Production process of tower crane screw

Abstract

The invention provides a tower crane screw production process, which comprises the following steps: wire pickling, wire annealing, wire drawing, screw forming, screw grinding and screw heat treatment, and combines a vacuum annealing process with a rotary swaging roller die reducing cold drawing process to improve the axial elongation and stretch rate of a material. Quenching equipment in the screw heat treatment step comprises an N-shaped fixing frame, a lifting mechanism, a heating and heat preservation mechanism, a conveying mechanism and a fan, the lifting mechanism is arranged in the center of the top of the N-shaped fixing frame, the bottom of the lifting mechanism is connected with the heating and heat preservation mechanism, the fan is arranged on the lower surface of the top of the N-shaped fixing frame, and the conveying mechanism is arranged above the bottom of the N-shaped fixing frame. The utilization rate of heat energy is increased by transmitting high-temperature flue gas in the quenching cavity into the preheating cavity for reutilization, and the problems that the surface of a wire rod is prone to being damaged and the forming strength and bearing capacity of the screw rod are affected due to cold drawing reducing before forming of an existing screw rod, the surface of a hot drawing reducing wire rod is prone to being oxidized, and the material yield is low due to the fact that follow-up acid pickling is needed are solved.

Description

[Technical field]

[0001] The invention relates to the technical field of bolt processing, in particular to the technical field of a tower crane screw production process. [Background technology]

[0002] Tower crane is the most commonly used lifting equipment on construction sites, also known as "tower crane". Among construction machinery, it generally refers to a full-return rolling arm crane with a tower-type structure. It is a common means of transportation on large civil engineering construction sites. It is mainly used for horizontal or vertical lifting of construction materials such as steel bars, wooden slats, concrete, steel pipes, etc. It is an indispensable equipment on the construction site.

[0003] When working at high altitude, tower cranes often transport different types of heavy objects, which places high demands on the stability of the operation, especially for fastening screws, which are required to have high strength, high load-bearing capacity and other performance characteristics to ensure the safety of tower crane operations. However, the existing screws directly use fixed dies and dry powder lubrication to cold-draw and reduce the diameter of the wires before forming, which can easily cause surface damage to the wires, cracks, dents, etc., which affect the strength and load-bearing capacity of the screw forming. If hot-drawing and reducing the diameter of the wires is used, the surface of the wires is easily oxidized, and the subsequent pickling is required, which can easily lead to a low material yield. [Summary of the invention]

[0004] The purpose of the present invention is to solve the problems in the prior art and to propose a tower crane screw production process, which aims to solve the problem that the existing screw directly cold-draws and reduces the diameter of the wire through a fixed die and dry powder lubrication before forming, which easily causes surface damage to the wire and affects the strength and bearing capacity of the screw forming. If hot drawing and diameter reduction are used, the surface of the wire is easily oxidized, and subsequent pickling is required, which easily leads to a low material yield.

[0005] To achieve the above object, the present invention proposes a tower crane screw production process, the steps of the tower crane screw production process include:

[0006] a) Pickling of wire: Immerse the wire in a 20% hydrochloric acid tank at room temperature for 15 minutes and then take it out to remove the oxide film on the wire surface;

[0007] b) Wire annealing: The pickled wire is placed in a vacuum annealing furnace, heated to 750°C and kept at this temperature for 200 minutes, then cooled to 550°C and taken out of the furnace to obtain cold drawn wire for tower crane bolts;

[0008] c) Wire drawing: Place the annealed wire on the wire drawing machine, select the corresponding wire drawing die, draw it to the required wire diameter, and then add lubricant for lubrication and cooling;

[0009] d) Screw forming: the wire rod after drawing is put into the cold heading machine for processing and forging to form the semi-finished tower crane screw rod;

[0010] e) Screw thread rolling: Put the semi-finished tower crane bolts that have completed heat treatment into a thread rolling machine to achieve the required thread to form the finished tower crane bolts;

[0011] f) Screw heat treatment: put the semi-finished tower crane bolts after thread rolling into a quenching device for quenching and heat preservation at 880℃ for 70 minutes, then cool it down, then put it into a tempering device for tempering and heat preservation at 500℃ for 100 minutes, then cool it down to obtain the tower crane bolts.

[0012] Preferably, a multi-pass vacuum annealing process is used in step b, and a multi-pass rotary forging roller die diameter reducing cold drawing process is used in step c. Combining the multi-pass vacuum annealing process with the multi-pass rotary forging roller die diameter reducing cold drawing process can effectively improve the axial elongation and stretching rate of the material.

[0013] Preferably, in step c, anti-wear hydraulic oil is used as lubricant instead of wire drawing powder for lubrication and cooling, so that the surface of the wire is free of burrs, pits, scratches and cracks, thereby improving the molding quality of the screw.

[0014] Preferably, the quenching equipment in step f comprises an N-shaped fixed frame, a lifting mechanism, a heating and heat preservation mechanism, a conveying mechanism and a fan, a lifting mechanism is arranged at the top center of the N-shaped fixed frame, a fan is arranged on the lower surface of the top of the N-shaped fixed frame, the fan is located on the right side of the lifting mechanism, and the lower end of the fan is located below the lower end of the lifting mechanism, a conveying mechanism is arranged above the bottom of the N-shaped fixed frame, a heating and heat preservation mechanism is connected to the bottom of the lifting mechanism, and the bottom of the heating and heat preservation mechanism is against the conveying mechanism.

[0015] Preferably, the N-shaped fixing frame is a side N-shape, and the N-shaped fixing frame includes an upper cross bar, a vertical bar and a lower cross bar. The upper end of the vertical bar is connected to the upper cross bar, and the lower end of the vertical bar is connected to the lower cross bar to form an N-shaped fixing frame. The lifting mechanism includes a lifting cylinder and a lifting rod. The lifting cylinder is located in the middle above the upper cross bar. The lifting rod passes through the upper cross bar and is connected to the lifting cylinder. The lower end of the lifting rod protrudes from the bottom of the lifting rod. The structure is reasonable and simple, and it is easy to install and maintain. It is connected with the heating and insulation mechanism to facilitate the lifting of the heating and insulation mechanism and improve production efficiency.

[0016] Preferably, the heating and heat preservation mechanism comprises a heating partition cover, a heat preservation and insulation layer, a flue gas duct, a temperature control device, a heating device and a preheating chamber door. The heating partition cover contains a preheating chamber, a heating chamber and a quenching chamber. A flue gas duct is arranged between the preheating chamber and the quenching chamber. A temperature control device is arranged at one end of the top of the outer surface of the preheating chamber, the heating chamber and the quenching chamber. A heating device is arranged in the middle of the inner wall of the preheating chamber, the heating chamber and the quenching chamber. The heating chamber and the quenching chamber are both in a closed state. The preheating chamber is provided with a preheating chamber door. A handle is arranged in the middle of the outer surface of the preheating chamber door. The inner wall of the heating partition cover is provided with a heat preservation and insulation layer. The arrangement of the heat preservation and insulation layer can reduce the loss of heat energy. The flue gas duct can transmit the high-temperature flue gas in the quenching chamber to the preheating chamber to preheat the screw in the preheating chamber, thereby improving the utilization rate of heat energy.

[0017] Preferably, the conveying mechanism includes a conveyor belt, an electric roller and an electric roller drive control device. The conveyor belt is arranged on the upper surface of the lower cross bar in the N-shaped fixed frame. A plurality of electric rollers are arranged on the inner surfaces of both ends of the conveyor belt. The electric roller drive control device is arranged on the outer surface of the lower cross bar in the N-shaped fixed frame. The conveyor belt can realize the self-movement of the bolts, thereby improving production efficiency, reducing labor costs and preventing people from being burned.

[0018] The beneficial effects of the present invention are as follows: compared with the prior art, the tower crane screw production process of the present invention has a reasonable and simple structure. By combining a multi-pass vacuum annealing process with a multi-pass rotary forging roller die diameter reduction cold drawing process, the axial elongation and stretching rate of the material are effectively improved. By using anti-wear hydraulic oil instead of wire drawing powder as a lubricant for lubrication and cooling, the surface of the wire can be made smooth and wear-free, thereby improving the forming quality of the screw. A flue gas duct is arranged in the quenching equipment to transmit the high-temperature flue gas in the quenching chamber to the preheating chamber to preheat the tower crane bolts, thereby improving the utilization rate of thermal energy and reducing the consumption of thermal energy. The problem that the existing screw directly cold-draws and reduces the diameter of the wire through a fixed die and dry powder lubrication before forming easily causes damage to the wire surface and affects the strength and bearing capacity of the screw forming. If hot drawing and diameter reduction are used, the surface of the wire is easily oxidized and subsequent pickling is required, which easily leads to a low material yield.

[0019] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0020] Figure 1 The present invention is a schematic diagram of the structure of a quenching device for a tower crane screw production process.

[0021] Figure 2 The invention discloses a schematic structural diagram of an N-shaped fixing frame, a lifting mechanism, a conveying mechanism and a fan in a quenching device in a tower crane screw production process.

[0022] Figure 3 The invention discloses a structural schematic diagram of a heating and heat preservation mechanism in a quenching device of a tower crane screw production process.

[0023] In the figure: 1-N-shaped fixing frame, 2-lifting mechanism, 3-heating and heat preservation mechanism, 4-transmission mechanism, 5-fan, 11-upper cross bar, 12-vertical bar, 13-lower cross bar, 21-lifting cylinder, 22-lifting rod, 31-heating partition cover, 32-heating insulation layer, 33-smoke duct, 34-temperature control device, 35-heating device, 36-preheating chamber door, 41-conveyor belt, 42-electric roller, 43-, electric roller drive control device 311-preheating chamber, 312-heating chamber, 313-quenching chamber. [Specific implementation method]

[0024] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0025] The present invention provides a tower crane screw production process, the steps of the tower crane screw production process include:

[0026] a) Pickling of wire: Immerse the wire in a 20% hydrochloric acid tank at room temperature for 15 minutes and then take it out to remove the oxide film on the wire surface;

[0027] b) Wire annealing: The pickled wire is placed in a vacuum annealing furnace, heated to 750°C and kept at this temperature for 200 minutes, then cooled to 550°C and taken out of the furnace to obtain cold drawn wire for tower crane bolts;

[0028] c) Wire drawing: Place the annealed wire on the wire drawing machine, select the corresponding wire drawing die, draw it to the required wire diameter, and then add lubricant for lubrication and cooling;

[0029] d) Screw forming: the wire rod after drawing is put into the cold heading machine for processing and forging to form the semi-finished tower crane screw rod;

[0030] e) Screw thread rolling: Put the semi-finished tower crane bolts that have completed heat treatment into a thread rolling machine to achieve the required thread to form the finished tower crane bolts;

[0031] f) Screw heat treatment: put the semi-finished tower crane bolts after thread rolling into a quenching device for quenching and heat preservation at 880℃ for 70 minutes, then cool it down, then put it into a tempering device for tempering and heat preservation at 500℃ for 100 minutes, then cool it down to obtain the tower crane bolts.

[0032] See also Figure 1The quenching equipment in step f of a tower crane screw production process of the present invention comprises an N-shaped fixing frame 1, a lifting mechanism 2, a heating and heat preservation mechanism 3, a conveying mechanism 4 and a fan 5. The lifting mechanism 2 is arranged at the top center of the N-shaped fixing frame 1, and the fan 5 is arranged on the lower surface of the top of the N-shaped fixing frame 1. The fan 5 is located on the right side of the lifting mechanism 2, and the lower end of the fan 5 is located below the lower end of the lifting mechanism 2. The conveying mechanism 4 is arranged above the bottom of the N-shaped fixing frame 1, and the heating and heat preservation mechanism 3 is connected to the bottom of the lifting mechanism 2, and the bottom of the heating and heat preservation mechanism 3 is against the conveying mechanism 4.

[0033] See also Figure 2 The N-shaped fixing frame 1 is a side N-shape, and the N-shaped fixing frame 1 includes an upper cross bar 11, a vertical bar 12 and a lower cross bar 13. The upper end of the vertical bar 12 is connected to the upper cross bar 11, and the lower end of the vertical bar 12 is connected to the lower cross bar 13 to form the N-shaped fixing frame 1. The lifting mechanism 2 includes a lifting cylinder 21 and a lifting rod 22. The lifting cylinder 21 is located in the middle above the upper cross bar 11. The lifting rod 22 passes through the upper cross bar 11 and is connected to the lifting cylinder 21. The lower end of the lifting rod 22 protrudes from the bottom of the lifting rod 22. The structure is reasonable and simple, and it is easy to install and maintain. It is connected with the heating and heat preservation mechanism 3 to facilitate the lifting of the heating and heat preservation mechanism 3 and improve production efficiency. The conveying mechanism 4 includes a conveyor belt 41, an electric roller 42 and an electric roller driving control device 43. The conveyor belt 41 is arranged on the upper surface of the lower cross bar 13 in the N-shaped fixed frame 1. A plurality of electric rollers 42 are arranged on the inner surfaces of both ends of the conveyor belt 41. The electric roller driving control device 43 is arranged on the outer surface of the lower cross bar 13 in the N-shaped fixed frame 1. The conveyor belt 41 can realize the self-movement of the bolts, thereby improving production efficiency, reducing labor costs and preventing people from being scalded.

[0034] See also Figure 3The heating and heat preservation mechanism 3 includes a heating partition cover 31, a heat preservation and heat insulation layer 32, a flue gas duct 33, a temperature control device 34, a heating device 35 and a preheating chamber door 36. The heating partition cover 31 contains a preheating chamber 311, a heating chamber 312 and a quenching chamber 313. A flue gas duct 313 is arranged between the preheating chamber 311 and the quenching chamber 313. The top end of the outer surface of the preheating chamber 311, the heating chamber 312 and the quenching chamber 313 is provided with a temperature control device 34. The preheating chamber 311, the heating chamber 312 and the quenching chamber 313 are provided with a temperature control device 34. A heating device 35 is provided in the middle of the inner wall of 313, the heating chamber 312 and the quenching chamber 313 are both in a closed state, the preheating chamber 311 is provided with a preheating chamber door 36, and a handle 36 is provided in the middle of the outer surface of the preheating chamber door 36, and the inner wall of the heating partition cover 31 is provided with a thermal insulation layer 32. The setting of the thermal insulation layer 32 can reduce the loss of heat energy, and the flue gas duct 33 can transmit the high-temperature flue gas in the quenching chamber 313 to the preheating chamber 311 to preheat the screw in the preheating chamber 311, thereby improving the utilization rate of heat energy.

[0035] Working process of the present invention:

[0036] During the working process of the quenching equipment of the tower crane screw production process of the present invention, firstly, the preheating chamber door in the heating and heat preservation mechanism 3 is opened to put the tower crane bolt into the preheating chamber for preheating; after the preheating is completed, the heating partition cover 31 is raised by the lifting cylinder 21, and at the same time, the conveyor belt 41 is driven by the electric roller driving control device 43 to convey the tower crane bolt to the bottom of the heating chamber 312 in the heating partition cover 31, and then the heating partition cover 31 is lowered by the lifting cylinder 21 until it abuts against the conveyor belt 41 to heat the tower crane bolt; after the heating is completed, the heating partition cover 31 is raised by the lifting cylinder 21, and at the same time, the conveyor belt 41 is driven by the electric roller driving control device 43 to convey the tower crane bolt to the bottom of the quenching chamber 313 in the heating partition cover 31, and then the heating partition cover 31 is lowered by the lifting cylinder 21 until it abuts against the conveyor belt 41 to quench the tower crane bolt; after the quenching is completed, the lifting cylinder 21 raises the heating partition cover 31, At the same time, the electric roller driving control device 43 drives the conveyor belt 41 to convey the tower crane bolts to the bottom of the fan 5, and then the tower crane bolts are cooled by the fan to complete the heat treatment of the tower crane bolts. The present invention effectively improves the axial elongation and stretching rate of the material by combining multiple vacuum annealing processes with multiple rotary forging roller die diameter reduction cold drawing processes. By using anti-wear hydraulic oil instead of wire drawing powder as a lubricant for lubrication and cooling, the surface of the wire can be smooth and wear-free, thereby improving the forming quality of the screw. A flue gas duct is arranged in the quenching equipment to transmit the high-temperature flue gas in the quenching chamber to the preheating chamber to preheat the tower crane bolts, thereby improving the utilization rate of thermal energy and reducing the consumption of thermal energy. The problem that the existing screw directly cold-draws and reduces the diameter of the wire through a fixed die and dry powder lubrication before forming easily causes damage to the surface of the wire, affecting the strength and bearing capacity of the screw forming. If hot drawing and diameter reduction are used, the surface of the wire is easily oxidized, and subsequent pickling is required, which easily leads to a low material yield.

[0037] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention belongs to the protection scope of the present invention.

Claims

1. A tower crane screw production process, characterized in that: The steps of the tower crane screw production process include: a) Pickling of wire: Immerse the wire in a 20% hydrochloric acid tank at room temperature for 15 minutes and then take it out to remove the oxide film on the wire surface; b) Wire annealing: The pickled wire is placed in a vacuum annealing furnace, heated to 750°C and kept at this temperature for 200 minutes, then cooled to 550°C and taken out of the furnace to obtain cold drawn wire for tower crane bolts; c) Wire drawing: Place the annealed wire on the wire drawing machine, select the corresponding wire drawing die, draw it to the required wire diameter, and then add lubricant for lubrication and cooling; d) Screw forming: the wire rod after drawing is put into the cold heading machine for processing and forging to form the semi-finished tower crane screw rod; e) Screw thread rolling: Put the semi-finished tower crane bolts that have completed heat treatment into a thread rolling machine to achieve the required thread to form the finished tower crane bolts; f) Screw heat treatment: put the semi-finished tower crane bolts after thread rolling into a quenching device for quenching and heat preservation at 880℃ for 70 minutes, then cool it down, then put it into a tempering device for tempering and heat preservation at 500℃ for 100 minutes, then cool it down to obtain the tower crane bolts.

2. A tower crane screw production process according to claim 1, characterized in that: In the step b, a multi-pass vacuum annealing process is adopted, and in the step c, a multi-pass rotary forging roller die diameter reducing cold drawing process is adopted, and the multi-pass vacuum annealing process and the multi-pass rotary forging roller die diameter reducing cold drawing process are used in combination.

3. A tower crane screw production process according to claim 1, characterized in that: In the step c, anti-wear hydraulic oil is used as lubricant instead of wire drawing powder for lubrication and cooling.

4. A tower crane screw production process according to claim 1, characterized in that: The quenching equipment in step f comprises an N-shaped fixed frame (1), a lifting mechanism (2), a heating and heat preservation mechanism (3), a conveying mechanism (4) and a fan (5), wherein the lifting mechanism (2) is arranged at the top center of the N-shaped fixed frame (1), the fan (5) is arranged on the lower surface of the top of the N-shaped fixed frame (1), the fan (5) is located on the right side of the lifting mechanism (2), and the lower end of the fan (5) is located below the lower end of the lifting mechanism (2), the conveying mechanism (4) is arranged above the bottom of the N-shaped fixed frame (1), the bottom of the lifting mechanism (2) is connected to the heating and heat preservation mechanism (3), and the bottom of the heating and heat preservation mechanism (3) abuts against the conveying mechanism (4).

5. A tower crane screw production process according to claim 4, characterized in that: The N-shaped fixing frame (1) is in a side N-shape, and comprises an upper crossbar (11), a vertical bar (12) and a lower crossbar (13); the upper end of the vertical bar (12) is connected to the upper crossbar (11), and the lower end of the vertical bar (12) is connected to the lower crossbar (13) to form the N-shaped fixing frame (1); the lifting mechanism (2) comprises a lifting cylinder (21) and a lifting rod (22); the lifting cylinder (21) is located in the middle part above the upper crossbar (11); the lifting rod (22) passes through the upper crossbar (11) and is connected to the lifting cylinder (21); and the lower end of the lifting rod (22) protrudes from the bottom of the lifting rod (22).

6. A tower crane screw production process according to claim 4, characterized in that: The heating and heat-insulating mechanism (3) comprises a heating partition cover (31), a heat-insulating layer (32), a flue gas duct (33), a temperature control device (34), a heating device (35) and a preheating chamber door (36); the heating partition cover (31) comprises a preheating chamber (311), a heating chamber (312) and a quenching chamber (313); a flue gas duct (313) is arranged between the preheating chamber (311) and the quenching chamber (313); A temperature control device (34) is provided at one end of the top of the outer surface of each of the preheating chamber (311), the heating chamber (312) and the quenching chamber (313); a heating device (35) is provided at the middle of the inner wall of each of the preheating chamber (311), the heating chamber (312) and the quenching chamber (313); the heating chamber (312) and the quenching chamber (313) are both in a closed state; the preheating chamber (311) is provided with a preheating chamber door (36); a handle (36) is provided at the middle of the outer surface of the preheating chamber door (36); and a thermal insulation layer (32) is provided on the inner wall of the heating partition cover (31).

7. A tower crane screw production process according to claim 4, characterized in that: The conveying mechanism (4) comprises a conveyor belt (41), an electric roller (42) and an electric roller drive control device (43); the conveyor belt (41) is arranged on the upper surface of a lower cross bar (13) in an N-shaped fixed frame (1); a plurality of electric rollers (42) are arranged on the inner surfaces of both ends of the conveyor belt (41); and the electric roller drive control device (43) is arranged on the outer surface of the lower cross bar (13) in the N-shaped fixed frame (1).

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