick cladding layer (2.5-3.5mm), high cost, and low copper alloy hardness (180~230HB). In order to find the processing benchmark for turning the outer circle of the oil cylinder after cladding scraping and rolling, the cylinder mouth needs to be clad 2~4 layers. Then the cylinder barrel is scraped and rolled as a whole, and the scraping and rolling surfaces at both ends of the cylinder barrel are used as the benchmark to turn the outer circle. This copper alloy cladding technology has a large heat input and the cylinder mouth is easy to deform.

[0005] Chinese patent CN113070638A "A processing method for a high corrosion-resistant hydraulic cylinder barrel" discloses a processing technology for surfacing copper alloy in the inner hole. Due to the large difference in composition between copper alloy and substrate, the circumferential seam welding with substrates such as 27SiMn is prone to cracks, which can easily lead to oil cylinder leakage. In order to ensure the quality of circumferential seam welding, a step is reserved at the end of the cylinder barrel before surfacing (a step is bored within a certain range at the end of the cylinder to an inner hole diameter not greater than Φ (d1~0.5) mm), but this processing method is difficult.

[0006] The laser cladding process is divided into powder ordinary laser cladding and powder high-speed laser cladding. For powder ordinary laser cladding, the cladding layer is thicker, the powder utilization rate is low, the processing efficiency is low, and the heat input is large. Therefore, this process has not been widely promoted; the powder high-speed laser cladding process has the advantages of thin cladding layer, high cladding and processing efficiency, small heat input, small cylinder deformation, and small impact on welding quality. It is the current mainstream promotion process method, but there are many problems in applying it to the cladding treatment of the inner hole of the cylinder.

[0007] On the one hand, due to the limitations of the cladding method and equipment, the cladding layer is thin and multi-layer cladding is not possible, resulting in the inability to use the cylinder mouth finishing surface as a reference for turning the cylinder outer circle after cladding scraping and rolling.

[0008] On the other hand, due to the structural limitations of the cladding equipment, it is difficult to clad the step / transition chamfered parts of the cylinder inner hole, especially the sharp corners, which are prone to cladding defects.

[0009] At present, there is no public and mature manufacturing method for the materials, cladding processes and processing technologies for high-speed powder cladding of the inner hole of the cylinder. For example, the application number is CN201410143265.7, and the name of the invention is: In a hydraulic support cylinder in which the inner hole sealing part is processed by laser cladding technology, the laser cladding technology is only used in the sealing part (near the opening end of the cylinder), which has relatively low technical difficulty and does not affect the subsequent cylinder processing.

[0010] In order to solve the above problems, people have been seeking an ideal technical solution. Summary of the invention

[0011] The purpose of the present invention is to address the deficiencies in the prior art and thereby provide a high-speed laser cladding manufacturing method for the inner hole of an oil cylinder which meets the cladding requirements of the inner hole of the oil cylinder, has small deformation and high precision.

[0012] In order to achieve the above object, the technical solution adopted by the present invention is: a high-speed laser cladding manufacturing method for the inner hole of an oil cylinder, comprising the following steps:

[0013] Part 1: Processing before cladding:

[0014] Step 1.1) Use cold drawn tube blanks as the main body of the cylinder barrel, and shot blast to remove the oxide scale;

[0015] Step 1.2) Support the inner holes at both ends of the cylinder, turn the left and right end surfaces of the cylinder, and turn the outer round chamfers of the left and right end surfaces;

[0016] Step 1.3) Weld the cavity joint seat;

[0017] Step 1.4) Fine boring of inner hole;

[0018] Step 1.5) For the inner holes at both ends of the support cylinder, turn the left and right support holes in turn, turn the outer circle clamps at the left and right ends, and further turn the left and right outer circle chamfers;

[0019] Step 1.6) Keep the left inner support stationary, set the right end frame nest center frame, turn the cylinder mouth end stop, turn the right end and left end chamfers of the stop;

[0020] Step 1.7) The inner surface of the thread segment is not processed, and the thread segment is kept consistent with the scraping surface. The first chamfer is turned on the left end face of the thread segment to transition to the first step, and then the second chamfer is turned to transition to the scraping surface;

[0021] Part 2: Inner hole high-speed laser cladding:

[0022] Step 2.1) Clamp the left end of the clamp head and the right end of the rack to ensure that the inner hole radial runout is within the set range, extend the inner hole laser cladding gun head from the cylinder mouth end to the cylinder tail end, take the cylinder tail end as the cladding starting point, and set the cladding path as: scraping surface, the second chamfer on the right side of the scraping surface, the first step, the first chamfer, the inner surface of the threaded section, the stop and the chamfer on the right end of the stop, cladding one layer;

[0023] Step 2.2) Remelt another layer at each chamfer;

[0024] Part 3: High-speed laser cladding and finishing:

[0025] Step 3.1) Scrape and roll, chamfer the outer edges of both ends of the top cylinder, and insert the scraper head from the cylinder mouth to scrape and roll the entire cylinder bore to the set size;

[0026] Step 3.2) Support the scraping surface of the cylinder barrel at the left end, support the inner surface of the threaded section of the cylinder barrel at the right end, machine the left and right two places, machine the outer circle clamps at the right and left ends, then clamp the outer circle of the left end, support the right end of the frame, and start machining the stop and the inner surface of the threaded section from the cylinder mouth end;

[0027] Step 3.3) Clamp the right end clamp, mount the left end bracket, flatten the left end face to the designed size, and machine the welding groove;

[0028] Part 4: Welding the cylinder bottom:

[0029] Step 4) Weld the main body and bottom of the cylinder together.

[0030] Based on the above, in step 1.7), the first chamfer is a 45° chamfer, the first step size is Φ(d3+1)×4mm, and the second chamfer is a 20° chamfer.

[0031] Based on the above, before the start of high-speed laser cladding, the distance between the powder feeding nozzle and the inner surface of the cylinder is adjusted to 10~15mm, the thickness of one cladding layer is 0.2~1.2mm, and the total thickness of two chamfer cladding layers is 0.4~2.4mm.

[0032] Based on the above, in the high-speed laser cladding process, the powder composition is: Cr: 16.5~30%; Ni: 0.2~10%; Mn: 0.1~0. 5%; Mo: 0.2~3%; Nb: 0.2~1.2%; the cladding parameters are set: power 4000~6000W, spot diameter Φ3~4mm, laser wavelength 1000~1200nm, line speed 3~8m / min, powder feeding amount 20~35g / min, coaxial shielding gas 15~22L / min, powder carrier gas flow 5~10L / min.

[0033] Based on the above, in step 3.1), the inner hole 14 of the oil cylinder is scraped and rolled according to the size of the drawing, and the effective thickness of the single-side cladding layer is 0.1~0.9mm.

[0034] Based on the above, in step 3.2), the surface of the cladding layer is polished and smooth after cladding, and the hardness range is 350-380HV; after scraping and rolling, the surface hardness of the cladding layer on the inner hole of the cylinder is 420~430HV; the inner hole of the cylinder is sampled to measure the micro-gradient hardness, the gradient hardness of the cladding layer is 350~370HV, the hardness of the heat-affected zone is 260~290HV, and the hardness of the substrate is 240~260HV.

[0035] Based on the above, in step 2.1), use a dial indicator to measure the inner hole radial runout, which is required to be ≤0.1mm.

[0036] Based on the above, in step 1.4), the inner hole is precision bored to Φ(d1+2a), the effective thickness a of the cladding layer on one side can be selected in the range of 0.2~1.2mm, and the roughness Ra0.4~6.3, where d1 is the inner diameter of the scraper surface.

[0037] Based on the above, in step 1.6), the stopper at the cylinder mouth is (L3-2) × Φ(d2+2a), the right end of the stopper is chamfered at (L5+1) × 30°, and the left end of the stopper is chamfered at 2 × 45°, where L3 is the length of the stopper section, d2 is the inner diameter of the stopper, and L5 is the axial length of the chamfer at the right end of the stopper.

[0038] Based on the above, in step 4), the welding parameters are: the backing welding parameters are welding current of 220~250A, welding voltage of 23.2~28.6V, and backing welding speed of 230~260m / min; the cover welding parameters are welding current of 250~300A, welding voltage of 28~31V, and backing welding speed of 260~300m / min; after welding, the girth weld is subjected to UT flaw detection to ensure that there are no cracks or pore defects.

[0039] The present invention has outstanding substantive features and significant progress compared to the prior art. Specifically, the present invention has the following advantages:

[0040] 1. Considering the strength of the thread, there should be no copper on the inner surface of the thread segment. Therefore, the inner surface of the thread segment after scraping and rolling is not processed, and it is consistent with the scraping and rolling surface, thereby ensuring its performance.

[0041] 2. Since it is not easy for the cladding equipment to clad the steps and transition chamfers in the inner hole of the cylinder, in this solution, chamfers are respectively set at the inner and outer ends of the stop, and the first chamfer, the first step and the second chamfer are set at the transition between the threaded section and the scraping surface to ensure a smooth transition and ensure the smooth progress of the cladding process.

[0042] 3. The cladding process of the inner hole adopts high-speed laser cladding technology throughout the whole process. The powder type is selected according to the needs, such as stainless steel powder or copper powder, etc. The power of the inner hole high-speed cladding is 4000-6000W, and the cladding line speed is 3-8m / min. Compared with the traditional laser cladding technology, the cladding line speed is increased by 3-8 times, and the corresponding line energy will be reduced to 1 / 8-1 / 3 of the traditional laser cladding. On the one hand, the reduction of line energy helps to reduce the dilution rate, maximize the purity of the cladding layer, and give full play to the performance of the cladding layer; on the other hand, the reduction of line energy will also reduce the heat input to the substrate, avoid changes in the organizational properties of the substrate material, and on the third hand, the reduction of line energy reduces the stress release deformation of the cylinder, which is convenient for subsequent processing. And because the heat generation of the entire cladding process is small, the cladding thickness is thin, the thermal deformation of the cylinder is small, and the size and accuracy of other positions of the cylinder are little affected.

[0043] 4. The cladding path is from the bottom of the cylinder to the stop, and two layers are clad in the chamfer transition area to avoid insufficient cladding thickness due to complex structure.

[0044] 5. The inner hole powder high-speed cladding process has a thin inner hole cladding layer, small heat input, small thermal deformation of the cylinder, and does not affect the size and shape accuracy of other parts of the cylinder. The inner hole welding end of the cylinder can be scraped and rolled as a whole without leaving steps. During the circumferential seam welding process, the copper layer will not melt into the circumferential seam, resulting in defects such as pores and cracks in the weld.

[0045] 6. The maximum hardness of the cylinder barrel powder high-speed cladding layer is 350~380HV. In order to ensure the roughness of the inner hole of the cylinder barrel, the boring tool and scraper ensure the size of the inner hole of the cylinder barrel during the scraping and rolling process, and the whole circle of ball rolling ensures the roughness of the inner hole Ra0.08-0.4. Due to the pressure of the ball, the surface hardness of the cladding layer of the inner hole of the cylinder barrel is increased to a maximum of 420~430HV. At the same time, the hardness decreases from the surface of the cladding layer to the substrate. This processing method not only improves the surface roughness of the inner hole of the cylinder barrel, but also increases the surface hardness, thereby improving the surface wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a structural schematic diagram of the cylinder body of the present invention.

[0047] Figure 2 It is a schematic structural diagram of the main finished product of the cylinder barrel of the present invention.

[0048] Figure 3 It is a schematic diagram of the structure of the outer circular frame nest during the cylinder barrel processing of the present invention.

[0049] Figure 4-1 It is a schematic diagram of the relative size structure of various diameter-changing parts in the cylinder bore machining process of the present invention.

[0050] Figure 4-2 for Figure 4-1 Enlarged view of point A in the middle.

[0051] Figure 5 It is the gradient hardness of the cross section of the cladding layer of the present invention.

[0052] Description of reference numerals:

[0053] In the figure: 1, cylinder barrel; 2, cylinder bottom; 11, accessories; 12, stopper; 13, inner surface of threaded section; 14, scraper surface; 15, right end clamp; 16, right end frame socket; 17, left end frame socket; 18, left end clamp;

[0054] 21. First chamfer; 22. First step; 23. Second chamfer. DETAILED DESCRIPTION

[0055] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0056] like Figure 1-Figure 5 As shown, a method for high-speed powder cladding processing of the inner hole of an oil cylinder is described. Taking the cylinder barrel Φ320*1606 as an example, the inner hole cladding powder thickness requirement is 0.4mm, the cladding powder is stainless steel powder, and the structure of the cylinder barrel 1 enclosing the cylinder bottom 2 is taken as an example for explanation. In other embodiments, the cladding powder can also be selected from other powder types such as copper powder.

[0057] Follow these steps:

[0058] Part 1: Processing before cladding:

[0059] The first step is blanking. The blanking adopts a cold drawn tube (no need for heat treatment) Φ377 / 320×1612 cylinder 1, which is processed by a sawing machine;

[0060] The second step is shot blasting, in which the cylinder 1 is shot blasted as a whole to remove the surface oxide skin;

[0061] The third step is to chamfer, use a three-jaw chuck to support the inner holes at both ends of the cylinder 1, and turn the left and right end surfaces of the cylinder 1 by 1.5mm. Turn the outer chamfers 15 and 20 at the right and left ends to 5×30°.

[0062] Step 4: Weld the upper cavity and weld the cylinder barrel accessories 11 according to the process requirements of the drawing (weld the accessories 11, i.e. the upper cavity joint seat, before scraping and rolling to prevent the inner hole of the cylinder barrel 1 from being deformed due to welding);

[0063] The fifth step is fine boring. Use scraping and rolling equipment FT45 to fine bore the inner hole 14 to Φ(d1+2a), where a=0.4, Φd1=Φ320(+0.14,0)mm, and the inner hole roughness Ra0.4~6.3;

[0064] Step 6: Use soft claws to support the inner holes at both ends of the cylinder 1, and machine the right and left two frame holes 17 and 18 to be Φ (D1-2) (0, -0.2) × 90 mm, the right and left two ends of the outer circle clamp heads 16 and 19 to be Φ (D1-2) (0, -0.2) × 10 mm, and the right and left two ends of the outer circle chamfers 15 and 20 to be 5 × 30°. Among them, ΦD1 = Φ377mm.

[0065] Then the left end clamping claw is fixed, and the right end frame nest center frame 17 is set. Considering the use strength of the thread, there should be no copper on the surface and the cladding equipment is not easy to melt the right angle. The stopper 12 at the cylinder mouth is (L3-2) ×Φ(d2+2a), the right end of the stopper 12 is (L5+1) ×30° chamfered, and the left end of the stopper 12 is 2×45° chamfered. Among them, L3=70, Φd2=Φ332(+0.14,0), L5=6.

[0066] Considering that the cylinder mouth cannot be clad in multiple layers, the outer round frame nest cannot support the cylinder mouth without a positioning reference, and the long claws have poor rigidity when supporting the scraping surface, the inner surface 13 of the thread section is not processed, and is consistent with the scraping surface 14. The left end face of the thread 13 is first machined with a 45° first chamfer 21 to transition to the first step 22 of Φ(d3+ 1)×4, and then the second chamfer 23 of 20° is machined to transition to the scraping surface 14, where Φd3=Φ332(+0.14,0)mm. Cutting speed: 120~160m / min, rotation speed 191~254r / min, feed rate 0.1~0.15mm / r; (the structure of the inner hole of the cylinder before melting is as follows Figure 4-1 and Figure 4-2 shown)

[0067] Step 7: Inner hole cladding. The clamping claw clamps the left end of the clamping head 19 and the right end of the bracket 17. Use a dial indicator to measure the radial runout of the inner hole, which is required to be ≤0.1mm. Extend the inner hole laser cladding gun head from the cylinder mouth end to the cylinder tail, take the cylinder tail end face as the cladding starting point, and adjust the distance between the powder feeding nozzle and the inner surface of the cylinder to 10~15mm. Set the cladding path: Starting from the cylinder tail, the scraping surface 14, the second chamfer 23 of 20° on the right side of the scraping surface, the first step 22 of Φ(d3+ 1)×4mm and the first chamfer 21 of 45° on the right side, the inner surface 13 of the threaded section, the transition chamfer between the inner surface 13 of the threaded section and the stop 12, and the chamfer (L5+1)×30° on the right side of the stop 12 are clad in one layer. Since the cladding at the chamfer is difficult and the cladding layer is thin, in order to meet the requirements of the drawing, each chamfered part is then re-melted in one layer. The thickness of one cladding layer is 0.9-1.0mm, and the total thickness of two chamfer cladding layers is 1.6-2.0mm.

[0068] The powder composition is as follows: Cr: 16.5~30%; Ni: 0.2~10%; Mn: 0.1~0. 5%; Mo: 0.2~3%; Nb: 0.2~1.2%, etc. The cladding parameters are set as follows: power 4000~6000W, spot diameter Φ3~4mm, laser wavelength 1000-1200nm, line speed 3~8m / min, powder feeding amount 20~35g / min, coaxial shielding gas 15~22L / min, powder carrier gas flow 5~10L / min.

[0069] Step 8: Scrape and roll. Chamfer the outer edges of the top cylinder barrel by 15 and 20. The scraper head enters from the cylinder mouth and scrapes the inner hole of the entire cylinder barrel to Φd1. The roughness is Ra≤0.4, Φd1=Φ320 (+0.14, 0) mm, and the effective thickness of the single-sided cladding layer is 0.4~0.5mm. Set the parameters of the boring tool and scraper: cutting speed 120~130m / min, rotation speed 191~207r / min, feed rate 1~1.2mm / r, and tool movement 191~248 m / min. Among them, the boring tool back cutting amount is 0.2~1mm, the scraper back cutting amount is 0.2~0.6mm, and the ball interference is 0.1~0.2mm.

[0070] After scraping and rolling, the surface hardness of the inner hole of the cylinder is 420~430HV. A 15*15*15mm sample is taken from the inner hole of the cylinder, and ground and polished. The surface roughness is Ra0.2~0.4, and the cross-section microhardness test is performed. When testing the hardness, the measurement is performed every 0.1mm along the gradient direction from the top layer of the cladding layer to the substrate: the gradient hardness of the cladding layer is 350~370HV, the hardness of the heat-affected zone is 260~290HV, and the hardness of the substrate is 240~260HV. The hardness curve is as follows Figure 5 shown.

[0071] It should be noted that the grinding and polishing steps are for better measuring and observing the microhardness indentation, so as to obtain the hardness value more accurately. They are not necessary steps and are only used in some embodiments.

[0072] Step 9: Turn the stopper 12. Because the number of cladding layers of the inner hole powder high-speed cladding process cannot exceed two layers, the cylinder mouth is not melted to the scraping surface size. In addition, avoid the problem of poor rigidity when the long clamping claw supports the scraping surface. In order to ensure the machining accuracy of the stopper, the soft clamping claw supports the two end surfaces of the inner hole of the cylinder barrel 1 (the left end supports the cylinder barrel scraping surface 14, and the right end supports the inner surface of the threaded section 13), and the right and left two places are turned. The frame nests 17 and 18 are Φ (D1-3) (0, -0.2) × 90 mm, and the outer circle clamps 16 and 19 at the right and left ends are turned to Φ (D1-3) (0, -0.2) × 10 mm. Among them, ΦD1=Φ377mm. Then clamp the outer circle 19 at the left end, set the frame nest 17 at the right end, start programming from the cylinder mouth end according to the finished product size of the drawing, and turn the stopper 12 and thread 13. Processing parameters: cutting speed: 80~100m / min, rotation speed 127~159r / min, feed rate 0.05~0.1mm / r.

[0073] Step 10: Carry out bevel, clamp the right end clamp head 16 to the left end frame socket 18, flatten the left end surface to the total length L±0.5 mm, L=1606mm, and carve the welding bevel according to the finished product size in the drawing;

[0074] The eleventh step is to weld the cylinder bottom. The cylinder barrel 1 and the cylinder bottom 2 are welded together. The welding parameters are as follows: the welding current of the base welding is 220~250A, the welding voltage is 23.2~28.6V, and the welding speed of the base welding is 230~260m / min; the welding parameters of the cover surface are as follows: the welding current is 250~300A, the welding voltage is 28~31V, and the welding speed of the base welding is 260~300m / min; after welding, the UT flaw detection is performed on the girth weld, and there are no defects such as cracks and pores.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A high-speed laser cladding manufacturing method for the inner hole of a cylinder, characterized in that: The following steps are involved: Part 1: Processing before cladding: Step 1.1) Use cold drawn tube blanks as the main body of the cylinder, and shot blast to remove the oxide scale; Step 1.2) Support the inner holes at both ends of the cylinder, turn the left and right end surfaces of the cylinder, and turn the outer round chamfers of the left and right end surfaces; Step 1.3) Weld the cavity joint seat; Step 1.4) Fine boring of inner hole; Step 1.5) For the inner holes at both ends of the support cylinder, turn the left and right support holes in turn, turn the outer circle clamps at the left and right ends, and further turn the left and right outer circle chamfers; Step 1.6) Keep the left inner support stationary, set the right end frame nest center frame, turn the cylinder mouth end stop, turn the right end and left end chamfer of the stop; Step 1.7) The inner surface of the thread segment is not processed, and the thread segment is kept consistent with the scraping surface. The first chamfer is turned on the left end face of the thread segment to transition to the first step, and then the second chamfer is turned to transition to the scraping surface; Part 2: Inner hole high-speed laser cladding: Step 2.1) Clamp the left end of the clamp head and the right end of the rack to ensure that the inner hole radial runout is within the set range. The inner hole radial runout is required to be ≤0.1mm; extend the inner hole laser cladding gun head from the cylinder mouth end to the cylinder tail end, with the cylinder tail end as the cladding starting point, and set the cladding path as: scraping surface, the second chamfer on the right side of the scraping surface, the first step, the first chamfer, the inner surface of the thread segment, the transition chamfer between the inner surface of the thread segment and the stop, the stop and the chamfer on the right end of the stop, cladding one layer; Step 2.2) Remelt another layer at each chamfer; Part 3: High-speed laser cladding and finishing: Step 3.1) Scrape and roll, chamfer the outer edges of both ends of the top cylinder, and insert the scraper head from the cylinder mouth to scrape and roll the entire cylinder bore to the set size; Step 3.2) Support the scraping surface of the cylinder barrel at the left end, support the inner surface of the threaded section of the cylinder barrel at the right end, machine the left and right two places, machine the outer circle clamps at the right and left ends, then clamp the outer circle of the left end, support the right end of the frame, and start machining the stop and the inner surface of the threaded section from the cylinder mouth end; Step 3.3) Clamp the right end clamp head, mount the left end bracket, flatten the left end face to the designed size, and machine the welding groove; Part 4: Welding the cylinder bottom: Step 4) Weld the main body and bottom of the cylinder together.

2. The high-speed laser cladding manufacturing method for the inner hole of the oil cylinder according to claim 1 is characterized in that: In step 1.7), the first chamfer is a 45° chamfer, the first step size is Φ(d3+1)×4mm, and the second chamfer is a 20° chamfer, where Φd3=Φ332(+0.14, 0)mm.

3. The high-speed laser cladding manufacturing method for the inner hole of the oil cylinder according to claim 2 is characterized in that: Before high-speed laser cladding begins, the distance between the powder feeding nozzle and the inner surface of the cylinder is adjusted to 10~15mm, the thickness of one cladding layer is 0.2~1.2mm, and the total thickness of two chamfer cladding layers is 0.4~2.4mm.

4. The high-speed laser cladding manufacturing method for the inner hole of the oil cylinder according to claim 3 is characterized in that: In the high-speed laser cladding process, the powder composition used is: Cr: 16.5~30%; Ni: 0.2~10%; Mn: 0.1~0. 5%; Mo: 0.2~3%; Nb: 0.2~1.2%; set cladding parameters: power 4000~6000W, spot diameter Φ3~4mm, laser wavelength 1000~1200nm, line speed 3~8m / min, powder feeding amount 20~35g / min, coaxial shielding gas 15~22L / min, powder carrier gas flow 5~10L / min.

5. The high-speed laser cladding manufacturing method for the inner hole of the oil cylinder according to claim 4 is characterized in that: In step 3.1), the inner hole of the oil cylinder is scraped and rolled according to the drawing dimensions, and the effective thickness of the single-sided cladding layer is 0.1~0.9mm.

6. The method for manufacturing the inner hole of a cylinder by high-speed laser cladding according to any one of claims 1 to 5, characterized in that: After step 3.1), the surface of the cladding layer was polished and smooth after cladding, and the hardness range was 350-380HV; after scraping and rolling, the surface hardness of the cladding layer on the inner hole of the cylinder was 420~430HV; the inner hole of the cylinder was sampled to measure the micro-gradient hardness, the gradient hardness of the cladding layer was 350~370HV, the hardness of the heat-affected zone was 260~290HV, and the hardness of the substrate was 240~260HV.

7. The high-speed laser cladding manufacturing method for the inner hole of the oil cylinder according to claim 6 is characterized in that: In step 2.1), use a dial indicator to measure the inner hole radial runout.

8. The method for manufacturing the inner hole of a cylinder by high-speed laser cladding according to claim 7, characterized in that: In step 1.4), the inner hole is precision bored to Φ(d1+2a), the effective thickness a of the cladding layer on one side ranges from 0.2 to 1.2 mm, and the roughness Ra is 0.4 to 6.3, where d1 is the inner diameter of the scraper surface.

9. The method for manufacturing the inner hole of a cylinder by high-speed laser cladding according to claim 8, characterized in that: In step 1.6), the stopper at the cylinder mouth is (L3-2) ×Φ(d2+2a), the right end of the stopper is chamfered (L5+1) ×30°, and the left end of the stopper is chamfered 2×45°, where L3 is the length of the stopper section, d2 is the inner diameter of the stopper, and L5 is the axial length of the chamfer at the right end of the stopper.

10. The method for manufacturing the inner hole of a cylinder by high-speed laser cladding according to claim 9, characterized in that: In step 4), the welding parameters are as follows: the backing welding parameters are welding current of 220~250A, welding voltage of 23.2~28.6V, and backing welding speed of 230~260m / min; the cover welding parameters are welding current of 250~300A, welding voltage of 28~31V, and backing welding speed of 260~300m / min; after welding, the girth weld is subjected to UT flaw detection to ensure that there are no cracks or pore defects.

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