A forklift piston body structure using non-quenched and tempered mechanical structural steel and a processing method thereof

Abstract

The present invention relates to a forklift piston body structure using non-quenched and tempered mechanical structural steel and a processing method thereof. The piston body structure includes a piston rod and a piston. The piston rod includes a piston rod base and hard chrome layer 1 and hard chrome layer 2 plated on the outer side of the piston rod base in sequence. The piston rod base uses non-quenched and tempered mechanical structural steel. A groove 1 is provided on the outer peripheral wall of the piston rod. A groove 2 and a groove 3 are provided on the inner peripheral wall of the piston. The piston is connected to the piston rod through a plurality of balls located in an annular cavity surrounded by groove 1 and groove 2. A seal is installed in groove 3. A connecting part is provided at each end of the piston rod. A connecting through hole and a U-shaped groove are provided on the connecting part. The center line of the U-shaped groove is in the same straight line with the center line of the piston rod. The center line of the connecting through hole is perpendicular to the center line of the U-shaped groove. The center line of the U-shaped groove is in the same straight line with the axial center line of the piston rod. The present invention has the advantages of high production efficiency, convenient maintenance and replacement, strong corrosion resistance and low cost.

Description

Technical Field

[0001] The invention relates to the technical field of forklifts, and in particular to a forklift piston body structure using non-quenched and tempered mechanical structural steel and a processing method thereof. Background Art

[0002] At present, the material used for forklift oil cylinder piston rod is mostly 45 steel quenched and tempered, and the processing procedures are: cutting - first turning - quenching and tempering - second turning - grinding outer circle - first polishing - chrome plating (single layer) - second polishing - welding - milling and boring. The existing piston rod and its processing procedures have the following shortcomings: 1. The quenching and tempering process and grinding process have a long cycle time and low production efficiency; 2. The piston rod has a large deformation after welding, and the piston rod is not easy to replace during maintenance, and the corrosion resistance of the piston rod is poor. Summary of the invention

[0003] The object of the present invention is to provide a forklift piston body structure using non-quenched and tempered mechanical structural steel and a processing method thereof, which can solve the deficiencies existing in the prior art and have the advantages of high production efficiency, convenient maintenance and replacement, strong corrosion resistance and low cost.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A forklift piston body structure using non-quenched and tempered mechanical structural steel includes a piston rod and a piston sleeved on the outside of the middle section of the piston rod. The piston rod includes a piston rod base and hard chrome layer 1 and hard chrome layer 2 plated on the outside of the piston rod base in sequence; the piston rod base is made of non-quenched and tempered mechanical structural steel; a groove 1 is provided on the outer peripheral wall of the piston rod; a groove 2 corresponding to the groove 1 is provided on the inner peripheral wall of the piston; the piston is connected to the piston rod through a number of balls located in an annular cavity surrounded by the groove 1 and the groove 2; a groove 3 is also provided on the inner peripheral wall of the piston; a seal is installed in the groove 3; a connecting part is provided at each end of the piston rod; a connecting through hole and a U-shaped groove are provided on the connecting part; the center line of the connecting through hole is perpendicular to the center line of the U-shaped groove; the center line of the U-shaped groove is on the same straight line as the axial center line of the piston rod.

[0006] Furthermore, the U-shaped groove divides the connecting part into two halves, an upper half and an lower half, a positioning hole is provided on the upper half, and the top of the upper half is a stepped surface.

[0007] Furthermore, the roughness of the surface of the piston rod substrate is not greater than Ra0.2 μm.

[0008] Furthermore, the thickness of the first hard chromium layer is 0.02 mm to 0.03 mm; the thickness of the second hard chromium layer is 0.02 mm to 0.03 mm.

[0009] Furthermore, a ball inlet communicating with the annular cavity is provided on the piston.

[0010] The present invention also relates to a method for processing the forklift piston body structure using the non-quenched and tempered mechanical structural steel, the method comprising the following steps:

[0011] (1) Cutting: Use non-quenched and tempered mechanical structural steel to prepare the piston rod base.

[0012] (2) Turning: Use a CNC machine tool to perform rough and fine machining on the outer circle of the piston rod base blank, and turn an arc-shaped groove on the outer circumference of the middle section of the piston rod base. After turning, the outer circle surface roughness of the piston rod base is not greater than Ra1.6um.

[0013] (3) First polishing: Use a centerless polishing machine to polish the piston rod base after machining for 2-3 times, so that the outer diameter of the piston rod base is reduced by 0.03mm-0.05mm and the outer surface roughness is not greater than Ra0.2um.

[0014] (4) First chrome plating: After the first polishing, the piston rod substrate is degreased, washed, and preheated and recoiled in sequence, and then hard chrome plating is performed on its surface using a low current density, so that a hard chrome layer 1 is attached to the surface of the piston rod substrate; the current density of the hard chrome plating operation is controlled at 20-30A / dm2, and the thickness of the hard chrome layer 1 is 0.02mm-0.03mm. Using low current density to electroplate hard chrome improves the corrosion resistance of hard chrome.

[0015] (5) Second polishing: Use a centerless polisher to polish the piston rod substrate after the first chrome plating. After this polishing, the outer diameter of the piston rod substrate does not decrease, and the outer surface roughness is not greater than Ra0.2um. The second polishing operation can improve the surface roughness of the piston rod substrate plated with the first hard chrome layer and improve the adhesion of the first and second hard chrome layers.

[0016] (6) Second chrome plating: After the second polishing, the piston rod substrate is degreased, washed, and preheated and recoiled in sequence, and then hard chrome plating is performed on its surface, so that the surface with hard chrome layer 1 is attached with hard chrome layer 2 to obtain a piston rod; the current density of this hard chrome plating operation is controlled at 30-50A / dm2, and the hard chrome thickness of hard chrome layer 2 is 0.02mm-0.03mm. By controlling the current density at 30-50A / dm2, the deposition efficiency of hard chrome can be improved.

[0017] (7) Third polishing: Use a centerless polisher to polish the piston rod once. After this polishing, the outer diameter of the piston rod base body does not decrease, and the outer surface roughness is no greater than Ra0.2um. The third polishing operation can improve the surface roughness of the piston rod.

[0018] (8) Boring and milling: Milling and boring are performed on the connecting parts of the two ends of the piston rod in sequence; milling and boring are performed before chrome plating to reduce bumps and scratches on the surface of the piston rod;

[0019] (9) Assembly: Assemble the piston rod and piston after boring and milling.

[0020] It can be seen from the above technical solutions that the present invention can solve the deficiencies in the prior art and has the advantages of high production efficiency, convenient maintenance and replacement, strong corrosion resistance and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the piston body structure in the present invention;

[0022] Figure 2 It is a structural schematic diagram of the piston rod in the present invention.

[0023] in:

[0024] 100. Piston rod, 101. Piston rod base, 102. Hard chrome layer 2, 103. Hard chrome layer 1, 104. Groove 1, 200. Piston, 201. Groove 3, 300. Ball, 400. Connecting part, 401. Connecting through hole, 402. U-shaped groove, 403. Step surface, 404. Positioning hole. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings:

[0026] like Figure 1-Figure 2The forklift piston body structure shown in the figure adopts non-quenched and tempered mechanical structural steel, including a piston rod 100 and a piston 200 sleeved on the outer side of the middle section of the piston rod 100. The piston rod 100 includes a piston rod base 101 and a hard chrome layer 103 and a hard chrome layer 2 102 plated on the outer side of the piston rod base 101 in sequence; the piston rod base 101 adopts non-quenched and tempered mechanical structural steel; a groove 104 is provided on the outer peripheral wall of the piston rod 100; a groove 2 corresponding to the groove 104 is provided on the inner peripheral wall of the piston 200; the piston 200 is connected to the piston rod 100 through a plurality of balls 300 located in the annular cavity surrounded by the groove 104 and the groove 2. A groove 3 201 is also provided on the inner peripheral wall of the piston 200; a seal is installed in the groove 3 201; the seal is located between the piston and the piston rod, and plays a sealing role to prevent oil leakage in the oil cylinder. After the piston rod base of the piston rod is fine-turned, it is then polished for the first time, plated with a hard chrome layer one, polished for the second time, plated with a hard chrome layer two, and polished for the third time in sequence. The surface roughness after each polishing treatment shall not be greater than Ra0.2μm. The present invention adopts non-quenched and tempered mechanical structural steel to make the piston rod, which can be used directly without quenching and tempering treatment. The outer diameter of the manufactured piston rod is reduced by 2mm relative to the 45 steel quenched and tempered, which reduces the processing allowance and cost of the material, improves the processing efficiency, and the material hardness of the manufactured piston rod is uniform, and the mechanical properties are equivalent to or even better than those of the 45 steel quenched and tempered. The cost of using non-quenched and tempered mechanical structural steel to make the piston rod can be reduced by 700-1000 yuan compared with 45 steel quenched and tempered by using 1 ton. Compared with the prior art in which the sealing groove is opened on the piston rod, the present invention sets a groove three as a sealing groove on the inner wall of the piston, which is convenient for processing, and the surface roughness and roundness of the groove are good, which greatly improves the sealing performance.

[0027] like Figure 2As shown, a connecting portion 400 is provided at each end of the piston rod 100. The two connecting portions 400 are symmetrically arranged with the center line of groove 1 as the axis of symmetry. The connecting portion 400 is used for assembly and connection with the steering axle. A connecting through hole 401 and a U-shaped groove 402 are provided on the connecting portion 400; the center line of the connecting through hole 401 is perpendicular to the center line of the U-shaped groove 402; the center line of the U-shaped groove 402 is on the same straight line as the axial center line of the piston rod. The U-shaped groove 402 divides the connecting portion 400 into two halves, an upper half, a positioning hole 404 is provided on the upper half, and the top of the upper half is a stepped surface 403. The positioning hole 404 is a threaded hole located on the inner side of the connecting through hole. The positioning hole 404 plays a positioning role in the process of assembling the piston rod 100 with the steering axle, ensuring the accuracy of the assembly of the piston rod and the steering axle. A stepped surface is milled on the top of the connecting portion, and the bottom is a horizontal surface. The stepped surface includes a horizontal surface 1, a longitudinal surface and a horizontal surface 2 which are connected in sequence. The horizontal surface 2 is used to assemble the piston rod and the steering axle together. Such a design can ensure the installation quality and improve the production efficiency. The present invention sets a U-shaped groove, and designs the U-shaped groove into two halves, which is used to place the connecting part of the axle on the one hand, and can also avoid stress concentration and damage to the piston rod during use on the other hand, thereby extending the service life of the piston rod. The connecting through hole is used to place a connecting pin, which connects the oil cylinder connecting part and the axle connecting part, and the top of the connecting pin is placed on the stepped surface 403. After the connecting pin connects the piston rod and the axle together, a bolt is used to pass through the threaded hole to fix the connecting pin to the connecting part 400.

[0028] Furthermore, the roughness of the surface of the piston rod substrate 101 is not greater than Ra0.2 μm.

[0029] Furthermore, the thickness of the hard chrome layer 1 102 is 0.02 mm to 0.03 mm; the thickness of the hard chrome layer 2 102 is 0.02 mm to 0.03 mm. Single-layer chrome plating generally causes pitting after 72 hours, while the present invention can generally achieve more than 120 hours of salt spray test by plating a double layer of hard chrome on the outer surface of the piston rod substrate. The current density of the hard chrome layer 1 is small, and the current density of the hard chrome layer 2 can be increased. The porosity of the hard chrome layer 1 is relatively low, which can improve the corrosion resistance. In the processing of the present invention, a polishing process is added between the two layers of chrome plating process, which can improve the adhesion of the coating.

[0030] Furthermore, the piston 200 is provided with a ball inlet connected to the annular cavity. The ball inlet is used to assemble the ball into the annular cavity. When assembling the piston and the piston rod, first put the seal in the groove three, then put the piston on the piston rod, and make the groove one and the groove two form an annular cavity, then inject the ball into the annular cavity from the ball inlet, and put the support ring and the seal for cylinder sealing on the piston.

[0031] The present invention also relates to a method for processing the forklift piston body structure using the non-quenched and tempered mechanical structural steel, the method comprising the following steps:

[0032] (1) Cutting: Use non-quenched and tempered mechanical structural steel to prepare the piston rod base.

[0033] (2) Turning: Use a CNC machine tool to perform rough and fine machining on the outer circle of the piston rod base blank, and turn an arc-shaped groove on the outer circumference of the middle section of the piston rod base. After turning, the outer circle surface roughness of the piston rod base is not greater than Ra1.6um.

[0034] (3) First polishing: Use a centerless polishing machine to polish the piston rod base after machining for 2-3 times, so that the outer diameter of the piston rod base is reduced by 0.03mm-0.05mm and the outer surface roughness is not greater than Ra0.2um.

[0035] (4) First chrome plating: After the first polishing, the piston rod substrate is degreased, washed, and preheated and recoiled in sequence, and then hard chrome plating is performed on its surface using a low current density, so that a hard chrome layer 1 is attached to the surface of the piston rod substrate; the current density of the hard chrome plating operation is controlled at 20-30A / dm2, and the thickness of the hard chrome layer 1 is 0.02mm-0.03mm. Using low current density to electroplate hard chrome improves the corrosion resistance of hard chrome.

[0036] (5) Second polishing: Use a centerless polisher to polish the piston rod substrate after the first chrome plating. After this polishing, the outer diameter of the piston rod substrate does not decrease, and the outer surface roughness is not greater than Ra0.2um. The second polishing operation can improve the surface roughness of the piston rod substrate plated with the first hard chrome layer and improve the adhesion of the first and second hard chrome layers.

[0037] (6) Second chrome plating: After the second polishing, the piston rod substrate is degreased, washed, and preheated and recoiled in sequence, and then hard chrome plating is performed on its surface, so that the surface with hard chrome layer 1 is attached with hard chrome layer 2 to obtain a piston rod; the current density of this hard chrome plating operation is controlled at 30-50A / dm2, and the hard chrome thickness of hard chrome layer 2 is 0.02mm-0.03mm. By controlling the current density at 30-50A / dm2, the deposition efficiency of hard chrome can be improved.

[0038] (7) Third polishing: Use a centerless polisher to polish the piston rod once. After this polishing, the outer diameter of the piston rod base body does not decrease, and the outer surface roughness is no greater than Ra0.2um. The third polishing operation can improve the surface roughness of the piston rod.

[0039] (8) Boring and milling: Milling and boring are performed on the connecting parts of the two ends of the piston rod in sequence; milling and boring are performed before chrome plating to reduce bumps and scratches on the surface of the piston rod;

[0040] (9) Assembly: Assemble the piston rod and piston after boring and milling.

[0041] The embodiments described above are merely descriptions of preferred implementation modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for processing a forklift piston body structure using non-quenched and tempered mechanical structural steel, wherein the forklift piston body structure comprises a piston rod and a piston sleeved on the outer side of the middle section of the piston rod; characterized in that: The piston rod comprises a piston rod base and hard chrome layer 1 and hard chrome layer 2 plated on the outside of the piston rod base in sequence; the piston rod base is made of non-quenched and tempered mechanical structural steel; a groove 1 is provided on the outer peripheral wall of the piston rod; a groove 2 corresponding to the groove 1 is provided on the inner peripheral wall of the piston; the piston is connected to the piston rod through a number of balls located in an annular cavity surrounded by the groove 1 and the groove 2; a groove 3 is also provided on the inner peripheral wall of the piston; a seal is installed in the groove 3; a connecting part is provided at each end of the piston rod; a connecting through hole and a U-shaped groove are provided on the connecting part; the center line of the connecting through hole is perpendicular to the center line of the U-shaped groove; the center line of the U-shaped groove is on the same straight line as the axial center line of the piston rod; The processing method of the forklift piston body structure using non-quenched and tempered mechanical structural steel comprises the following steps: (1) Cutting: Use non-quenched and tempered mechanical structural steel to prepare the piston rod base; (2) Turning: Use a CNC machine tool to perform rough and fine machining on the outer circle of the piston rod base blank, and turn an arc-shaped groove on the outer circumference of the middle section of the piston rod base. After turning, the outer circle surface roughness of the piston rod base is not greater than Ra1.6um; (3) First polishing: Use a centerless polishing machine to polish the piston rod base after machining for 2-3 times, so that the outer diameter of the piston rod base is reduced by 0.03mm-0.05mm and the outer surface roughness is not greater than Ra0.2um; (4) First chrome plating: After the first polishing, the piston rod substrate is degreased, washed, and preheated and recoiled in sequence, and then hard chrome plating is performed on its surface using a low current density, so that a hard chrome layer 1 is attached to the surface of the piston rod substrate; the current density of the hard chrome plating operation is controlled at 20-30A / dm2, and the thickness of the hard chrome layer 1 is 0.02mm-0.03mm; (5) Second polishing: Use a centerless polishing machine to polish the piston rod substrate after the first chrome plating. After this polishing, the outer diameter of the piston rod substrate does not decrease, and the outer surface roughness is not greater than Ra0.2um; (6) Second chrome plating: After the second polishing, the piston rod substrate is degreased, washed with water, and preheated and recoiled in sequence, and then hard chrome plating is performed on its surface, so that the surface with hard chrome layer 1 is attached with hard chrome layer 2 to obtain the piston rod; the current density of this hard chrome plating operation is controlled at 30-50A / dm2, and the hard chrome thickness of hard chrome layer 2 is 0.02mm-0.03mm; (7) Third polishing: Use a centerless polishing machine to polish the piston rod once. After this polishing, the outer diameter of the piston rod base does not decrease, and the outer surface roughness is not greater than Ra0.2um; (8) Boring and milling: Milling and boring are performed on the connecting parts of the two ends of the piston rod in sequence; milling and boring are performed before chrome plating to reduce bumps and scratches on the surface of the piston rod; (9) Assembly: Assemble the piston rod and piston after boring and milling.

2. The method for processing a forklift piston body structure using non-quenched and tempered mechanical structural steel according to claim 1, characterized in that: The U-shaped groove divides the connecting part into two halves, an upper half and an lower half, wherein a positioning hole is provided on the upper half, and the top of the upper half is a stepped surface.

3. The method for processing a forklift piston body structure using non-quenched and tempered mechanical structural steel according to claim 1, characterized in that: The roughness of the piston rod base surface is not greater than Ra0.2 μm.

4. The method for processing a forklift piston body structure using non-quenched and tempered mechanical structural steel according to claim 1, characterized in that: The thickness of the first hard chromium layer is 0.02 mm to 0.03 mm; the thickness of the second hard chromium layer is 0.02 mm to 0.03 mm.

5. The method for processing a forklift piston body structure using non-quenched and tempered mechanical structural steel according to claim 1, characterized in that: The piston is provided with a ball inlet which is communicated with the annular cavity.

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