CN110576089B - Particle filler assisted push-bending forming method for large-caliber small-bending-radius thin-wall bent pipe - Google Patents
Particle filler assisted push-bending forming method for large-caliber small-bending-radius thin-wall bent pipe Download PDFInfo
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- CN110576089B CN110576089B CN201910716300.2A CN201910716300A CN110576089B CN 110576089 B CN110576089 B CN 110576089B CN 201910716300 A CN201910716300 A CN 201910716300A CN 110576089 B CN110576089 B CN 110576089B
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- 238000005452 bending Methods 0.000 title claims abstract description 146
- 239000000945 filler Substances 0.000 title claims abstract description 62
- 239000002245 particle Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000007906 compression Methods 0.000 claims abstract description 6
- 230000009471 action Effects 0.000 claims abstract description 5
- 230000006835 compression Effects 0.000 claims abstract description 5
- 229920002635 polyurethane Polymers 0.000 claims description 31
- 239000004814 polyurethane Substances 0.000 claims description 31
- 239000004677 Nylon Substances 0.000 claims description 26
- 229920001778 nylon Polymers 0.000 claims description 26
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000000919 ceramic Substances 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 229920003023 plastic Polymers 0.000 claims description 2
- 239000004033 plastic Substances 0.000 claims description 2
- 238000005336 cracking Methods 0.000 abstract description 3
- 230000007547 defect Effects 0.000 abstract description 3
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- 238000005516 engineering process Methods 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 235000015842 Hesperis Nutrition 0.000 description 1
- 235000012633 Iberis amara Nutrition 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
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- 230000007797 corrosion Effects 0.000 description 1
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- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000013000 roll bending Methods 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D9/00—Bending tubes using mandrels or the like
- B21D9/12—Bending tubes using mandrels or the like by pushing over a curved mandrel; by pushing through a curved die
- B21D9/125—Bending tubes using mandrels or the like by pushing over a curved mandrel; by pushing through a curved die by pushing through a curved die
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D9/00—Bending tubes using mandrels or the like
- B21D9/15—Bending tubes using mandrels or the like using filling material of indefinite shape, e.g. sand, plastic material
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Bending Of Plates, Rods, And Pipes (AREA)
Abstract
The invention relates to the technical field of pipe bending forming, in particular to a particle filler assisted large-caliber small-bending-radius thin-wall bent pipe bending forming method. The method realizes bending by using a push head to push the pipe along the flowing deformation of a die, realizes internal pressure support by adopting particle filler compression, realizes internal pressure control by adopting pressure maintaining punch feeding at two sides, and adjusts the stress state of the pipe during bending by controlling the axial force of the push head to push the pipe and the pressure of the particle filler in real time so as to further achieve the action of controlling deformation. The method can push, bend and form the large-caliber small-bending-radius thin-wall pipe elbow with the straight line segment by controlling the internal pressure of the particle filler. Therefore, the bending forming device is suitable for forming the large-caliber small-bending-radius thin-wall bent pipe, and simultaneously well overcomes the bending forming defects of the ultra-thin-wall pipe such as outer side wall stretch cracking, inner side wall wrinkling, oval distortion of cross section, uneven wall thickness and the like.
Description
Technical Field
The invention relates to the technical field of pipe bending forming, in particular to a particle filler assisted large-caliber small-bending-radius thin-wall bent pipe bending forming method.
Background
The tubular member has a hollow section, is suitable for being used as a carrier for conveying materials, has the properties of light weight, high toughness, low consumption, high efficiency and the like, and is provided with a large number of guide pipes with large calibers, small relative wall thicknesses and small relative bending in pipeline systems of aerospace engines and carrier rockets. Because the requirements of the devices on light weight and reliability are higher and higher, many bent pipes require seamless and ultrathin walls (the relative wall thickness, namely the ratio of the thickness to the outer diameter of the pipe, is less than or equal to 0.005) and small bending radii (the relative bending radius, namely the bending radius/the outer diameter of the pipe, is less than or equal to 2), the traditional bending method is difficult to obtain qualified products, and the splicing welding method is mainly adopted in engineering. However, the welding deformation not only affects the dimensional accuracy of the conduit, but also reduces the working accuracy, fatigue resistance and corrosion resistance of the conduit, and the integral elbow without the welding seam is urgently required.
A great deal of research work is done at home and abroad aiming at the pipe bending technology, a series of pipe bending technologies are developed, and the bending technology of the pipe mainly comprises bending by winding, bending by pressing, bending by pulling, roll bending, push bending and the like. Of these bending methods, numerical control bending, internal pressure push bending and liquid filled press bending are several bending methods that can be used to form smaller relative bend radii.
(1) Numerical control bending: the numerical control bending technology is widely applied to actual production, the numerical control bending can continuously form the pipe on a three-dimensional space at one time, the numerical control bending with a core rod can bend the pipe with a relative bending radius of more than 1.5, and the numerical control bending technology with other structures for reducing defects, such as anti-crease blocks and the like can also bend the pipe with a relative bending radius of 1.2.
(2) Liquid-filled press bending: the liquid-filled press bending technology for filling liquid medium in a sealed pipe blank adopts the liquid pressure support which is uniformly distributed, and then the pressure of the liquid in the bent pipe is increased to press and bend the pipe in a mould, so that the method has the characteristics of high forming efficiency and good surface quality, can be used for bending and forming high-performance aluminum alloy and high-strength steel materials, and is particularly suitable for bending pipes with variable curvature and large diameter-thickness ratio d/t.
(3) And (3) internal pressing and bending: the internal pressure push bending process is a pipe bending process which is based on push bending forming, fills supporting materials in a pipe blank and generates enough internal pressure to act on a pipe wall by the filling materials. Due to the introduction of the internal pressure effect of the filler, wrinkling can be effectively prevented, and additional pressure stress is caused in the axial direction of the pipe fitting due to the action of pushing force and friction force, so that the bent neutral layer moves towards the outer side, and the reduction of the wall thickness of the outer side is facilitated.
The deformation mechanisms of the three pipe bending methods are tension-compression deformation mechanisms essentially, namely, when the pipe is bent, the material on the outer side of the bending deformation area is stretched by tangential tension, and the material on the inner side is shortened by tangential compression. According to the stress characteristics of the pipe fitting in the deformation process, the main problems in the pipe bending process include buckling at the inner side of the pipe, thinning and even cracking of the outer side wall of the pipe, distortion of the shape of the cross section and resilience after bending deformation. The technical problem is more prominent in bending deformation of the thin-walled tube.
Disclosure of Invention
The invention aims to provide a particle filler assisted push-bending forming method for a large-caliber small-bending-radius thin-wall elbow.
The technical scheme for solving the technical problems is as follows:
a particle filler assisted large-caliber small-bending-radius thin-wall bent pipe bending and forming method includes the steps that a pushing head is used for pushing a pipe to flow along a die to deform so as to achieve bending, particle filler is used for compressing so as to achieve internal pressure support, pressure maintaining punches on two sides are used for feeding so as to achieve internal pressure control, the axial force of the pushing head pushing the pipe and the pressure of the particle filler are controlled in real time so as to adjust the stress state of the pipe during bending, and therefore deformation control is achieved.
The particle filler assisted push-bending forming method for the large-caliber small-bending-radius thin-wall bent pipe comprises the following steps:
step 1: blanking the tube blank and chamfering the inner side of the end part of the tube blank, wherein the blanking length L of the tube blank is more than pi R/2+ L0(ii) a In the formula, R is the radius of an arc line of a central axis of the push-bending die and is in mm; l is0The length sum of straight line segments at two ends of the formed bent pipe is unit mm;
step 2: filling a section of nylon cylindrical rod at the head of the tube blank;
and step 3: putting one end of the tube blank self-bending die into the bending die;
and 4, step 4: putting a core rod with a core print at one end into a polyurethane cylinder, putting the polyurethane cylinder and the core rod into a bending mould together from the other end of the bending mould, and initially placing the polyurethane cylinder and the core print at the bending section of the bending mould;
and 5: filling particle fillers in the tube blank, wherein the filling length of the particle fillers is equal to the length of the bending section of the finally formed bent tube of the tube blank, and filling another section of nylon cylindrical rod at the tail of the tube blank;
step 6: the pushing head and the pressure maintaining punch head push the pipe blank forward to move together, the core rod moves backward passively, a reverse acting force is applied when the core head of the core rod retreats, and after the polyurethane cylinder is completely pushed to a straight line section of the head of the bending die, the pressure is increased through the core rod and the pressure maintaining punch head is stressed to balance and stand still;
and 7: after the tube blank enters a bending section, the core rod is reversely pressurized, and the particle filler is compressed under the action of the core rod and the pressure maintaining punch head to provide supporting force; maintaining the pressure of the pressure maintaining punch and the core rod, wherein the feeding force of the pressure maintaining punch and the core rod is adjusted to control the internal pressure during pressure maintaining, the particle filler is generally fixed in the pressure maintaining stage, and the tube blank flows forwards under the support of the particle filler; the pushing head continues to push the tube blank to move until the tube blank forms a bent tube.
In the particle filler assisted push-bending forming method of the large-caliber small-bending-radius thin-wall elbow, in step 1, a groove of 15-75 degrees is cut in the inner side of one end of a pipe blank.
According to the particle filler assisted push-bending forming method for the large-caliber small-bending-radius thin-wall elbow, in the step 2 and the step 5, the hardness of the nylon cylindrical rod is Shore D80-90, and the diameter of the nylon cylindrical rod is smaller than the inner diameter of the tube blank by 1-3 mm, so that the nylon cylindrical rod and the tube blank form clearance fit.
According to the particle filler assisted large-caliber small-bending-radius thin-wall bent pipe bending forming method, in the step 3, the inner diameter of the bending die is the same as the outer diameter of the pipe blank, and the bending die is in sliding fit with the pipe blank.
According to the particle filler assisted push-bending forming method for the large-caliber small-bending-radius thin-wall elbow, in the step 4, the hardness of the polyurethane cylinder is Shore A40-100, the outer diameter of the polyurethane cylinder is 1-3 mm smaller than the inner diameter of the push-bending die, so that the polyurethane cylinder and the push-bending die form clearance fit, and the inner diameter of the polyurethane cylinder is the same as the inner diameter of the pipe blank.
In the step 4, one end face of a polyurethane cylinder corresponds to and is in top contact with the end face of the head of the tube blank, and the other end of the polyurethane cylinder is positioned on a straight line section of the head of the push-bending die; one end face of the core head corresponds to and is in top contact with the nylon cylindrical rod at the head of the tube blank, and the other end of the core rod extends out of the push bending die.
In the step 5, the material of the particle filler is metal, ceramic or plastic, and the diameter of the particle filler is 0.5 mm-10 mm.
In the step 6, the pressure maintaining punch is arranged in a tubular push head, the push head and the pressure maintaining punch are placed into one end of a push-bending die, one end face of the push head corresponds to and is in abutting contact with the end face of the tail of the tube blank, and one end face of the pressure maintaining punch corresponds to and is in abutting contact with a nylon cylindrical rod at the tail of the tube blank.
The design idea of the invention is as follows:
and the internal pressure support is realized by compressing the granular packing. The method is characterized in that a cylindrical chain-type core rod is adopted, the core rod is passively stressed from an initial stage to a pressure maintaining stage to ensure that the particle filler moves to a die bending section, and the core rod actively applies counter force and a pressure maintaining punch to realize internal pressure control from the pressure maintaining stage to final forming. The stress state of the pipe during bending is adjusted by controlling the axial force of the pushing head pushing pipe and the pressure of the particle filler in real time, so that the deformation behavior is controlled.
The invention has the advantages and beneficial effects that:
1. in the prior art, the feeding force is directly applied to the pipe, the supporting force in the cavity is directly applied to the pipe through the rigid core rod, and the bending deformation of the thin-wall pipe cannot be realized, especially the bending deformation of the pipe with an ultrathin wall (the relative wall thickness, namely the ratio of the thickness to the pipe outer diameter is less than or equal to 0.005) and a small bending radius (the relative bending radius, namely the bending radius/the pipe outer diameter is less than or equal to 2). Because the internal supporting force of the pipe is generated by controlling the particle filler, the bending deformation of the pipe with an ultra-thin wall (the relative wall thickness, namely the ratio of the thickness to the pipe outer diameter is less than or equal to 0.005) and a small bending radius (the relative bending radius, namely the bending radius/the pipe outer diameter is less than or equal to 2) is realized, and the bending part is prepared. The stress state of the pipe during bending is adjusted by controlling the pressure and the axial force of the particle filler in real time, so that the purpose of controlling the deformation behavior is achieved.
2. The bending forming method can process metal and alloy materials such as steel, aluminum, copper and the like, and is particularly suitable for bending pipes with large calibers and small bending radiuses.
Drawings
FIG. 1 is a schematic view of an initial state of a particle filler assisted push-bending forming method for a large-caliber small-bending-radius thin-wall elbow;
FIG. 2 is a schematic view of an intermediate state of a particle-filled auxiliary push-bending forming method for a large-caliber small-bending-radius thin-wall elbow;
FIG. 3 is a schematic view of a particle-filler assisted large-caliber small-bending-radius thin-wall elbow push-bending forming method in a previous state.
In the figure, 1 — pressure maintaining punch; 2, pushing the head; 3, tube blank; 4-a particulate filler; 5, pushing and bending the die; 6-core print; 7-polyurethane cylinder; 8, a core rod; 9-nylon cylindrical rod; and 10, beveling.
Fig. 4 is a diagram of a large-caliber small-bending-radius thin-wall elbow pipe obtained by a particle filler assisted large-caliber small-bending-radius thin-wall elbow pipe push-bending forming method according to an embodiment of the invention.
Detailed Description
The technical solution of the embodiment of the present invention will be clearly and completely described below with reference to the schematic diagram of the push-bending forming method of the large-caliber small-bending-radius thin-walled elbow pipe in the accompanying drawings, so that the above objects, features and advantages of the present invention can be more clearly understood. The thin-walled stainless steel tube blanks of the embodiments of the drawings are only some embodiments of the invention, and not all embodiments.
As shown in fig. 1-3, the particle filler assisted large-caliber small-bending-radius thin-wall elbow push-bending forming method of the invention realizes bending by using a push head to push a pipe to flow along a die for deformation, realizes internal pressure support by using particle filler compression, realizes internal pressure control by using pressure maintaining punch feeding at two sides, and adjusts the stress state of the pipe during bending by controlling the axial force of the push head to push the pipe and the pressure of the particle filler in real time so as to control the deformation behavior. The method is realized by the following steps:
step 1: blanking the tube blank 3 and performing groove cutting treatment on the inner side of the end part, wherein the blanking length L is more than pi R/2+ L0(ii) a In the formula, R is the radius (mm) of an arc line of a central axis of the push-bending die, and L0 is the sum (mm) of the lengths of straight line segments at two ends of the formed bent pipe. Cutting a 40-degree groove 10 at the head of the bent inner side of the tube blank 3, polishing two ends of the tube blank 3 to eliminate burrs, and properly reducing inner side materials due to the design of the groove 10 because the bent outer side of the tube is stretched in tension and the inner side of the tube is shortened in compression, thereby reducing the risk of inner side wrinkling caused by excessive materials; in the embodiment, the length of the tube blank 3 is 580mm, the outer diameter of the tube blank 3 is 144mm, and the wall thickness of the tube blank 3 is 2 mm;
step 2: the head of the tube blank 3 is filled with a section of nylon cylindrical rod 9 with Shore hardness D90, the diameter of the nylon cylindrical rod 9 is slightly smaller than the inner diameter 2mm of the tube blank 3, and the length of the section of nylon cylindrical rod 9 is 20mm, so that the nylon cylindrical rod 9 and the tube blank 3 form clearance fit;
and step 3: putting the tube blank 3 into a push-bending die 5 from one end of the push-bending die 5, wherein the inner diameter of the push-bending die 5 is the same as the outer diameter of the tube blank 3, and the push-bending die 5 is in sliding fit with the tube blank 3 (see figure 1);
and 4, step 4: a core rod 8 with a core print 6 at one end is placed in a polyurethane cylinder 7, the hardness of the polyurethane cylinder 7 is Shore A85, the outer diameter of the polyurethane cylinder 7 is 2mm smaller than the inner diameter of the push-bending die 5, so that the polyurethane cylinder 7 and the push-bending die 5 form clearance fit, and the inner diameter of the polyurethane cylinder 7 is the same as the inner diameter of the tube blank 3. Putting a polyurethane cylinder 7 and a core rod 8 into a push-bending die 5 together from the other end of the push-bending die 5, wherein the polyurethane cylinder 7 and the core head 6 are initially placed at the bending section of the push-bending die 5, one end surface of the polyurethane cylinder 7 corresponds to and is in top contact with the end surface of the head of the tube blank 3, one end surface of the core head 6 corresponds to and is in top contact with a nylon cylindrical rod 9 at the head of the tube blank 3, the other end of the polyurethane cylinder 7 is positioned in a straight line section at the head of the push-bending die 5, and the other end of the core rod 8 extends out of the push-bending die 5 (see fig.;
and 5: and filling a plurality of particle fillers 4 in the tube blank 3, wherein the particle fillers are made of steel and have the diameter of 1.5mm, and the filling length of the particle fillers 4 is equal to the length of the bent section of the bent tube finally formed by the tube blank 3. Another section of nylon cylindrical rod 9 with Shore hardness D90 is filled at the tail part of the tube blank 3, the diameter of the nylon cylindrical rod 9 is slightly smaller than the inner diameter of the tube blank 3 by 2mm, and the length of the section of nylon cylindrical rod 9 is 20mm, so that the nylon cylindrical rod 9 and the tube blank 3 form clearance fit;
step 6: the pressure maintaining punch 1 is arranged in the tubular push head 2, the push head 2 and the pressure maintaining punch 1 are placed into one end of the push bending die 5, one end face of the push head 2 corresponds to and pushes against the end face of the tail of the tube blank 3, and one end face of the pressure maintaining punch 1 corresponds to and pushes against the nylon cylindrical rod 9 of the tail of the tube blank 3. The pushing head 2 and the pressure maintaining punch 1 push the tube blank 3 forward to move together, the core rod 8 moves backward passively, a certain reverse acting force is applied when the core head 6 of the core rod 8 retreats, and after the polyurethane cylinder 7 reaches the straight-line section of the head of the bending die 5, the pressure is increased by the core rod 8 and balanced with the stress of the pressure maintaining punch 1 to be stationary (see fig. 2);
and 7: after the tube blank 3 enters the bending section, the core rod 8 is reversely pressurized, and the particle filler 4 is compressed under the action of the core rod 8 and the pressure maintaining punch 1 to provide supporting force. And (3) maintaining the pressure of the pressure maintaining punch 1 and the core rod 8, wherein the feeding force of the pressure maintaining punch 1 and the core rod 8 is adjusted to control the internal pressure during pressure maintaining, the particle filler 4 is generally fixed in the pressure maintaining stage, and the tube blank 3 flows forwards under the support of the particle filler 4. The pushing head 2 continues to push the tube blank 3 to move until the tube blank 3 forms a bent tube (see fig. 3).
The core print 6 is a cylindrical chain-type core rod (see the chinese patent publication No. CN109201807A), the core print has the functions of applying passive stress to the front end nylon rod 9 from the initial stage (fig. 1) to the pressure maintaining stage (fig. 2) to ensure that the particle filler 4 moves to the die bending section (fig. 2), and the functions from the pressure maintaining stage (fig. 2) to the final stage (fig. 3) are actively applying counter force and the pressure maintaining punch 1 to ensure that the particle filler 4 generates proper internal pressure to achieve the function of adjusting the internal pressure.
As shown in fig. 4, the large-caliber small-bending-radius thin-wall elbow pipe fitting obtained by the particle filler assisted large-caliber small-bending-radius thin-wall elbow push-bending forming method of the embodiment of the invention has the elbow outer diameter phi of 144mm, the wall thickness of 2mm and the bending radius R280 mm.
The embodiment result shows that the method can push and bend the large-caliber small-bending-radius thin-wall pipe elbow with the straight line segment by controlling the internal pressure of the particle filler, and is suitable for forming the large-caliber small-bending-radius thin-wall bent pipe. The ultra-thin-wall pipe bending forming piece prepared by the equipment and the method well overcomes the defects of the ultra-thin-wall pipe bending forming such as outer side wall stretch cracking, inner side wall wrinkling, oval distortion of cross section, uneven wall thickness and the like.
Claims (8)
1. A particle filler assisted large-caliber small-bending-radius thin-wall bent pipe bending and forming method is characterized in that the method realizes bending by using a pushing head to push a pipe to flow along a die for deformation, internal pressure support is realized by using particle filler compression, internal pressure control is realized by using pressure maintaining punch feeding at two sides, and the stress state of the pipe during bending is adjusted by controlling the axial force of the pushing head to push the pipe and the pressure of the particle filler in real time, so that the deformation behavior is controlled;
the method is carried out according to the following steps:
step 1: blanking the tube blank and beveling the inner side of the end part of the tube blank, and the blanking length of the tube blank
(ii) a In the formula, R is the radius of an arc line of a central axis of the push-bending die and is in mm; l is0The length sum of straight line segments at two ends of the formed bent pipe is unit mm;
step 2: filling a section of nylon cylindrical rod at the head of the tube blank;
and step 3: putting one end of the tube blank self-bending die into the bending die;
and 4, step 4: putting a core rod with a core print at one end into a polyurethane cylinder, putting the polyurethane cylinder and the core rod into a bending mould together from the other end of the bending mould, and initially placing the polyurethane cylinder and the core print at the bending section of the bending mould;
and 5: filling particle fillers in the tube blank, wherein the filling length of the particle fillers is equal to the length of the bending section of the finally formed bent tube of the tube blank, and filling another section of nylon cylindrical rod at the tail of the tube blank;
step 6: the pushing head and the pressure maintaining punch head push the pipe blank forward to move together, the core rod moves backward passively, a reverse acting force is applied when the core head of the core rod retreats, and after the polyurethane cylinder is completely pushed to a straight line section of the head of the bending die, the pressure is increased through the core rod and the pressure maintaining punch head is stressed to balance and stand still;
and 7: after the tube blank enters a bending section, the core rod is reversely pressurized, and the particle filler is compressed under the action of the core rod and the pressure maintaining punch head to provide supporting force; maintaining the pressure of the pressure maintaining punch and the core rod, wherein the feeding force of the pressure maintaining punch and the core rod is adjusted to control the internal pressure during pressure maintaining, the particle filler is generally fixed in the pressure maintaining stage, and the tube blank flows forwards under the support of the particle filler; the pushing head continues to push the tube blank to move until the tube blank forms a bent tube.
2. The push-bending forming method of the large-caliber small-bending-radius thin-wall elbow pipe assisted by the particle filler according to claim 1, characterized in that in the step 1, a groove of 15-75 degrees is cut on the inner side of one end of the pipe blank.
3. The push-bending forming method of the large-caliber small-bending-radius thin-wall elbow pipe assisted by the particle filler according to claim 1, characterized in that in the step 2 and the step 5, the hardness of the nylon cylindrical rod is Shore D80-90, and the diameter of the nylon cylindrical rod is smaller than the inner diameter of the pipe blank by 1-3 mm, so that the nylon cylindrical rod and the pipe blank form clearance fit.
4. The method for push-bending forming of the large-caliber small-bending-radius thin-wall elbow pipe assisted by the granular fillers according to claim 1, wherein in the step 3, the inner diameter of the push-bending die is the same as the outer diameter of the pipe blank, and the push-bending die is in sliding fit with the pipe blank.
5. The method for push-bending forming of the large-caliber small-bending-radius thin-wall elbow pipe assisted by the particle filler according to claim 1, wherein in the step 4, the hardness of the polyurethane cylinder is Shore A40-100, the outer diameter of the polyurethane cylinder is 1-3 mm smaller than the inner diameter of the push-bending die, so that the polyurethane cylinder and the push-bending die form clearance fit, and the inner diameter of the polyurethane cylinder is the same as the inner diameter of the pipe blank.
6. The push-bending forming method of the large-caliber small-bending-radius thin-wall bent pipe assisted by the particle filler according to claim 1, wherein in the step 4, one end face of the polyurethane cylinder corresponds to and is in contact with the end face of the head of the pipe blank, and the other end of the polyurethane cylinder is positioned in a straight line section of the head of the push-bending die; one end face of the core head corresponds to and is in top contact with the nylon cylindrical rod at the head of the tube blank, and the other end of the core rod extends out of the push bending die.
7. The push-bending forming method of the large-caliber small-bending-radius thin-wall bent pipe assisted by the particle filler according to claim 1, wherein in the step 5, the particle filler is made of metal, ceramic or plastic, and the diameter of the particle filler is 0.5 mm-10 mm.
8. The method for push-bending forming of a large-caliber small-bending-radius thin-wall bent pipe assisted by granular fillers according to claim 1, wherein in the step 6, the pressure maintaining punch is arranged in a tubular push head, the push head and the pressure maintaining punch are placed into one end of the push-bending die, one end surface of the push head corresponds to and is in push contact with the end surface of the tail of the pipe blank, and one end surface of the pressure maintaining punch corresponds to and is in push contact with the nylon cylindrical rod at the tail of the pipe blank.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910716300.2A CN110576089B (en) | 2019-08-05 | 2019-08-05 | Particle filler assisted push-bending forming method for large-caliber small-bending-radius thin-wall bent pipe |
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| CN201910716300.2A CN110576089B (en) | 2019-08-05 | 2019-08-05 | Particle filler assisted push-bending forming method for large-caliber small-bending-radius thin-wall bent pipe |
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| CN110576089B true CN110576089B (en) | 2020-08-21 |
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| CN112974588B (en) * | 2021-02-03 | 2022-11-25 | 日照职业技术学院 | Low-pressure stretch bending method for hollow part with extremely small bending radius |
| CN113942241B (en) * | 2021-09-26 | 2023-11-03 | 广东伟达智能装备股份有限公司 | Jacketing machine |
| CN114346026B (en) * | 2022-01-06 | 2023-05-09 | 南昌航空大学 | Pushing bending device |
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| JPS5115512B2 (en) * | 1971-11-13 | 1976-05-17 | ||
| AT402479B (en) * | 1994-04-12 | 1997-05-26 | Erne Fittings Gmbh & Co | METHOD AND DEVICE FOR BENDING HOLLOW PROFILE WORKPIECES |
| JPH0819821A (en) * | 1994-07-04 | 1996-01-23 | Sanetsu:Kk | Method for bending plastic steel pipe |
| JPH08300052A (en) * | 1995-04-28 | 1996-11-19 | Showa Alum Corp | Bending method of hollow material, hollow material and both end cap device of hollow material |
| CN102228922B (en) * | 2011-04-20 | 2013-01-16 | 桂林电子科技大学 | Method for bending and forming metal pipe by placing steel balls inside |
| US10010921B2 (en) * | 2016-12-06 | 2018-07-03 | Hamid Reza Abbasi | Methods for bending thin-walled tubes |
| CN106734438B (en) * | 2017-01-13 | 2018-05-29 | 南昌航空大学 | A kind of small curvature bending radius L type thin-wall aluminum alloy bend pipe of band pushes away o ing method |
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