CN113770290B - Forging method of large-specification high-utilization red copper thin-wall hollow tube - Google Patents

Abstract

The invention relates to a forging method of a large-specification high-utilization red copper thin-wall hollow tube, which comprises a heating stage, a hollow blank manufacturing stage, a preform and wall thickness difference control stage, a sectional drawing and sizing stage, an inverse drawing core rod and drawing stage, a whole body alignment and roundness correction stage and a finishing stage, and the implementation of the technical scheme of the invention mainly comprises the following steps of adopting different tools in different stages, selecting different rolling reduction, rotation angles and feeding amounts, and controlling the external circle size, wall thickness and roundness of the finished product stage to control the external dimension molding of the final product; the method can greatly reduce the production and manufacturing cost, improve the forging and drawing efficiency and reduce waste products.

Description

Forging method of large-specification high-utilization red copper thin-wall hollow tube

Technical Field

The invention belongs to the technical field of forging, and particularly relates to a forging method of a large-specification high-utilization red copper thin-wall hollow tube.

Background

T2 is red copper, has good thermal conductivity and electrical conductivity, has high low-temperature strength, is widely applied to the fields of electric appliances and industry because of good heat dissipation performance for manufacturing large-specification thin-wall T2 tubes, and most of industrial thin-wall red copper tubes (wherein, the large-specification thin-wall tubes refer to hollow tubes with Di being more than or equal to 850mm, do being more than or equal to 1000mm and Do/Di being more than or equal to 1.1 and being less than or equal to 1.4, wherein Do is the outer diameter of the tubes, di is the inner diameter of the tubes), and needs to be completed by forging technologies such as upsetting, punching, reaming, drawing and the like, and because red copper has good ductility, the industrial hollow thin-wall T2 tubes are large in size, the material is widened during transverse drawing and the material is fast in the forging drawing process when Do/Di is less than or equal to 1.4; the longitudinal direction, namely the length direction, is small in stretching quantity, slow in feeding and low in drawing efficiency, meanwhile, the price of the T2 material is high, the general forging utilization rate is as high as more than 94%, the forging efficiency is low, the forging length of a finished product is slightly controlled improperly, and the process requirement is hardly met, so that the product is scrapped, and the cost waste of industrial production is caused.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a forging method of a large-specification high-utilization red copper thin-wall hollow tube, which can avoid large material widening amount and quick feeding of the red copper thin-wall hollow tube during transverse drawing; the longitudinal direction, namely the length direction, has the defects of small stretching amount, slow feeding, low drawing efficiency and scrapping caused by short length, and the method can greatly reduce the production and manufacturing cost, improve the forging drawing efficiency and reduce waste products.

The technical scheme of the invention is realized as follows: a forging method of a large-specification high-utilization red copper thin-wall hollow tube comprises the following forging steps:

step 1), heating stage: firstly, heating a red copper ingot, charging the red copper ingot by adopting a cold ingot, controlling the heating temperature to be 400-500 ℃, preserving heat for 0.5 hour, then heating to 950+/-10 ℃ at the heating rate of less than or equal to 100 ℃/hour, preserving heat for 3-5 hours, and forging;

step 2), a hollow blank manufacturing stage: the copper ingot is subjected to chamfering, drawing and rounding, upsetting, punching and reaming, and finally a hollow blank is manufactured for subsequent drawing;

step 3), preform and control wall thickness difference stage: after reaming is finished, penetrating the hollow blank into the big end of the drawn core rod, firstly drawing the big end for one circle, ensuring that the blank is attached to the surface of the drawn core rod, and facilitating the feeding of metal along the side of the drawn core rod with small taper in the later stage when the drawing is finished; the manipulator is used for holding the holding end of the elongated mandrel, the upper flat anvil and the lower V anvil are pushed and pulled for 2-3 times, the wall thickness is aligned, and the wall thickness difference is controlled to be less than or equal to 20mm; at the moment, do/Di is larger than 1.4, do is the outer diameter of the pipe, di is the inner diameter of the pipe, the wall thickness is larger, the rolling reduction is less than or equal to 1/4 of the wall thickness during pushing and pulling, the rotation angle is firstly pushed and pulled for one pass according to the whole body of 45 degrees, then pushed and pulled for 1 pass according to the rotation angle of 22.5 degrees, the wall thickness difference is controlled, the wall thickness is ensured to be uniform, the vertical material is upset before returning to the furnace for heating, the two end faces are flattened, and the end inclined surfaces and the horseshoe-shaped end faces caused by uneven material feeding are eliminated;

step 4), stage of sectional drawing and sizing: the anvil is replaced by an upper V-shaped anvil and a lower V-shaped anvil with 135-degree openings, and the transverse stretching of the blank can be effectively controlled by using the upper V-shaped anvil and the lower V-shaped anvil for drawing, so that the drawing efficiency is improved; according to the push-pull sequence of 1 ～ 2 ～ 3 ～ 4 ～ 5, the weight is pushed and pulled to the wall thickness less than or equal to 1/3, the blank reaches 50-60% of the total process length, the blank is fed according to the anvil width less than or equal to 1/3, the rotation angle is pushed and pulled for 1 pass according to 90 degrees, then according to 45 degrees, finally, the outer diameter of the last pass is directly reduced by 25-30mm according to the required process size, the forging outer diameter is controlled, the same roundness of any section is greatly different, the bulge is locally obvious, the process does not need to excessively control the same roundness, only the wall thickness difference and the excircle size are controlled, and then the outer diameter of the nominal process size reduced by 25-30mm is set as the target standard size;

step 5), reversely threading and drawing the core rod and drawing the other section: after reversely penetrating the blank into the drawn core rod, the blank is also formed by adopting a push-pull mode, and the hammering amount is directly forged according to the target standard size set in the step 4), namely, the nominal size of the process is reduced by 25-30mm, the rotation angle is firstly pushed and pulled by one pass according to 90 degrees, and then pushed and pulled by one pass according to 45 degrees;

step 6), general alignment and roundness and finishing to a finished product stage: the mandrel is inserted and drawn in the forward direction, the mandrel is formed by pushing and pulling, the lower hammer weight is not required, the size of the forging excircle of the hammer is directly set to be the target standard size just, and the forging excircle is added with 25-30mm, namely, the diameter of the excircle is set to be forged according to the nominal size of the process; the rotation angles are respectively 45-22.5-11.25-6 degrees, the feeding amount is less than or equal to 1/2 anvil width, and each angle is finished with one pass of excircle, so that the finished product can be obtained by forging.

In the step 2), the blank is elongated and rounded to a height-diameter ratio of 1.8-2.2 before upsetting, then upsetting is carried out, and the height-diameter ratio of the upset blank reaches 0.65-0.7 and the upsetting is stopped; then selecting a phi 380 solid punch for punching, placing the upset solid blank on a platform, placing the phi 380 solid punch at the right center of the solid blank, starting to punch positively, calculating the thickness of a punching core through the height of the solid blank and the height of the punch, controlling the thickness of the punching core to be less than or equal to 80mm due to high material utilization rate, and then punching reversely; if the height of one punch is insufficient in the forward punching process, an auxiliary solid punch smaller than phi 380 is continuously added on the phi 380 punch, and the punch is continuously carried out; when the material core thickness reaches a target value during forward punching, reversely punching, punching the material core, namely turning over the blank for 180 degrees, filling a hollow drain pan on the lower surface of the blank, punching the material core by using a phi 380 solid punch at the right center of the other surface of the solid blank, and punching the material core; when the beam is used for reaming, the reaming diameter is 20-50 mm larger than the diameter of the small end of the drawing core rod; the whole forging and drawing process is carried out, and the temperature range is controlled to be 350-850 ℃.

The invention has the following beneficial effects: during mass production, the forging and drawing efficiency is high, standardized operation is convenient, the risks of short forging length and short length of finished products due to high utilization rate and thin wall thickness are effectively avoided, and the production cost is reduced.

Drawings

Fig. 1 is a schematic diagram of a heating process of the copper ingot according to the present invention.

Fig. 2 is a schematic view of the step 2 forward punching of the present invention.

Fig. 3 is a schematic view of the step 2 reverse punching of the present invention.

Fig. 4 is a schematic view of the hollow blank after the end face is flattened in the step 3 of the present invention.

Fig. 5 is a schematic view of an elongated mandrel used in accordance with the present invention.

Fig. 6 is a schematic view of the step blank of step 4 of the present invention.

FIG. 7 is a schematic view of the step billet of the step 5 of the present invention.

Fig. 8 is a schematic diagram of the roundness of the blank in step 4 and step 5 of the present invention.

Fig. 9 is a diagram of the finished forging stock of the present invention.

In the description of the drawings, 1: an auxiliary solid punch; 2: a solid blank; 3: phi 380 solid punch; 4: a hollow drain pan.

Detailed Description

The implementation of the technical scheme of the invention mainly comprises a forging method for controlling the appearance size molding of a final product by adopting different tools at different stages, selecting different rolling reduction, rotation angles and feeding amounts, controlling the outer circle size and wall thickness at the final product stage and controlling the same roundness.

A forging method of a large-size high-utilization red copper thin-wall tube comprises the following specific steps:

step 1), heating stage: and heating the red copper ingot (also called as T2 red copper ingot), charging the red copper ingot by adopting a cold ingot heating process, wherein the heating temperature is 400-500 ℃, preserving heat for 0.5 hour, then heating to 950+/-10 ℃ at the heating rate of less than or equal to 100 ℃/hour, preserving heat for 3-5 hours, and forging.

Step 2), a hollow blank manufacturing stage: the red copper ingot 2 (also called solid blank 2) is subjected to chamfering, drawing and rounding, upsetting, punching and reaming to finally prepare a hollow blank (shown in fig. 4) for subsequent drawing.

It is emphasized that: before upsetting, drawing and rounding the solid blank 2 to a height-diameter ratio of 1.8-2.2, upsetting, and stopping upsetting when the height-diameter ratio of the solid blank 2 after upsetting reaches 0.65-0.7; then selecting a phi 380 solid punch 3 for punching, placing the upsetted solid blank 2 on a platform, placing the phi 380 solid punch 3 at the right center of the solid blank 2, starting to punch positively (as shown in figure 2), calculating the thickness of a punching core through the height of the solid blank 2 and the heights of the phi 380 solid punch 3 and the auxiliary solid punch 1, controlling the thickness of the punching core to be less than or equal to 80mm because of high material utilization rate, and then punching reversely as shown in figure 3, if the height of the phi 380 solid punch 3 is insufficient during positive punching, continuously adding an auxiliary solid punch 1 smaller than the phi 380 on the phi 380 solid punch 3, and continuously punching; after the calculated core thickness reaches the target value during forward punching, the core is punched in the reverse direction as shown in fig. 3, namely: turning the blank for 180 degrees, filling a hollow drain pan 4 on the lower surface of the blank, and punching the center of the other surface of the solid blank 2 by using a phi 380 solid punch 3 to punch off the material center; when the beam is used for reaming, the reaming diameter is 20-50 mm larger than the diameter of the small end of the drawing core rod; the whole forging and drawing process is carried out at the temperature of 350-850 ℃.

Step 3), a preform and a wall thickness difference control stage; after reaming is finished, penetrating the drawing core rod, penetrating a hollow blank (shown in fig. 4) into the big end of the drawing core rod, firstly drawing the big end for one circle, ensuring that the blank is attached to the surface of the core rod, and facilitating the later pushing and pulling of metal along the side with small taper of the drawing core rod. The manipulator is used for holding and pulling the holding end of the core rod, the upper flat anvil and the lower V anvil are used for pushing and pulling for 2-3 times, the wall thickness is aligned, the wall thickness difference is controlled to be less than or equal to 20mm, at the moment, do/Di is more than 1.4, the wall thickness is larger, the reduction is less than or equal to 1/4 wall thickness when pushing and pulling, the rotation angle firstly pushes and pulling for one pass according to 45 degrees, then pushes and pulls for 1 pass according to 22.5 degrees, the wall thickness difference is controlled, the wall thickness is ensured to be uniform, the upsetting of the vertical materials is ensured, the two end faces are flattened, and the end inclined surfaces and the horseshoe-shaped end faces caused by uneven feeding are eliminated.

Step 4), stage of sectional drawing and sizing: the anvil is replaced by an upper V-shaped anvil and a lower V-shaped anvil with 135-degree openings, and the transverse stretching of the blank can be effectively controlled by using the upper V-shaped anvil and the lower V-shaped anvil for drawing, so that the drawing efficiency is improved; according to the sequence of drawing (1 ～ 2 ～ 3 ～ 4 ～ 5), the weight is reduced by less than or equal to 1/3 wall thickness, firstly drawing is carried out until the blank reaches about 50-60% of the total process length, feeding is carried out according to less than or equal to 1/3 anvil width, the rotation angle is firstly carried out according to 90 degrees, then carrying out drawing according to 45 degrees, finally carrying out drawing for 1 pass according to 22.5 degrees, the outer diameter size of the last pass is directly reduced by 25-30mm according to the required nominal process size, at the moment, the same roundness of any section is greatly different (figure 8), the bulge is locally obvious, the process does not need excessive control of the same roundness, only the wall thickness difference and the excircle size are controlled, then the outer diameter size of the nominal process size is reduced by 25-30mm is set to be the target reference size, the forging is different from other thick-wall tubes, the forging of the excircle size is not caused to be small, because the thin-wall tube is drawn to be in the final product stage, the metal mobility in the length direction is poor, the length widening amount is small, the metal transverse widening flow is fast according to the minimum resistance law, and therefore, the diameter is easy to control and the length control difficulty is great.

Step 5), reversely threading and drawing the core rod and drawing the other section: as shown in fig. 7, after the blank is reversely penetrated into the drawn mandrel (in order to eliminate or reduce the occupation of the taper of the inner hole and reduce the weight of the tube), the blank is also formed by push-pull, and the lower hammer is directly forged according to the target standard size set in the step 4) (namely, the nominal process size is reduced by 25-30 mm), and the rotation angle is pushed by 90 degrees for one pass and then pushed by 45 degrees for one pass.

Step 6), general alignment and roundness and finishing to a finished product: the mandrel is inserted and drawn in the forward direction, the mandrel is formed by pushing and pulling, the lower hammer weight is not required, the size of the forging outer circle of the hammer is directly set to be the just target standard size, and 25-30mm is added (namely, the diameter of the outer circle is set to be forged according to the nominal size of the process); the rotation angles are respectively 45-22.5-11.25-6 degrees, the feeding amount is less than or equal to 1/2 anvil width, and each angle is used for finishing the outer circle for 1 pass; the forging can be carried out to a finished product, and the measured excircle, the measured inner hole and the measured wall thickness meet the process requirements.

Forging example 1:

flat square T2 red copper ingot with the ingot number of T220721D09 and the specification of 2230, 500 and 1000, and the weight of the ingot is 10000kg; planning forging specifications: the excircle phi 1060+/-10; inner hole phi 910 plus or minus 20, length 4650 plus or minus 20; the weight of the forging stock is 9670kg, and the forging utilization rate is 96.7%; the forging comprises the following specific steps:

step 1), heating a T2 red copper ingot: the heating process adopts cold ingot furnace charging, heat preservation for 0.5 hours at 400-500 ℃, then heating to 950+/-10 ℃ at the heating rate of less than or equal to 100 ℃/hour, heat preservation for 3 hours and forging.

Step 2), punching a T2 red copper ingot by using a conventional steel ingot chamfering, rounding and upsetting H=850 (the diameter of a solid blank is phi 1280), using a phi 380 punch, and reaming by using a beam until the thickness of a punching core is 50mm, wherein the diameter of the punching core is increased to phi 910+/-10.

Step 3), preform and control wall thickness difference stage: after reaming is finished, penetrating into a phi 900 drawing core rod (drawing core rod length 4500, large end phi 900, small end phi 855, taper 1:100), penetrating a blank into the large end of the drawing core rod, firstly drawing the large end for one circle, facilitating the feeding of later metal along the taper of the core rod, adding the holding end of the drawing core rod by an operator, pushing and pulling for 3 times by adopting an upper flat anvil and a lower V anvil according to the hammer head pushing and pulling sequence shown in a figure six, pushing and pulling for one time by rotating angles according to 45-22.5-11.25 degrees respectively, wherein the rolling reduction of each time is less than or equal to 1/3 wall thickness, the feeding of a half anvil, the wall thickness alignment and the wall thickness difference control are less than or equal to 20mm; at the moment, the excircle is drawn to be about phi 1250 (inner hole phi 910) in length to 1900; before the furnace is returned for heating, the two end faces are flattened by the vertical material, and the end inclined plane caused by uneven material feeding is eliminated, so that the utilization rate is maximized.

Step 4), a stage of sectional sizing: the anvil is replaced by a 700 upper V anvil and a 700 lower V anvil with 135-degree openings, at the moment, do/Di is less than or equal to 1.4, and the transverse stretching of the blank can be effectively controlled by using the upper and lower V anvils for drawing, so that the drawing efficiency is improved; according to the sequence of drawing (1 ～ 2 ～ 3 ～ 4 ～ 5), the weight of the hammer is less than or equal to 1/3 of the wall thickness, the hammer is fed according to the width of the anvil which is less than or equal to 1/3 of the wall thickness, the rotation angles are respectively drawn for 1 pass according to 90 degrees to 45 degrees to 22.5 degrees, the total length of the blank is firstly drawn to 2300 to 2800mm, the outer diameter size is set according to phi 1035mm (the process outer diameter phi 1060 mm), the same roundness of any section is greatly different, the local bulge is obvious, the process does not need to excessively control the same roundness, only the wall thickness difference and the outer circle size are controlled, and the phi 1035mm is set as the target reference size. (explaining: different from other thick-wall tube forging, the dimension forging is avoided being small, the final product stage of thin-wall tube drawing is avoided, according to the law of minimum resistance, the length-direction metal flow difference length broadening is small, the metal transverse broadening flow is fast, therefore, the diameter is well controlled, and the length direction is not easy to control); the blank size of this section is about Φ1035-1500.

Step 5), reversely threading and drawing the core rod and drawing the other section: after the blank is reversely penetrated into the drawing core rod (the purpose is to eliminate or reduce the occupation of the taper of an inner hole and reduce the weight of a pipe), as shown in fig. 7, the drawing is also performed, at this time, the drawing diameter is forged according to the target reference dimension phi 1035 set in the step four, the drawing is performed for one pass according to the rotation angle of 90 degrees, and then the drawing is performed for one pass according to the 45 degrees;

step 6), general alignment and roundness and finishing to a finished product stage: the core rod is inserted and drawn in the forward direction, the push-pull forming is carried out, the lower hammer quantity is not required, at the moment, the forging excircle size of the hammer head is set to be the nominal process size, namely, the core rod is drawn according to phi 1060 mm; the rotation angles are respectively pushed and pulled for one pass according to 45 degrees to 22.5 degrees to 11.25 degrees to 6 degrees, the feeding amount is less than or equal to 1/2 anvil width, the excircle is finished, the purpose of eliminating the local bulging is achieved, the same roundness is corrected, and the excircle size and length are ensured to meet the technological requirements; at this time, measuring the outer circle phi 1060, the inner hole phi 905 and the wall thickness difference of 5-8mm and the length 4700 of the pipe; all meet the process requirements.

Claims (2)

1. A forging method of a large-size high-utilization red copper thin-wall hollow tube is characterized by comprising the following steps of: the method comprises the following forging steps: step 1), heating stage: firstly, heating a red copper ingot, charging the red copper ingot by adopting a cold ingot, controlling the heating temperature to be 400-500 ℃, preserving heat for 0.5 hour, then heating to 950+/-10 ℃ at the heating rate of less than or equal to 100 ℃/hour, preserving heat for 3-5 hours, and forging; step 2), a hollow blank manufacturing stage: the copper ingot is subjected to chamfering, drawing and rounding, upsetting, punching and reaming, and finally a hollow blank is manufactured for subsequent drawing; step 3), preform and control wall thickness difference stage: after reaming is finished, penetrating the hollow blank into the big end of the drawn core rod, firstly drawing the big end for one circle, ensuring that the blank is attached to the surface of the drawn core rod, and facilitating the feeding of metal along the side of the drawn core rod with small taper in the later stage when the drawing is finished; the manipulator is used for holding the holding end of the elongated mandrel, the upper flat anvil and the lower V anvil are pushed and pulled for 2-3 times, the wall thickness is aligned, and the wall thickness difference is controlled to be less than or equal to 20mm; at the moment, do/Di is larger than 1.4, do is the outer diameter of the pipe, di is the inner diameter of the pipe, the rolling reduction is less than or equal to 1/4 wall thickness during pushing and pulling, the rotation angle is firstly pushed and pulled for one pass according to 45 degrees, then pushed and pulled for 1 pass according to 22.5 degrees, the wall thickness difference is well controlled, the wall thickness is ensured to be uniform, the vertical material upsetting is carried out before the furnace returning and heating, the two end faces are flattened, and the end inclined surfaces and the horseshoe-shaped end faces caused by uneven material feeding are eliminated; step 4), stage of sectional drawing and sizing: the anvil is replaced by an upper V-shaped anvil and a lower V-shaped anvil with 135-degree openings, and the transverse stretching of the blank can be effectively controlled by using the upper V-shaped anvil and the lower V-shaped anvil for drawing, so that the drawing efficiency is improved; according to the push-pull sequence of 1 ～ 2 ～ 3 ～ 4 ～ 5, the weight is pushed and pulled to the wall thickness less than or equal to 1/3, the blank reaches 50-60% of the total process length, the blank is fed according to the anvil width less than or equal to 1/3, the rotation angle is pushed and pulled for 1 pass according to 90 degrees, then according to 45 degrees, finally, the outer diameter of the last pass is directly reduced by 25-30mm according to the process size required by the forging process, the forging outer diameter is controlled, at the moment, the same roundness of any section is greatly different, the bulge is locally obvious, the process does not need to excessively control the same roundness, only the wall thickness difference and the excircle size are controlled, and then the outer diameter required by the forging process is reduced by 25-30mm is set as the target standard size; step 5), reversely threading and drawing the core rod and drawing the other section: after reversely penetrating the blank into the drawn core rod, the blank is also formed by push-pull, and the hammering amount is directly forged according to the target standard size set in the step 4), namely, the forging process is reduced in process size by 25-30mm, the rotation angle is firstly pushed and pulled by 90 degrees for one pass, and then pushed and pulled by 45 degrees for one pass; step 6), general alignment and roundness and finishing to a finished product stage: the mandrel is inserted and drawn in the forward direction, the mandrel is formed by pushing and pulling, the lower hammer weight is not required, the size of the forging excircle of the hammer is directly set to be the target standard size just, and the forging is performed by adding 25-30mm, namely, the diameter of the excircle is set to be the process size according to the forging process requirement; the rotation angles are respectively 45-22.5-11.25-6 degrees, the feeding amount is less than or equal to 1/2 anvil width, and each angle is finished with one pass of excircle, so that the finished product can be obtained by forging.

2. The forging method of the large-specification high-utilization red copper thin-wall hollow tube according to claim 1, which is characterized by comprising the following steps: in the step 2), the blank is elongated and rounded to a height-diameter ratio of 1.8-2.2 before upsetting, then upsetting is carried out, and the height-diameter ratio of the upset blank reaches 0.65-0.7 and the upsetting is stopped; then selecting a phi 380 solid punch for punching, placing the upset solid blank on a platform, placing the phi 380 solid punch at the right center of the solid blank, starting to punch positively, calculating the thickness of a punching core through the height of the solid blank and the height of the punch, controlling the thickness of the punching core to be less than or equal to 80mm due to high material utilization rate, and then punching reversely; if the height of one punch is insufficient in the forward punching process, an auxiliary solid punch smaller than phi 380 is continuously added on the phi 380 punch, and the punch is continuously carried out; when the material core thickness reaches a target value during forward punching, reversely punching, punching the material core, namely turning over the blank for 180 degrees, filling a hollow drain pan on the lower surface of the blank, punching the material core by using a phi 380 solid punch at the right center of the other surface of the solid blank, and punching the material core; when the beam is used for reaming, the reaming diameter is 20-50 mm larger than the diameter of the small end of the drawing core rod; the whole forging and drawing process is carried out, and the temperature range is controlled to be 350-850 ℃.

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