A batch heat treatment method for large hydraulic cylinder barrels

Abstract

The application discloses a batch heat treatment method for large hydraulic cylinder barrels, which comprises the following steps: step S1, optimizing the chemical composition of the large hydraulic cylinder barrels; and step S2, quenching and tempering heat treatment of the large hydraulic cylinder barrels, wherein the quenching and tempering process comprises: quenching and tempering step 1, placing the large hydraulic cylinder barrels into a heating furnace through furnace loading tools, raising the temperature of the large hydraulic cylinder barrels to (880-890) ± 10 DEG C, taking the large hydraulic cylinder barrels out of the furnace after 3 hours of heat preservation, placing the large hydraulic cylinder barrels into a water tank through a lifting tool for water cooling, and then transferring the large hydraulic cylinder barrels into a tempering furnace; and quenching and tempering step 2, placing the large hydraulic cylinder barrels into a heating furnace through furnace loading tools, raising the temperature to (570-580) ± 10 DEG C, taking the large hydraulic cylinder barrels out of the furnace after heat preservation for 5 hours, and air cooling. The batch heat treatment method for the large hydraulic cylinder barrels can realize batch heat treatment of the large hydraulic cylinder barrels, improve the heat treatment efficiency, effectively guarantee the stability of the comprehensive mechanical properties of the large hydraulic cylinder barrels after heat treatment, and improve the production efficiency and the product processing quality.

Description

Technical Field

[0001] This invention relates to a heat treatment method for hydraulic cylinder barrels, and more particularly to a method for mass heat treatment of large hydraulic cylinder barrels. Background Technology

[0002] A mining car is a type of transport vehicle, and the hydraulic cylinder is one of its important components. Due to the large size of mining cars, the hydraulic cylinder is also large in size to ensure sufficient load-bearing capacity, classifying it as a large hydraulic cylinder. The cylinder barrel, which makes up this large hydraulic cylinder, is also quite large. This large hydraulic cylinder barrel is forged from 1E1058 steel. 1E1058 is a steel grade with well-balanced comprehensive mechanical properties, corresponding to the domestic grade 30CrMo and the American grade AISI 4130. In medium-sized machinery manufacturing, it is mainly used to manufacture tempered parts with large cross-sections that operate under high stress conditions. (See the attached instruction manual.) Figure 6 As shown, the large hydraulic cylinder barrel processed from 1E1058 material has a blind hole 71 at the center of its rear end. During the forging process, the large hydraulic cylinder barrel needs to be placed in a water tank for quenching. However, the existing cooling water tank has a slow overall flow rate. The circulation structure is that water is pumped from the middle to the lower pipe and the water flows from bottom to top. The average flow rate is about 0.1 m / s to 0.2 m / s, and the near-surface limit flow rate is about 0.6 m / s. When the large hydraulic cylinder barrel is quenched in the water tank, the water circulation in the blind hole 71 area is poor, so it is not easy to harden and penetrate. The comprehensive mechanical properties after heat treatment are unstable. In addition, due to the limitation of the hoisting structure, it is difficult to achieve batch heat treatment for the existing large hydraulic cylinder barrel, and the processing efficiency is not high. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a batch heat treatment method for large hydraulic cylinder barrels that can ensure the stability of the comprehensive mechanical properties of the product after heat treatment.

[0004] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: a method for batch heat treatment of large hydraulic cylinder barrels, comprising the following steps: Step S1. Chemical composition optimization: The chemical composition of the large hydraulic cylinder barrel made of 1E1058 material was optimized. The content of the main elements (wt) was adjusted to: C: 0.28~0.31%, Mn: 0.50~0.65%, Cr: 1.00~1.18%, Ni: 0.15~0.26%, Mo: 0.20~0.25%, and the content of the remaining elements (wt) was: Si: 0.15~0.30%, P≤0.015%, S≤0.04%, Al: 0.025~0.055%, Co≤0.05%, Cu≤0.035%, with the balance being Fe; Step S2. Heat treatment process and cooling: The large hydraulic cylinder barrel undergoes quenching and tempering heat treatment and cooling effect optimization, wherein the quenching and tempering process includes: Tempering step 1: The large hydraulic cylinder is placed into the heating furnace through the furnace loading tool and its temperature is raised to (880~890)±10℃. After holding at the temperature for 3 hours, it is taken out of the furnace and placed into the water tank for water cooling using a special lifting tool, and then transferred to tempering. Tempering step 2: Place the large hydraulic cylinder into the heating furnace through the furnace loading tool, raise its temperature to (570~580)±10℃, keep it at the temperature for 5 hours, and then remove it from the furnace and air cool it.

[0005] Furthermore, in the tempering step 1, the furnace temperature is raised from ≤400℃ to (880~890)±10℃ over 8~10 hours, held for 3 hours, and the transfer time from quenching out of the furnace to complete immersion in water is controlled to ≤80s, and the water cooling time is ≥6 minutes.

[0006] Furthermore, in the conditioning step 2, the furnace temperature is raised from ≤350℃ to (570~580)±10℃ over 6~8 hours and held for 5 hours before being removed from the furnace and air-cooled.

[0007] Furthermore, the furnace charging fixture includes a long strip-shaped pad with an inverted "T" shaped end. There are two sets of the pad, which are symmetrically arranged front and back. The large hydraulic cylinder has multiple sets, which are arranged side by side at equal intervals along the length of the pad.

[0008] Furthermore, the top of the pad has two layers of large hydraulic cylinders arranged side by side at equal intervals, with the upper and lower layers of large hydraulic cylinders staggered vertically.

[0009] Furthermore, the lifting device consists of a lifting beam and a lifting frame; the lifting beam has a rectangular frame structure, which consists of two horizontal beams symmetrically arranged front and back, and two longitudinal beams symmetrically arranged at the left and right ends of the two horizontal beams; the lifting frame has an inverted "Π" shaped structure, which has two sets, symmetrically arranged front and back, with the left and right ends of the lifting frame respectively axially connected to the left and right longitudinal beams near the top, and the front and rear ends of the large hydraulic cylinder are respectively mounted on the front and rear sets of lifting frames.

[0010] Furthermore, the hanger consists of a boom and a connecting rod. The boom has two sets, symmetrically arranged on the left and right sides of the connecting rod. A shaft is provided at the upper end near the top. The top of the longitudinal beam is provided with an upward-opening "U"-shaped shaft groove. The shaft is located in the shaft groove. The hanger can swing back and forth relative to the hanger beam through the shaft and shaft groove that are shaft-connected.

[0011] Furthermore, the top of the longitudinal beam has multiple symmetrically arranged shaft grooves on both the front and rear sides at equal intervals; the connecting rod has several sets of limiting devices arranged at equal intervals along its length, each set of limiting devices consisting of two limiting blocks arranged in parallel.

[0012] Furthermore, a limit stop is provided on the outer side of one of the sets of hangers, and the rear end of the large hydraulic cylinder with a blind hole placed on the hanger corresponds to the limit stop. A joint for easy chain connection is provided on the crossbeam on the same side as the limit stop, and the joint is fixedly welded to the center of the outer side of the crossbeam.

[0013] Furthermore, the water tank contains two submersible mixers arranged at an angle to each other.

[0014] Compared with the prior art, the advantages of this invention are: this method for batch heat treatment of large hydraulic cylinders can realize batch heat treatment of large hydraulic cylinders, improve the efficiency of heat treatment, effectively ensure the stability of the comprehensive mechanical properties of large hydraulic cylinders after heat treatment, is easy to operate, improves production efficiency, and ensures the quality of product processing. Attached image description: Figure 1 This is a schematic diagram of the side structure of the lifting device in this invention; Figure 2 This is a top view schematic diagram of the lifting device structure in this invention; Figure 3 This is a schematic diagram of the front structure of the lifting device in this invention; Figure 4 This is a schematic diagram of the lifting device for hoisting large hydraulic cylinders in this invention; Figure 5 This is a schematic diagram of the horizontal arrangement of the double-layer large hydraulic cylinders in the lifting device of this invention; Figure 6 This is a schematic diagram of the side structure of the large hydraulic cylinder in this invention; Figure 7 This is a schematic diagram of the end face structure of the furnace loading tooling and the large hydraulic cylinder after assembly in this invention; Figure 8 This is a side view of the furnace charging fixture and the large hydraulic cylinder after assembly in this invention. Figure 9 This is a side view of the water tank flow field in this invention; Figure 10 This is a top view of the water tank flow field in this invention; Figure 11 This is a schematic diagram of the quenching structure of the large hydraulic cylinder in this invention; Figure 12 This is a process curve diagram of quenching and tempering of the large hydraulic cylinder barrel of the present invention.

[0015] In the diagram: 1. Crossbeam; 11. Joint; 2. Longitudinal beam; 21. Shaft joint groove; 3. Hanger; 31. Hoist; 311. Shaft; 32. Connecting rod; 4. Stop; 5. Limiting block; 6. Bracket; 61. Rear bracket; 62. Positioning block; 63. Front bracket; 7. Large hydraulic cylinder; 71. Blind hole; 8. Shim; 9. Water tank; 91. Submersible mixer. Detailed implementation method: The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0016] A method for mass heat treatment of large hydraulic cylinder barrels includes the following steps: Step S1. Chemical composition optimization: Taking into account factors such as weldability, overall hardness, hardenability, and low-temperature impact, the chemical composition of the large hydraulic cylinder barrel 7 made of 1E1058 material was optimized. The content of the main elements (wt) was adjusted to: C: 0.28~0.31%, Mn: 0.50~0.65%, Cr: 1.00~1.18%, Ni: 0.15~0.26%, Mo: 0.20~0.25%, and the content of the remaining elements (wt) was: Si: 0.15~0.30%, P≤0.015%, S≤0.04%, Al: 0.025~0.055%, Co≤0.05%, Cu≤0.035%, with the balance being Fe; Step S2. Heat treatment process and cooling: The large hydraulic cylinder barrel 7 undergoes quenching and tempering heat treatment and cooling effect optimization, including, for example... Figure 12 As shown, the conditioning process includes: Tempering Step 1: The large hydraulic cylinder 7 is placed into the heating furnace using furnace loading fixtures, and its temperature is raised to (880~890)±10℃. After holding at this temperature for 3 hours, it is removed from the furnace and placed into the water tank 9 for quenching and water cooling using a special lifting tool, followed by tempering. Specifically, the furnace temperature is raised from ≤400℃ to (880~890)±10℃ over 8~10 hours, held for 3 hours, and the transfer time from removing it from the furnace to complete immersion in water is controlled to ≤80s, with a water cooling time ≥6 minutes. Figure 9 and Figure 10 As shown, in order to improve the cooling effect of the large hydraulic cylinder 7, the water tank 9 has two submersible mixers 91 arranged at an angle. The two submersible mixers 91 arranged at a certain angle make the cooling water flow rate in the water tank 9 reach the expected value, and define the effective quenching area. In the effective quenching area, the main flow rate can reach 0.6-1.0M / S. Tempering step 2: Place the large hydraulic cylinder 7 into the heating furnace through the furnace loading tool, raise its temperature to (570~580)±10℃, hold it at that temperature for 5 hours, and then remove it from the furnace and air cool it. Specifically, raise the furnace temperature from ≤350℃ to (570~580)±10℃ over 6~8 hours, hold it at that temperature for 5 hours, and then remove it from the furnace and air cool it.

[0017] like Figure 7 and Figure 8 As shown, in order to achieve batch heat treatment of large hydraulic cylinders 7 and improve production efficiency, the furnace charging fixture includes a long strip-shaped pad 8. The end of the pad 8 is an inverted "T" shape, and there are two sets of pads symmetrically arranged front and back. There are multiple sets of large hydraulic cylinders 7, which are arranged side by side at equal intervals along the length of the pad 8. The top of the pad 8 has two layers of large hydraulic cylinders 7 arranged side by side at equal intervals. The upper and lower layers of large hydraulic cylinders 7 are separated by a bracket 6, and the upper and lower layers of large hydraulic cylinders 7 are staggered vertically to ensure the tempering effect.

[0018] like Figure 1-3 As shown, in order to achieve batch hoisting and quenching treatment of large hydraulic cylinders 7, the hoisting device consists of a hoisting beam and a hoisting frame 3. The hoisting beam has a rectangular frame structure, which consists of two crossbeams 1 arranged symmetrically front to back and two longitudinal beams 2 arranged symmetrically at the left and right ends of the two crossbeams 1. The hoisting frame 3 has an inverted "Π" shaped structure, which has two sets, arranged symmetrically front to back. The left and right ends of the hoisting frame 3 are respectively axially connected to the left and right longitudinal beams 2 near the top. The front and rear ends of the large hydraulic cylinders 7 are respectively mounted on the front and rear sets of the hoisting frames 3. In order to prevent the large hydraulic cylinders 7 from slipping off the hoisting frame 3, a limit stop 4 is provided on the outer side of one set of the hoisting frame 3. The rear end of the large hydraulic cylinder 7 with blind hole 71 placed on the hoisting frame 3 corresponds to the limit stop 4. A joint 11 for easy chain connection is provided on the crossbeam 1 on the same side as the limit stop 4. The joint 11 is fixedly welded to the center of the outer side of the crossbeam 1. To facilitate the hoisting of the large hydraulic cylinder 7, the lifting frame 3 consists of a boom 31 and a connecting rod 32. The boom 31 has two sets, symmetrically arranged on the left and right sides of the connecting rod 32. A shaft 311 is provided at the upper end near the top. The top of the longitudinal beam 2 is provided with an upward-opening "U"-shaped shaft groove 21. The shaft 311 is located in the shaft groove 21. The lifting frame 3 can swing back and forth relative to the lifting beam through the shaft 311 and shaft groove 21 that are shaft connected.

[0019] To facilitate the adjustment of the spacing between the front and rear sets of hangers 3, and to accommodate the lifting of hydraulic cylinders of different sizes, the top of the longitudinal beam 2 is symmetrically provided with multiple equally spaced shaft connection slots 21 on both its front and rear sides. The spacing between the front and rear sets of hangers 3 can be adjusted by engaging the shaft 311 with the shaft connection slots 21 at different positions. Figure 3 As shown, to prevent the large hydraulic cylinder 7 from rolling on the lifting frame 3 and affecting the hoisting, several sets of limiting devices are arranged at equal intervals along the length of the connecting rod 32. Each set of limiting devices consists of two parallel limiting blocks 5, and the large hydraulic cylinder 7 is located between the two parallel limiting blocks 5; Figure 4 and Figure 5 As shown, the upper and lower layers of large hydraulic cylinders 7 can be hoisted on the hanger 3. The upper and lower layers of large hydraulic cylinders 7 are separated by a bracket 6, and the upper and lower layers of large hydraulic cylinders 7 are staggered vertically.

[0020] To facilitate the support of large hydraulic cylinders 7, the bracket 6 consists of a long rod-shaped rear bracket 61 and a front bracket 63. The front bracket 63 is positioned near the front end between the upper and lower layers of large hydraulic cylinders 7, and the rear bracket 61 is positioned near the rear end between the upper and lower layers of large hydraulic cylinders 7. The top and bottom of the rear bracket 61 are fixedly welded with positioning blocks 62 along its length to limit the left and right positions of the large hydraulic cylinders 7. There are several positioning blocks 62, and two sets of positioning blocks 62 form a set with each other, forming a limiting distance between them for engaging the large hydraulic cylinders 7. The positioning blocks 62 at the top and bottom of the rear bracket 61 are staggered vertically to ensure the quenching effect of the upper and lower layers of large hydraulic cylinders 7.

[0021] During heat treatment, such as Figure 11 As shown, several large hydraulic cylinders 7 are placed at equal intervals along the length of the shim 8 on top of the shim 8. Then, a support 6 is erected on top of the large hydraulic cylinders 7, and several large hydraulic cylinders 7 are placed at equal intervals along the length of the support 6. The large hydraulic cylinders 7 of the upper and lower layers are staggered. Then, they are sent into a heating furnace for heating, raising the cylinder temperature to (880~890)±10℃, and holding it at that temperature for 3 hours. Then, they are taken out of the furnace and moved to the top of the furnace loading fixture by a crane-driven hoist. The two sets of lifting frames 3 are opened and respectively fitted onto the bottom of the lower layer of large hydraulic cylinders 7 near the front and rear ends. The upper and lower large hydraulic cylinders 7 are lifted from the pads 8 and transferred to the water tank 9 for quenching and water cooling. After the lifting device is submerged in the water of the water tank 9, the chain connected to the top of the device on the connector 11 is fixed to the outside of the water tank 9. The lifting device swings and rotates in the water tank 9 due to the water flow. The stability of the heat preservation position is ensured. The transfer time of the large hydraulic cylinder 7 from the furnace to the complete immersion in water is controlled to ≤80s, and the water cooling time is ≥6 minutes. After water cooling, the upper and lower large hydraulic cylinders 7 are transferred back to the pads 8 and sent into the heating furnace for tempering. The cylinder temperature is raised to (570~580)±10℃. After heat preservation for 5 hours, the cylinders are taken out of the furnace and air cooled.

[0022] This method for batch heat treatment of large hydraulic cylinders enables batch heat treatment of large hydraulic cylinders, improves the efficiency of heat treatment, effectively ensures the stability of the comprehensive mechanical properties of large hydraulic cylinders after heat treatment, is easy to operate, improves production efficiency, and ensures the quality of product processing.

[0023] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for batch heat treatment of large hydraulic cylinder barrels, characterized in that, Includes the following steps: Step S1. Chemical composition optimization: The chemical composition of the large hydraulic cylinder barrel (7) of 1E1058 material was optimized. The content of the main elements was adjusted to: C: 0.28~0.31%, Mn: 0.50~0.65%, Cr: 1.00~1.18%, Ni: 0.15~0.26%, Mo: 0.20~0.25%, and the content of the remaining elements was: Si: 0.15~0.30%, P≤0.015%, S≤0.04%, Al: 0.025~0.055%, Co≤0.05%, Cu≤0.035%, with the balance being Fe; Step S2. Heat treatment process and cooling: The large hydraulic cylinder (7) undergoes quenching and tempering heat treatment and cooling effect optimization, wherein the quenching and tempering process includes: Tempering step 1: The large hydraulic cylinder (7) is placed into the heating furnace through the furnace loading fixture, and its temperature is raised to (880~890)±10℃. After holding for 3 hours, it is taken out of the furnace. The furnace loading fixture includes a long strip-shaped pad (8). The end of the pad (8) is an inverted "T" shape. It has two sets and is symmetrically arranged front and back. The large hydraulic cylinder (7) has multiple sets and is arranged in parallel at equal intervals along the length of the pad (8). The top of the pad (8) has two layers of large hydraulic cylinders (7) arranged in parallel at equal intervals. The two layers of large hydraulic cylinders (7) are staggered vertically. The large hydraulic cylinder (7) is placed into the water tank (9) for water cooling using a special lifting tool. The transfer time from taking out of the furnace to being fully immersed in water is controlled to be ≤80s. The water cooling time is ≥6 minutes. Then it is transferred to tempering. The lifting tool consists of a lifting beam and a lifting frame (3). The lifting beam has a rectangular frame structure and is composed of two symmetrically arranged front and back. The structure consists of a horizontal beam (1) and two longitudinal beams (2) symmetrically arranged at the left and right ends of the two horizontal beams (1); the hanger (3) has an inverted "Π" shaped structure, which has two sets, symmetrically arranged in front and back. The left and right ends of the hanger (3) are respectively axially connected to the left and right longitudinal beams (2) near the top. The front and rear ends of the large hydraulic cylinder (7) are respectively mounted on the front and rear sets of hangers (3); the hanger (3) consists of a boom (31) and a connecting rod (32). The boom (31) has two sets, symmetrically arranged on the left and right sides of the connecting rod (32). The upper end of the boom (31) is provided with a shaft (311) near the top. The top of the longitudinal beam (2) is provided with an upward-opening "U" shaped shaft groove (21). The shaft (311) is located in the shaft groove (21). The hanger (3) can swing back and forth relative to the hanging beam through the shaft (311) and shaft groove (21) that are axially connected. Tempering step 2: Place the large hydraulic cylinder (7) into the heating furnace through the furnace loading tool, raise its temperature to (570~580)±10℃, keep it at the temperature for 5 hours, and then remove it from the furnace and air cool it.

2. The method for batch heat treatment of large hydraulic cylinder barrels according to claim 1, characterized in that, In the conditioning step 1, the furnace temperature is increased from ≤400℃ to (880~890)±10℃ over 8~10 hours, and then held for 3 hours.

3. The method for batch heat treatment of large hydraulic cylinder barrels according to claim 1, characterized in that, In the conditioning step 2, the furnace temperature is raised from ≤350℃ to (570~580)±10℃ over 6~8 hours and held for 5 hours before being removed from the furnace and air-cooled.

4. The method for batch heat treatment of large hydraulic cylinder barrels according to claim 1, characterized in that, The top of the longitudinal beam (2) is symmetrically arranged with multiple shaft grooves (21) arranged at equal intervals on both the front and back sides of its center; the connecting rod (32) is provided with several sets of limiting devices arranged at equal intervals along its length direction, and each set of limiting devices consists of two limiting blocks (5) arranged in parallel.

5. A method for batch heat treatment of large hydraulic cylinder barrels according to claim 1, characterized in that, in one group The outer side of the hanger (3) is provided with a limit stop (4). The rear end of the large hydraulic cylinder (7) placed on the hanger (3) with a blind hole (71) corresponds to the limit stop (4). A connector (11) for easy chain connection is provided on the crossbeam (1) on the same side as the limit stop (4). The connector (11) is fixedly welded to the center of the outer side of the crossbeam (1).

6. A method for batch heat treatment of large hydraulic cylinder barrels according to claim 1, characterized in that, The water tank (9) contains two submersible mixers (91) arranged at an angle to each other.

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