CN111957806A

CN111957806A - Bent pipe forming process for bulging bent pipe

Info

Publication number: CN111957806A
Application number: CN202011151707.4A
Authority: CN
Inventors: 张峰; 刘�文; 郑浩民; 林立; 王春鸽; 陈怡江; 滕叶莹; 王沛超; 张池; 王文兵
Original assignee: Zhejiang University of Science and Technology ZUST
Current assignee: Zhejiang University of Science and Technology ZUST
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2020-11-20
Anticipated expiration: 2040-10-26
Also published as: CN111957806B

Abstract

The invention discloses a bend pipe forming process of an expanded bend pipe, which comprises the following process steps: step one, pipe material loading: placing the pipe to be processed into an expanding die so as to clamp the pipe to be processed; step two, sealing the pipe: two ends of the pipe are blocked by a pair of movable plugs; step three, internal high-pressure bulging: the hydraulic system works, liquid is pressed into the pipe through the plug, and high-pressure bulging is carried out on the pipe corresponding to the bulging die channel; step four, inner low-pressure bending: controlling a hydraulic system to reduce the internal pressure of the pipe below the plastic deformation pressure of the pipe, rotating a first die and a second die, and bending the whole expanded pipe; step five, blanking of the pipe: and removing the liquid in the pipe, moving out the plugs at the two ends of the pipe, and separating the first die and the second die to take out the finished bent pipe. The bent pipe manufactured by the process is not easy to collapse and wrinkle at the bent position, the product quality is high, the manufacturing period of the bent pipe can be shortened, and the yield is higher.

Description

Bent pipe forming process for bulging bent pipe

Technical Field

The invention relates to the technical field of bulging pipe manufacturing, in particular to a bent pipe forming process of a bulging bent pipe.

Background

The bulging bent pipe is a pipe bent by a bending machine after being formed by a bulging process, and is commonly used in a water distribution system. At present, the two processes of bulging and bending are generally carried out separately, the process continuity is poor, particularly the bending process, the existing pipe bending process is easy to collapse and wrinkle when processing pipes with thin wall thickness, the appearance of the pipes is damaged, the adverse effect that the pipes cannot be installed and used can be caused, the rejection rate of pipe bending is high, and the quality of the pipes after bending is poor.

Because the bulging bending process and the bending process are independent in the manufacturing process, a forming device and a bending device (automatic or manual) are respectively needed to respectively realize two actions of bulging and bending of the pipe to be processed, because the relevance between the two actions is not large, the devices for realizing the two actions are mutually independent and cannot share resources, after the bulging process is finished, a transfer of the pipe must be carried out, the transfer of the pipe from the bulging equipment to the bending equipment requires an additional time for taking and placing the pipe, namely, the pipe is taken down from a clamping device of the bulging equipment and then assembled on the clamping device of the bending equipment, and then the bending process is carried out, so that the pipe transfer not only needs a certain time to be finished, and the production efficiency is low, and the pipe has the risk of damage in the transferring process, so that the time is consumed, and the yield of the product is reduced.

Disclosure of Invention

The invention aims to provide a bent pipe forming process of an expanded bent pipe. The bent pipe manufactured by the process is not easy to collapse and wrinkle at the bending position, and the product quality is high; the invention can also shorten the manufacturing period of the bent pipe and has higher yield.

The technical scheme of the invention is as follows: a pipe bending forming process for an expanded bent pipe comprises the following process steps:

step one, pipe material loading: placing a pipe to be processed into an expansion mould so as to clamp the pipe to be processed, wherein the expansion mould comprises a first mould and a second mould which can form a section of expansion mould channel after mould assembly, and the second mould is provided with a pipe bending groove;

step two, sealing the pipe: the two ends of the pipe are blocked by a pair of movable plugs to form the sealing of the two ends of the pipe;

step three, internal high-pressure bulging: the hydraulic system works, liquid is pressed into the pipe through the plug, and high-pressure bulging is carried out on the pipe corresponding to the bulging die channel;

step four, inner low-pressure bending: after the bulging is finished, controlling a hydraulic system to reduce the pressure in the pipe below the plastic deformation pressure of the pipe, rotating a first die and a second die, and enabling a pipe bending groove on the second die to act on the part of the pipe which is not bulged, so that the whole pipe after the bulging is bent;

step five, blanking of the pipe: and after the pipe bending is finished, stopping the work of the hydraulic system, removing the liquid in the pipe, moving out the plugs at the two ends of the pipe, and separating the first die and the second die to take out the finished bent pipe.

Compared with the prior art, the invention has the beneficial effects that: the two steps of bulging and pipe bending are continuously carried out, and the transfer action of the pipe is not required between the two steps, so that the production period of the pipe bending is greatly shortened, and the production efficiency is high; according to the invention, after the pipe is expanded, the liquid in the pipe does not need to be removed, the liquid can be reused to participate in the internal low-pressure bending action of the pipe, so that the supporting force is provided for the inner wall of the pipe, the pipe can be effectively prevented from collapsing and wrinkling in the bending process, the produced bent pipe has higher quality, and the yield is also higher; in addition, because the pipe transfer action is not needed between the bulging step and the pipe bending step, the intermediate step is reduced, which means that the pipe does not need to bear the damage risk possibly generated in the transfer process, and the yield is further improved.

In the pipe bending process for forming the bulging bent pipe, when the pipe is bent in the fourth step, the plugs at the two ends of the pipe move synchronously along with the movement of the positions of the two ends of the pipe, so that the relative positions of the plugs and the ends of the pipe are kept unchanged.

In the above-mentioned pipe bending process for forming the expanded bent pipe, the pipe bending groove is in a semicircular arc shape and is connected to the expanded die path on the second die, and the first die and the second die in the fourth step rotate with the central axis of the circle where the pipe bending groove is located as a rotating shaft.

In the above-mentioned pipe bending process for forming the expanded bend pipe, the closing of the first die and the second die in the first step and the splitting of the second die in the fifth step are both driven by hydraulic cylinders.

In the bend pipe forming process for the bulging bend pipe, the internal pressure of the pipe is gradually increased from 0MPa to 80MPa during internal high-pressure bulging in the third step.

In the pipe bending forming process for the bulging bent pipe, the duration time of the internal high-pressure bulging in the third step is 10 to 20 seconds.

In the bend pipe forming process for the bulging bend pipe, the internal pressure of the pipe is 6-10MPa when the pipe is bent at the middle and low pressure in the fourth step.

In the above elbow pipe forming process for the bulging elbow pipe, the duration of the low-pressure elbow pipe in the middle of the fourth step is 10 to 20 seconds.

Drawings

FIG. 1 is a schematic diagram of an apparatus for carrying out the process of the present invention;

FIG. 2 is an enlarged view of a portion of FIG. 1 at A;

FIG. 3 is a schematic view of the device of FIG. 1 from another perspective;

FIG. 4 is a schematic structural view of a sealing mechanism;

fig. 5 is a sectional view of the internal structure of the sealing mechanism;

FIG. 6 is an enlarged view of a portion of FIG. 5 at B;

FIG. 7 is a schematic structural view of the tube bending mechanism;

FIG. 8 is a schematic view of the structure of the flexure arm;

FIG. 9 is a schematic structural view of a second mold;

fig. 10 is a partial enlarged view of fig. 6 at C.

Reference numerals: 11-a first die, 12-a second die, 13-an expanding die way, 14-a third die, 15-a fourth die, 16-a straight tube die way, 17-a first hydraulic cylinder, 18-a second hydraulic cylinder, 21-a bending arm, 22-a rotating shaft, 23-a gear, 24-a rack, 25-a third hydraulic cylinder, 30-a choke plug, 31-a push rod, 32-a cone block, 33-a fourth hydraulic cylinder, 34-a rubber ring, 35-a four-jaw block, 36-a baffle, 37-a push rod, 38-a fifth hydraulic cylinder, 41-a hydraulic pipe joint, 42-a hydraulic pipe, 43-a self-priming pump, 44-a water tank, 51-a frame, 121-a bending pipe groove, 211-a sliding groove, 311-a clamping groove, 342-a convex ring and 343-a ring groove, 344-connecting edge, 345-upper cavity, 346-lower cavity, 347-side cavity.

Detailed Description

The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.

Example (b): an integral forming pipe bending device for manufacturing an expanded bent pipe by adopting the process has the structure shown in figures 1 to 3, and comprises a die set, a pipe bending mechanism, a hydraulic system and sealing mechanisms arranged at two ends of the die set; the die set is used for clamping and bulging the pipe to be processed, and the hydraulic system provides bulging internal pressure for the pipe to be processed; the die set comprises a first die 11 and a second die 12 which are oppositely arranged; the pipe bending mechanism structure is shown in fig. 7 and 8, and comprises a rotatable bending arm 21, the bending arm 21 is integrally in an L shape, the transverse and vertical intersection point of the L shape is the rotation point of the bending arm, and the bending arm 21 drives the first die 11 and the second die 12 to synchronously rotate when rotating; the second die 12 is provided with a pipe bending groove 121, and the structure is as shown in fig. 9, and the pipe bending groove 121 acts on the pipe to bend the pipe along with the rotation of the second die 12; the sealing mechanism comprises a plug 30 for plugging the end part of the pipe, and when the pipe is bent, the plug 30 moves synchronously along with the movement of the end part of the pipe.

Further, a section of bulging die channel 13 is formed after the first die 11 and the second die 12 are closed, that is, the required molding shape of the product is obtained, a third die 14 and a fourth die 15 which are oppositely arranged are arranged on the same side of the first die 11 and the second die 12, the third die 14 and the fourth die 15 are respectively adjacent to and closely attached to the first die 11 and the second die 12, and a section of straight tube die channel 16 connected with the bulging die channel 13 is formed after the third die 14 and the fourth die 15 are closed, so that the overall continuity of the die channels is ensured.

Further, the bending arm 21 and the second die 12 have the same rotation center, the pipe bending groove 121 on the second die 12 is in a semi-circular arc shape, and one side of the fourth die 15 is embedded into the pipe bending groove 121, so that the main die path can always keep good continuity when the bending action is performed.

Further, the bending arm 21 is provided with a sliding groove 211, and the bottom of the first mold 11 is embedded in the sliding groove 211 and can be translated along the sliding groove 211 to realize mold closing and mold splitting with the second mold 12.

Furthermore, the first die 11 is connected with a first hydraulic cylinder 17, the third die 14 is connected with a second hydraulic cylinder 18, the first hydraulic cylinder 17 is arranged on the bending arm 21, and the first hydraulic cylinder 17 and the second hydraulic cylinder 18 respectively drive the first die 11 and the third die 14 to realize die closing and die separating actions.

Further, the pipe bending mechanism further comprises a rotating shaft 22 for driving the bending arm 21 to rotate, the rotating shaft 22 and the bending arm 21 keep relatively static in the movement process, preferably, a shaft hole matched with the rotating shaft 22 can be formed in the bending arm 21, the rotating shaft 22 and the rotating shaft 22 keep relatively static when rotation is achieved, a gear 23 is arranged on the rotating shaft 22, the gear 23 is connected with a rack 24, the rack 24 is connected with a third hydraulic cylinder 25, the rack 24 is driven by the third hydraulic cylinder 25 to move, and the rack 24 is meshed with the gear 23, so that the bending arm 21 is driven to rotate.

The top of the rotating shaft 22 is arranged to be higher than the top of the bending arm 21, the second die 12 can be provided with the same shaft hole which is sleeved on the rotating shaft 22, and the top of the second die 12 is provided with a clamping nut, so that the second die 12 can keep coaxial and synchronous rotation with the bending arm 21.

Further, the sealing mechanism comprises a plug 30 and a support for supporting the plug 30, the structure is shown in fig. 4 to 6, the plug 30 comprises a push rod 31, one end of the push rod 31 is provided with a conical block 32, the conical block 32 gradually decreases from the outer cross-sectional area to the inner cross-sectional area, the other end of the conical block 32 is connected with a fourth hydraulic cylinder 33, a hollow section communicated with the end where the conical block 32 is located is arranged inside the push rod 31, the outer side of the conical block 32 is sleeved with a rubber ring 34, a four-claw block 35 is further arranged between the rubber ring 34 and the conical block 32, the tail end side of the rubber ring 34 is provided with a baffle plate 36, one side of the baffle plate 36 is provided with a push rod 37, and the push; when sealing is carried out, the fourth hydraulic cylinder 33 drives the push rod 31 to push the rubber ring 34 into the pipe, at the moment, the baffle plate 36 covers the end opening of the pipe, the fifth hydraulic cylinder 38 drives the ejector rod 37 to prop against the baffle plate 36, the fourth hydraulic cylinder 33 drives the push rod 31 to contract, the conical block at the top of the push rod 31 acts on the four-jaw block 35, the four-jaw block 35 acts on the rubber ring 34, the rubber ring 34 expands radially, and the expanded rubber ring 34 forms bionic friction sealing at two ends of the pipe.

Further, the outer circumferential surface of the rubber ring 34 is configured as shown in fig. 10, the outer circumferential surface of the rubber ring 34 is provided with a plurality of convex rings 342, the convex rings 342 are arranged at intervals along the radial direction, a ring groove 343 is formed between two adjacent convex rings 342, and the convex rings 342 are arranged in an inclined manner towards the direction of the baffle plate 36. The convex rings 342 are provided with an upper layer cavity 345 and a lower layer cavity 346, a connecting edge 344 is obliquely arranged between two adjacent convex rings 342, side cavities 347 are formed between the two adjacent convex rings 342, the connecting edge 344 and the rubber ring 34 in a matching manner, and the cross sections of the upper layer cavity 345, the lower layer cavity 346 and the side cavities 347 are all wedge-shaped, so that the convex rings 342 are easy to deform.

Because the inside undulant pressure that receives of tubular product, undulant pressure change is great moreover, if directly sealed through rubber circle 34, undulant power can transmit to rubber circle 34, and rubber circle 34 can receive undulant axial force, can promote rubber circle 34 and remove, influences sealed effect, can cause rubber circle 34 to take place to warp moreover, influences sealed effect.

According to the invention, the ejector rod 37 and the fifth hydraulic cylinder 38 are arranged, so that axial thrust can be generated on the rubber ring 34, the rubber ring 34 is kept balanced with axial power generated by fluctuation in a pipe, the rubber ring 34 is prevented from moving, the easily-deformable convex ring 342 is arranged on the periphery of the rubber ring 34, so that the convex ring 342 can be tightly attached to the inner wall of the pipe, the convex ring 342 is obliquely arranged and can be tightly abutted against the inner wall of the pipe conveniently, after the rubber ring 34 is subjected to axial action, when the rubber ring 34 deforms, the convex ring 342 can still be tightly attached to the inner wall of the pipe, the contact area between the rubber ring 34 and the inner wall of the pipe is increased, good sealing performance is ensured, and the adjacent two convex rings 342 are arranged at intervals, so that the annular groove 343 is formed between the two adjacent convex rings 342, the annular groove 343 can play a storage role, when water leaks from the pipe, the leaked water can be stored through the annular, the water is prevented from leaking to the outside to ensure the sealing effect of the rubber ring 34. The upper layer cavity 345, the lower layer cavity 346 and the side cavity 347 are distributed in a honeycomb shape, so that after the convex ring 342 deforms, the convex ring 342 can generate a large reaction force, the convex ring 342 can be always in tight contact with the inner wall of the pipe, and after the rubber ring 34 receives the axial action force fluctuating in the pipe, the convex ring 342 can still be in tight contact with the inner wall of the pipe, so that the sealing requirement can be met.

Further, the rubber ring 34 and the push rod 31 outer side corresponding to the baffle 36 are provided with a clamping groove 311, the rubber ring 34 and the baffle 36 are all embedded into the clamping groove 311, when the rubber ring 34 is pushed into the pipe, the end opening of the pipe covered by the baffle 36 is used as a position determination point, and the tail end of the clamping groove 311 is the limit movement position of the baffle 36.

Further, the outside of push rod 31 is equipped with and inserts and communicate the hydraulic pressure coupling 41 of the inside hollow section of push rod 31 from the push rod 31 lateral wall, and hydraulic pressure coupling 41 and push rod 31 lateral wall threaded connection, hydraulic pressure coupling 41 is connected with high pressure self priming pump 43 through hydraulic pressure pipe 42, high pressure self priming pump 43 is connected with water tank 44.

Further, the hydraulic pipe 42 is a flexible ultrahigh pressure hydraulic pipe 42, so that the hydraulic pipe 42 can deform and move within a small range in the pipe bending process, particularly, the hydraulic pipe 42 on the side where the third die 14 and the fourth die 15 are located is slightly reduced in axial length when the pipe is bent, and the fourth hydraulic cylinder 33 and the fifth hydraulic cylinder 38 on the side need to simultaneously drive the push rod 31 and the ejector rod 37 to move to compensate the reduction in axial length of the pipe; here, it should be noted that although the sealing mechanism structures of the two ends of the die set are the same, since the sealing mechanisms on the sides of the first die 11 and the second die 12 are also mounted on the bending arm 21, the sealing mechanisms can synchronously rotate along with the first die 11 and the second die 12, and the fourth hydraulic cylinder 33 and the fifth hydraulic cylinder 38 on the sides are not required to be operated when the pipe is bent.

Further, the integrated pipe bending device further comprises a frame 51, wherein the mold set, the pipe bending mechanism, the hydraulic system and the sealing mechanism are all arranged on the frame 51, and the hydraulic system is located at the bottom end of the frame 51.

The process of the invention combines the above-mentioned apparatus to produce a bulging bend which is used as an outer pipe of a silencer, the finished outer pipe is produced with two bulging corrugations, the pipe bending angle is 90 °:

the material of the pipe is 304 stainless steel, the length of the pipe to be processed is 272mm, and the wall thickness is 0.8 mm;

step one, pipe material loading: placing a pipe to be processed into a second die 12 and a fourth die 15, driving a first die 11 to realize die assembly with the second die 12 by a first hydraulic cylinder 17, and driving a third die 14 to realize die assembly with the fourth die 15 by a second hydraulic cylinder 18, so that the pipe to be processed is clamped;

step two, sealing the pipe: a fourth hydraulic cylinder 33 of the sealing mechanism at the two ends of the die set drives a push rod 31 to push the rubber ring 34 into the pipe, a fifth hydraulic cylinder 38 drives a push rod 37 to prop against a baffle 36, the fourth hydraulic cylinder 33 drives the push rod 31 to contract, so that a conical block at the top of the push rod 31 acts on a four-jaw block 35, and the four-jaw block 35 expands the rubber ring 34 to form sealing at the two ends of the pipe;

step three, internal high-pressure bulging: the hydraulic system works, liquid is pressed into the pipe through the plug 30, the pipe corresponding to the bulging die channel 13 is subjected to high-pressure bulging, the internal pressure of the pipe is gradually increased from 0MPa to 80MPa, and the duration time is 15 s;

step four, inner low-pressure bending: after the bulging is finished, controlling a hydraulic system to reduce the internal pressure to be below the plastic deformation pressure of the pipe, extending a hydraulic rod of a third hydraulic cylinder 25 to drive a rack 24 to move, meshing the rack 24 with a gear 23 to drive a bending arm 21 to rotate, synchronously rotating a first die 11 and a second die 12, acting a pipe bending groove 121 on the second die 12 on the part of the pipe which is not bulged, and bending the whole bulged pipe to obtain a finished bent pipe;

and step four, when the pipe is bent at the middle and low pressure, the internal pressure of the pipe is 8Mpa, and the duration time is 15 s.

After the bulging action is finished, the liquid in the pipe does not need to be removed, the liquid directly participates in the bending action of the pipe to provide supporting force for the inner wall of the pipe, the pipe can be effectively prevented from collapsing and wrinkling in the bending process, the produced bent pipe is higher in quality, namely the liquid in the hydraulic system not only participates in the bulging action, but also participates in the bending action, and resource sharing is realized;

step five, blanking of the pipe: after the pipe bending is finished, the hydraulic system stops working, liquid in the pipe is removed, the fourth hydraulic cylinder 33 drives the push rod 31 to extend, the rubber ring 34 recovers, the fifth hydraulic cylinder 38 drives the ejector rod 37 to be away from the baffle 36, the fourth hydraulic cylinder 33 drives the push rod 31 to contract again, the push rod 31 and the rubber ring 34 are driven to be separated from the two ends of the finished bent pipe, the hydraulic rods of the first hydraulic cylinder 17 and the second hydraulic cylinder 18 contract to drive the first die 11 and the third die 14 to reset, the finished bent pipe is taken out, and the processing is finished.

Compared with the prior art in which the bulging and the bending are carried out separately, the production efficiency is improved by 35 percent, the yield is 1.2 times of the prior art, the ellipticity of the finished product is less than 1 percent, the waviness of the inner arc side is less than 1.32mm, and the quality is higher.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned examples, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.

Claims

1. A pipe bending forming process for an expanded bent pipe is characterized by comprising the following process steps:

2. The pipe bending process for forming an expanded bend pipe according to claim 1, wherein: and step four, when the pipe is bent, the plugs at the two ends of the pipe move synchronously along with the movement of the positions of the two ends of the pipe, so that the relative positions of the plugs and the end parts of the pipe are kept unchanged.

3. The pipe bending process for forming an expanded bend pipe according to claim 1, wherein: the pipe bending groove is in a semicircular arc shape and is connected with the bulging die way on the second die, and the first die and the second die in the fourth step rotate by taking the central axis of the circle where the pipe bending groove is located as a rotating shaft.

4. The pipe bending process for forming an expanded bend pipe according to claim 1, wherein: the first die and the second die are driven by a hydraulic cylinder in the die closing process in the step one and the die parting process in the step five.

5. The pipe bending process for forming an expanded bend pipe according to claim 1, wherein: and in the third step, the internal pressure of the pipe is gradually increased from 0MPa to 80MPa during internal high-pressure bulging.

6. The pipe bending process according to claim 1 or 5, wherein: the duration of the high-pressure bulging in the third step is 10-20 s.

7. The pipe bending process for forming an expanded bend pipe according to claim 1, wherein: and step four, the internal pressure of the pipe is 6-10MPa when the pipe is bent at the middle and low pressure.

8. The pipe bending process according to claim 1 or 7, wherein: and step four, the duration of the low-pressure elbow pipe in the middle and the low pressure elbow pipe is 10-20 s.