CN104607520B - Spinning mechanism and method for forming corrugated pipe - Google Patents

Abstract

The invention discloses a spinning mechanism and method for forming a corrugated pipe. A core shaft is sleeved with a core die which is sleeved with a blank, and the blank is fixed through four clamping blocks located at one end of the core shaft (1). The core die comprises a straight-wall core die body and a corrugated core die body, and in the process of forming the corrugated pipe, different core die bodies are selected according to different processes. Through three times of spinning, the size precision of the finally formed part is guaranteed, integrated plastic forming of the corrugated pipe in the whole process is achieved, in this way, plastic work hardening occurs, the obtained corrugated pipe is free of splicing, and the mechanical property of the workpiece is improved.

Description

Spinning mechanism and spinning method for forming bellows

technical field

The invention belongs to the field of spinning processing, in particular to a spinning mechanism and spinning method for forming bellows.

Background technique

Aluminum alloy corrugated pipe fittings are widely used in military defense, aerospace, oil exploration, oil and gas transportation and other industrial fields due to their light weight and corrosion resistance. Bellows is a tubular part composed of straight wall sections and corrugated sections alternately, where each corrugated section is composed of three arcs, namely the top arc and two root arcs. The traditional corrugated pipe forming method is to first press the convex groove on the slab, then longitudinally round and weld it to form a short corrugated pipe, and finally process the multi-section short corrugated pipe through axial tailor welding to form the final finished corrugated pipe. The above-mentioned traditional forming methods use many kinds of processes, including four processes of grooving, rounding, roll welding, and tailor welding, which lead to various defects in the forming process, and it is difficult to guarantee the final forming quality. In addition, the bellows made by the above-mentioned traditional forming method contains a large number of welds, so it is prone to defects such as welding cracks, incomplete penetration, slag inclusions, pores, and weld appearance defects, which seriously affect the corrugation. Tube formability and service life.

New aerospace products require reliable and stable performance, among which the processing and manufacturing of bellows requires minimizing the types of processes used, canceling longitudinal and transverse welds, and realizing integral forming. Spinning forming, as an advanced plastic forming technology, is an important branch of modern net-minimum-less-cut integral forming technology, and it has become a process that should be given priority in the forming of thin-walled hollow rotating parts. During the spinning process, one end of the blank is fixed by the clamping device and realizes its own rotation along the axis, and the blank is fed along the axial direction of the blank with a certain trajectory through the rotary wheel with or without the support of the mandrel. Realize the change of workpiece shape and wall thickness. Compared with other forming processes, spinning has the advantages of high product precision, good performance, high material utilization, low cost, small tonnage of required equipment and high process flexibility.

In the invention with the publication number CN103332354A, aiming at the shortcomings of low efficiency and poor stability of manual crimping of corrugated pipes, a device with compact structure and capable of crimping corrugated pipes under the state of numerical control is proposed, and a A method of "assembling pipe clamps-bellows blanking-continuing blanking"; this method still cannot solve the defects of the traditional method of forming bellows fittings with various types of processes and many finished welds. Therefore, it is urgent to use the spinning method to form bellows with no weld seam, simple process and integral formation, so as to meet the requirements of reliable and stable performance of new aerospace products.

Contents of the invention

In order to overcome the disadvantages of complicated processes and many weld seams in the prior art, the present invention proposes a spinning mechanism and spinning method for forming bellows.

The invention comprises a mandrel, a mandrel, a clamping block, a corrugated mandrel, a mandrel end cover, a corrugated forming rotary wheel and a shape correcting rotary wheel. Wherein: the mandrel is set on the mandrel, the blank is set on the mandrel, and fixed by four clamping blocks located at one end of the mandrel 1 . The mandrels are divided into straight wall mandrels and corrugated mandrels. In forming corrugated pipes, different mandrels are selected according to different processes.

The mandrel is a three-stage stepped shaft, which respectively forms a clamp block installation boss section, a billet fixing section and a mandrel matching section. Wherein, the blank fixing section is located in the middle of the mandrel. The outer diameter of the blank fixing section is slightly smaller than the clamp block installation boss, and the end surface of the step between the blank fixation section and the clamp block installation boss section forms a blank positioning surface. Two threaded holes for connecting the core mold are symmetrically opened on the end face of the step between the blank fixing section and the mandrel matching section.

There are four clamping blocks, and the lower surface of each clamping block is an arc surface. The curvature of the arc surface is respectively the same as the curvature of the matching clip block installation boss section and the curvature of the blank.

The corrugated mandrel is a split mandrel, and the shape and size of the outer surface of the corrugated mandrel are the same as the shape and size of the inner surface of the corrugated pipe. Each corrugated segment in the corrugated mandrel is composed of three arcs, which are respectively a top arc and two root arcs, and the radius of each arc satisfies formula (1):

rm ₁ =r ₁ =R ₁ +t (1)

rm ₂ =r ₂ =R ₂ +t

Among them, rm ₁ is the radius of the arc at the root of the corrugated section of the corrugated mandrel, and rm ₂ is the radius of the arc at the top of the corrugated section of the corrugated mandrel. r ₁ is the fillet radius at the root of the corrugated section on the inner surface of the bellows, and r ₂ is the fillet radius at the top of the corrugated section on the inner surface of the bellows. R ₁ is the fillet radius at the root of the corrugated section on the outer surface of the bellows, and R ₂ is the fillet radius at the top of the corrugated section on the outer surface of the bellows. t is the wall thickness of the bellows.

The roller forming surface of the roller for forming corrugations is divided into three arc segments, which are respectively the middle arc segment rs ₁ and the two end arc segments rs ₂ , and the radius of each arc segment satisfies formula (2):

rs ₁ < R ₁

rs ₂ >R ₂ (2)

Among them, rs ₁ is the fillet radius of the middle arc section of the roller forming surface, and rs ₂ is the fillet radius of the arc sections at both ends of the roller forming surface.

The arc section rs ₁ in the middle of the rotary wheel is 3-4 mm smaller than the root fillet radius R ₁ of the outer surface of the bellows, and the arc section rs ₂ at both ends of the rotary wheel is 3-4 mm larger than the top fillet radius R ₂ of the outer surface of the bellows .

The roller forming surface of the roller for correcting the shape is groove _- shaped. The arc radius rb ₂ in the middle of the mold area and the arc radius rb ₃ at the end of the forming surface of the rotary wheel are used to accurately form the outer surface of the corrugated pipe. match, as shown in formula (3):

rb ₁ =R ₁

rb ₂ =R ₂ (3)

rb ₃ ≈ rb ₁

Among them, rb ₁ is the arc radius of the root of the groove area of the roller forming surface, rb ₂ is the radius of the arc in the middle of the groove area of the roller forming surface, and rb ₃ is the radius of the arc at the end of the roller forming surface.

A method for forming a bellows by using the spinning mechanism, the specific process is:

Step 1, thinning and spinning the cylindrical workpiece. Thinning and spinning of cylindrical workpieces is carried out by conventional spinning thinning method. Specifically, the original blank is fixed by clamping blocks to realize the synchronous rotation of the blank and the mandrel. The straight wall mandrel is adopted and installed on the mandrel through the mandrel end cover to realize the synchronous rotation of the straight wall mandrel and the mandrel. Three powerful spinning wheels are used and distributed evenly at an angle of 120° along the circumference. The rotary wheel track adopts axial linear feed. The rotating speed of the mandrel is 90r/min, the feeding speed of the rotary wheel is 1mm/r, and the axial feeding length is slightly larger than the length of the workpiece. A thinned cylindrical workpiece is obtained.

Step 2, corrugated forming and spinning. The process of corrugation forming and spinning adopts coreless die-reducing spinning. Remove the straight-wall mandrel in the spinning mechanism, and replace the three powerful spinning wheels with three forming corrugated wheels. The track of the rotary wheel is similar to the shape of the bellows; the corrugated section of the track is composed of three arcs, namely the top arc rp ₁ and the two root arcs rp ₂ , and the arc radius satisfies formula (4):

rp ₁ =R ₁ -rs ₁

(4)

rp ₂ =R ₂ +rs ₁

In the formula, rp ₁ is the arc radius of the root of the corrugated section in the wheel track, and rp ₂ is the arc radius of the top of the corrugated section in the wheel track.

The distance between the track of the rotary wheel and the contour of the bellows is rs ₁ .

Spinning the cylindrical workpiece formed in step 1 through corrugation forming, and forming a corrugated shape on the surface of the cylindrical workpiece by spinning.

Step 3, the corrugation shaping and spinning process. Put the split corrugated mandrel into the corrugated cylindrical workpiece.

The corrugated mandrel and the workpiece are set together on the mandrel installation section of the mandrel 1, and the corrugated mandrel and the mandrel are fixed through the mandrel end cover, and the cylindrical workpiece is fixed by the clamp block, so as to realize Synchronous rotation of workpiece, corrugated mandrel and mandrel. Replace the three forming corrugation rollers with three correcting rollers. Set the rotational speed of the mandrel to 60r/min. Each section of corrugation and the transition between the section of corrugation and the straight section are fed radially and linearly by three shaping rollers section by section, so as to obtain the precisely formed corrugated section of the cylindrical workpiece.

So far, the spinning forming of the bellows has been completed.

The spinning mechanism proposed by the present invention is based on the multi-roller powerful flow spinning machine widely used at present. The corrugated pipe is obtained through three spinning processes. Mechanism and effect of the present invention are as follows:

Thinning process: The blank is thinned into a thin-walled cylindrical part by strong spinning, so that the wall thickness is thinned and the axial direction is lengthened, so that the wall thickness of the blank tends to the wall thickness of the final part, and the subsequent corrugation forming process is reduced. deformation resistance in .

Forming process: The corrugated section is formed on the cylinder wall by coreless spinning, so that the diameter of the straight wall section is shortened, and the circumferential compression is axially stretched, thereby forming a corrugated area. The amount of deformation in the corrugation forming process is relatively large, and this process adopts a flexible deformation process without core mold spinning, so that there is a large degree of freedom in the deformation process of the blank, thereby preventing the occurrence of cracks.

Shape correction process: Correct the dimensional accuracy of the corrugated section of the workpiece through shape correction spinning. Since the flexible deformation process of the second process corrugated forming process gives the blank a high degree of freedom, it is easy to cause deviations in the dimensional accuracy of the blank, especially in the fillet area, so the shape correction process can ensure the dimensional accuracy of the final part. The amount of deformation in this shaping process is small, mainly concentrated in the fillet area.

The above-mentioned three-pass spinning process avoids the complicated process steps such as "grooving-rolling-rolling-welding" in the current traditional forming method of bellows, and there are longitudinal and transverse welds on the formed finished product. The disadvantage, as shown in Figure 8, is that the bellows currently made by the traditional tailor welding process have obvious welds on the surface and are sensitive to cracks. The use of the three-pass bellows forming spinning process described in the present invention not only ensures the dimensional accuracy of the final formed part, but also realizes the integrated plastic forming of the bellows in the whole process, so that it can undergo plastic work hardening and improve the final forming. The mechanical properties of the workpiece, as shown in Figure 9, is the bellows formed by the spinning method of the present invention. It can be seen that the spinning method realizes its overall forming without splicing cracks.

Description of drawings

Fig. 1 is a schematic diagram of a corrugated pipe, wherein Fig. 1a is a front view of a corrugated pipe, and Fig. 1b is a partial schematic diagram of area A of the corrugated section;

Fig. 2 is a structural schematic diagram of a spinning mechanism for forming bellows, wherein Fig. 2a is a front view, and Fig. 2b is a right view of Fig. 2a;

Fig. 3 is a schematic diagram of cylindrical member thinning and spinning assembly in step one;

Figure 4 is a schematic diagram of corrugated forming spinning assembly in the second step, wherein Figure 4a is a front view of the assembly and a schematic diagram of the wheel track, and Figure 4b is a partial schematic diagram of the forming surface of the wheel for forming corrugations and the area C of the wheel track;

Fig. 5 is a schematic diagram of the shape-correcting spinning assembly in step 3, wherein Fig. 5a is a front view of the assembly, and Fig. 5b is a partial schematic diagram of the forming surface of the shape-correcting wheel and the D area of the corrugated mandrel;

Figure 6 is a front view of the mandrel;

Fig. 7 is a schematic diagram of a bearing end cover, wherein Fig. 7a is a front view and Fig. 7b is a side view.

Fig. 8 is a corrugated pipe made by tailor welding in the prior art.

Fig. 9 is a bellows made by the present invention. In the picture:

1. Mandrel; 2. Hexagonal screw; 3. Clamp block; 4. Blank; 5. Straight wall mandrel; 6. Cylindrical powerful spinning wheel; 7. Hexagonal screw; 8. Mandrel end cover; 9. 10. Corrugated mandrel; 11. Shaping wheel; 12. Mandrel clamp block installation boss; 13. Mandrel blank fixed section; 14. Mandrel matching section; 15. Connection hole.

detailed description:

This embodiment is a spinning mechanism for forming bellows.

The formed bellows are LF3 aluminum alloy pipe fittings. The shape of the bellows is composed of straight wall sections and corrugated sections alternately. The outer diameter of the straight wall section is 370mm, and the wall thickness is 5mm. _The height H of the corrugation is 20mm, the root fillet radius R1 _of the outer surface of the corrugated section is 7mm, the top fillet radius R2 of the outer surface is 25mm, the root fillet radius _r1 of the inner surface of the corrugated section is 12mm, and the top fillet radius of the inner surface is r ₂ is 20mm, and the wall thickness t is 5mm.

This embodiment includes a mandrel 1, four clamping blocks 3, a straight wall mandrel 5, a corrugated mandrel 10, a mandrel end cover 8, a rotary wheel 6 for powerful spinning, a rotary wheel 9 for forming corrugations, and a correcting rotary wheel 11. Wherein: the mandrel is set on the mandrel 1, the blank 4 is set on the mandrel, and fixed by four clamping blocks 3 located at one end of the mandrel 1. The mandrel is divided into a straight wall mandrel 5 and a corrugated mandrel 10 . In forming bellows, different mandrels are selected according to different processes.

The mandrel 1 is a three-stage stepped shaft, which respectively forms a clamp block installation boss section 12 , a billet fixing section 13 and a mandrel matching section 14 . Threaded holes for connecting with the spinning machine are evenly distributed on the end face of the mandrel at one end of the clamp block installation boss section, and threaded holes for installing the mandrel end cover 8 are evenly distributed on the end face of the mandrel at one end of the mandrel mating section.

The clamp block installation boss section of the mandrel 1 has the largest outer diameter and is located at one end of the mandrel 1 . A threaded hole for installing the clamp block is opened on the outer peripheral surface of the clamp block installation boss 12 . In this embodiment, the outer diameter of the clamp block mounting boss section of the mandrel 1 is 450 mm, and the axial length is 150 mm.

The blank fixing section 13 is located in the middle of the mandrel. The outer diameter of the blank fixed section is slightly smaller than the clamp block installation boss 12, and the end surface of the step between the blank fixed section and the clamp block installation boss section forms a blank positioning surface. On the end face of the step between the blank fixing section and the mandrel matching section 14, two threaded holes for connecting the mandrel are symmetrically opened. In this embodiment, the outer diameter of the billet fixing section is 400 mm, and the axial length is 150 mm.

The mandrel matching section 14 is located at the other end of the mandrel 1, and four threaded holes for installing the mandrel end cap are evenly distributed on the end surface of the mandrel matching section. In this embodiment, the outer diameter of the mandrel fitting section is 340 mm, the inner diameter is 260 mm, and the axial length is slightly longer than that of the bellows forming part, which is 650 mm.

There are four clamping blocks 3, all of which are lath-shaped, and the lower surface of each clamping block 3 is an arc surface. The curvature of the lower surface of each clamping block is respectively the same as the curvature of the mounting boss section of the clamping block and the curvature of the blank.

Four clamping blocks 3 are evenly distributed and fixed on the outer circumferential surface of the mounting boss section of the clamping block, and the lower surface of each clamping block 3 is fitted with the outer circumferential surface of the mounting boss section of the clamping block; each clamping block 3 The other end is fixed at the blank fixed section place of mandrel, and makes the spacing that is used to lay blank between each clamp block 3 lower surfaces and the blank fixed section outer peripheral surface of mandrel. When in use: set the straight wall mandrel 5 or the corrugated mandrel 10 on the billet fixed section of the mandrel, fix the mandrel end cover 8 on the end face of the mandrel mating section of the mandrel, so that the straight wall mandrel 5 or the corrugated mandrel 10 is fixed with the mandrel. Set the blank on the outer peripheral surface of the straight wall mandrel 5 or the corrugated mandrel 10, and make the end surface of the positioning end of the blank fit the blank positioning surface on the mandrel. Four clamping blocks 3 are installed, and the lower surface of each clamping block is attached to the outer peripheral surface of the blank fixing section, thereby fixing the blank.

In this embodiment, the straight-wall mandrel 5 is tubular, the inner diameter of the straight-wall mandrel is 340 mm, and the outer diameter is 400 mm.

The corrugated mandrel 10 is a split mandrel structure, which adopts a common radial combination form, that is, several split dies are used to form the required mandrel shape. After the spinning is completed, the bellows and the corrugated mandrel are rotated together Remove it from the press, take out the split molds in sequence after taking out the key petals, so as to remove the bellows. The shape and size of the outer surface of the corrugated mandrel 10 are the same as the shape and size of the inner surface of the bellows, and are used for precisely forming the shape of the inner surface of the bellows. Therefore, the corrugated mandrel 10 is also composed of straight wall sections and corrugated sections alternately, wherein each corrugated section is composed of three sections of arcs, namely the top arc and two root arcs, and the radius of the arcs satisfies the formula (1) :

rm ₁ =r ₁ =R ₁ +t (1)

rm ₂ =r ₂ =R ₂ +t

Among them, rm ₁ is the radius of the arc at the root of the corrugated section of the corrugated mandrel, and rm ₂ is the radius of the arc at the top of the corrugated section of the corrugated mandrel. r ₁ is the fillet radius at the root of the corrugated section on the inner surface of the bellows, and r ₂ is the fillet radius at the top of the corrugated section on the inner surface of the bellows. R ₁ is the fillet radius at the root of the corrugated section on the outer surface of the bellows, and R ₂ is the fillet radius at the top of the corrugated section on the outer surface of the bellows. t is the wall thickness of the bellows.

In this embodiment, the arc radius rm ₁ at the root of the corrugated section of the corrugated mandrel 10 is 12 mm, and the arc radius rm ₂ at the top of the corrugated section of the corrugated mandrel 10 is 20 mm.

The mandrel end cover 8 is a ring-shaped plate, and two groups of connection holes 15 are evenly distributed in the ring on the end surface of the mandrel end cover 8, wherein one set of connection holes is located at the outer edge of the end surface of the mandrel end cover. It is used to fixedly connect the mandrel end cover 8 with the end face of the straight wall mandrel 5 or the corrugated mandrel 10; another set of connecting holes is located at the inner edge of the end surface of the mandrel end cover, and is used to The cover 8 is fixedly connected to the end face of the mandrel 1 . In this embodiment, the outer diameter of the mandrel end cover 8 is 396 mm, and the inner diameter is 180 mm. The center of the shaft end cover is 184mm, and the hole center of the connection hole for fixedly connecting the mandrel end cover 8 with the end surface of the mandrel 1 is 147mm from the center of the mandrel end cover.

The rotary wheel 6 for powerful spinning adopts an ordinary double-cone rotary wheel, that is, the forming surface of the rotary wheel is composed of two conical surfaces, and the two conical surfaces are transitioned by an arc. In this embodiment, the radius of the arc is 5mm, and the cone angle of the spinner, that is, the forming angle, is 30 ⁰ .

The roller forming surface of the roller 9 for forming the corrugation is divided into three arc sections, which are the middle arc section rs ₁ and the two end arc sections rs ₂ respectively, and the radius of each arc section satisfies formula (2):

rs ₁ < R ₁

rs ₂ >R ₂ (2)

Among them, rs ₁ is the fillet radius of the middle arc section of the roller forming surface, and rs ₂ is the fillet radius of the arc sections at both ends of the roller forming surface.

The arc section rs ₁ in the middle of the rotary wheel is 3-4 mm smaller than the root fillet radius R ₁ of the outer surface of the bellows, and the arc section rs ₂ at both ends of the rotary wheel is 3-4 mm larger than the top fillet radius R ₂ of the outer surface of the bellows .

In this embodiment, the fillet radius rs ₁ of the arc section in the middle of the roller forming surface is 4 mm, and the fillet radius rs ₂ of the arc sections at both ends of the roller forming surface is 28 mm.

The roller forming surface of the roller ₁₁ for correcting the shape is groove-shaped. The arc radius rb ₂ in the middle of the zone, and the arc radius rb ₃ at the end of the forming surface of the rotary wheel. The rotary wheel is used to precisely form the outer surface of the corrugated section of the corrugated pipe. , as shown in formula (3):

rb ₁ =R ₁

rb ₂ =R ₂ (3)

rb ₃ ≈ rb ₁

Among them, rb ₁ is the arc radius of the root of the groove area of the roller forming surface, rb ₂ is the radius of the arc in the middle of the groove area of the roller forming surface, and rb ₃ is the radius of the arc at the end of the roller forming surface.

In this embodiment, the arc radius rb ₁ at the root of the groove area of the roller forming surface is 7 mm, the arc radius rb ₂ in the middle of the groove area of the roller forming surface is 25 mm, and the arc radius rb ₃ at the end of the roller forming surface is 7 mm .

The four clamping blocks 3 are distributed on the clamping block installation boss 12 of the mandrel 1 at an angle of 90°, and the clamping blocks 3 are installed on the mandrel 1 through the hexagonal screws 2; The extrusion effect is fixed on the billet fixing section 13 of the mandrel 1, so as to realize the synchronous rotation of the billet 4 and the mandrel 1; one of the corrugated mandrel 10 and the straight wall mandrel 5 can be set on the mandrel matching section of the mandrel 1 14 on. One side end surface of the corrugated mandrel 10 can be connected with the mandrel end cover 8 through the hexagonal screw 7, and the other side end surface can be installed on the side end surface of the mandrel blank fixing section 13 through the hexagonal screw. One side end surface of the straight wall mandrel 5 can also be connected with the mandrel end cover 8 through the hexagon screw 7 . The mandrel end cover 8 is respectively connected with the side end surfaces of the mandrel 1 and the mandrel 5 or 10 through the hexagonal screws 7 , so as to realize the synchronous rotation of the mandrel 5 or 10 and the mandrel 1 .

This embodiment also proposes a method for forming a bellows by using the spinning mechanism for forming the bellows, which includes three steps, that is, three times of spinning. The first step is the thinning spinning process of the cylindrical part, the second step is the corrugation forming spinning process, and the third step is the corrugation correcting spinning process. The specific process is:

Step 1, thinning and spinning the cylindrical part. The workpiece is thinned and spun by the conventional spinning thinning method. Specifically, the cylindrical blank 4 is fixed by the clamp block 3 to realize the synchronous rotation of the blank 4 and the mandrel 1 . The straight wall mandrel 5 is adopted and the straight wall mandrel 5 is installed on the mandrel 1 through the mandrel end cover 8 so as to realize the synchronous rotation of the straight wall mandrel 5 and the mandrel 1 . Adopt three powerful spinning rollers 6 and make it evenly distributed with 120 ° of included angles along the circumferential direction. The rotary wheel track adopts axial linear feed so as to realize the thinning of the wall thickness of the cylindrical blank 4 . In this embodiment, the rotational speed of the mandrel 1 is 90r/min, the feed speed of the rotary wheel 6 is 1mm/r, and the axial feed length is slightly larger than the length of the workpiece. Give a length of 655mm.

Step 2, corrugated forming and spinning. The process of corrugation forming and spinning adopts coreless die-reducing spinning. The straight-wall mandrel installed in the spinning mechanism is removed, and the three powerful spinning wheels are replaced with the wheel 9 for forming corrugations. The track of the rotary wheel adopts the track line similar to the shape of the bellows, that is, the track line of the rotary wheel 9 for forming corrugations is also composed of corrugated lines and straight lines alternately, and the corrugated section of the track is composed of three arcs, which are respectively the top arc rp ₁ and two root arcs rp ₂ , as shown in Fig. 4a, the arc radius satisfies formula (4):

rp ₁ =R ₁ -rs ₁

(4)

rp ₂ =R ₂ +rs ₁

In the formula, rp ₁ is the arc radius of the root of the corrugated section in the wheel track, and rp ₂ is the arc radius of the top of the corrugated section in the wheel track. On the basis of the thin-walled cylindrical member formed in the first step, in this step, a corrugated shape can be formed on the cylindrical wall by using the roller for forming corrugations and the track line as described above.

The distance between the trajectory of the rotary wheel 9 and the contour of the bellows is rs ₁ .

In the present embodiment, the radius rp1 of the arc at the root of the corrugated line in the wheel track is 3mm, the arc radius _rp2 at the top of the corrugated line in the track of the wheel wheel is 29mm, and the rotating speed of the mandrel ₁ is 90r/min. The total axial feed length is slightly greater than the length of the workpiece. On the basis of the thin-walled cylindrical part formed in the first step, this step forms a corrugated shape on the cylindrical wall by using the roller 9 for forming corrugations and the track line as described above.

Step 3, the corrugation shaping and spinning process. Since the step 2 process belongs to core-less shrinking spinning, the dimensional accuracy of the formed corrugated section is poor. It is necessary to accurately calibrate the shape of the formed corrugation through the shape-correcting spinning process to meet the dimensional accuracy requirements of the finished product. . In this step, the workpiece formed in step 2 needs to be unloaded first, and the split corrugated mandrel 10 is installed inside the workpiece, and finally the corrugated mandrel 10 and the workpiece are set together on the core mold installation section 14 of the mandrel 1 Connect the corrugated mandrel 10 with the mandrel end cover 8 and the side end surface of the mandrel 1 blank fixed section 13 with hexagonal bolts, and then fix the workpiece with the clamp block 3, so as to realize the synchronization of the workpiece, the corrugated mandrel 10 and the mandrel 1 turn. The rotational speed of the mandrel 1 is 60r/min. The three rotary wheels use the correcting rotary wheel 11, and make the rotary wheel 11 carry out radial linear feed for each section of corrugation and the transition between the section of corrugation and the straight section, so that the outer surface of the corrugated section of the workpiece can be precisely formed through the rotary wheel forming surface. The size of the surface is precisely shaped by the support of the corrugated mandrel 10 to accurately shape the size of the inner surface of the corrugated section of the workpiece, and finally achieve the purpose of calibrating the overall shape and dimension accuracy of the corrugated section of the workpiece.

Claims (5)

1. A spinning mechanism for forming bellows, characterized in that it comprises a mandrel, a mandrel, a clip, a corrugated mandrel, a mandrel end cover, a wheel for forming corrugations, and a shape-correcting wheel; wherein: The mandrel is set on the mandrel, the blank is set on the mandrel, and fixed by four clamps at one end of the mandrel; the mandrel is divided into a straight wall mandrel and a corrugated mandrel, and in the forming bellows, Choose different core molds according to different processes; The corrugated mandrel is a split mandrel, the shape and size of the outer surface of the corrugated mandrel are the same as the shape and size of the inner surface of the corrugated pipe; and two root arcs, the radius of each arc satisfies formula (1): $\begin{array}{c}{\mathrm{<span\; class="notranslate">\; rm</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; t</span>}\\ {\mathrm{<span\; class="notranslate">\; rm</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; t</span>}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ Among them, rm ₁ is the radius of the arc at the root of the corrugated section of the corrugated mandrel, and rm ₂ is the radius of the arc at the top of the corrugated section of the corrugated mandrel; r ₁ is the radius of the arc at the root of the corrugated section on the inner surface of the bellows, and r ₂ is the radius of the arc at the top of the corrugated section on the inner surface of the bellows; R ₁ is the radius of the arc at the root of the corrugated section on the outer surface of the bellows, and R ₂ is the radius of the arc at the top of the corrugated section on the outer surface of the bellows; t is the wall thickness of bellows; There are four clamp blocks, and the lower surface of each clamp block is an arc surface; the curvature of the arc surface is the same as the curvature of the matching clamp block mounting boss section and the curvature of the blank. 2. A spinning mechanism for forming corrugated tubes according to claim 1, wherein the mandrel is a three-stage stepped shaft, which respectively forms the clamp block installation boss section, the blank fixing section and the core Die fitting section; wherein, the blank fixed section is located in the middle of the mandrel; the outer diameter of the blank fixed section is slightly smaller than the clamp block installation boss, and the end surface of the step between the blank fixed section and the clamp block installation boss section forms a blank positioning surface; Two threaded holes for connecting the core mold are symmetrically opened on the end face of the step between the blank fixing section and the mandrel matching section. 3. A spinning mechanism for forming corrugated pipes as claimed in claim 1, wherein the forming surface of the rotary wheel for forming corrugations is divided into three arc segments, which are the middle arc segment and two arc segments respectively. end arc, The radius of each arc segment satisfies formula (2): rs ₁ < R ₁ rs ₂ >R ₂ (2) Among them, rs ₁ is the arc radius of the middle arc section of the roller forming surface, and rs ₂ is the arc radius of the arc sections at both ends of the roller forming surface; The arc radius rs ₁ of the arc section in the middle of the roller forming surface is 3-4 mm smaller than the arc radius R ₁ at the root of the corrugated section on the outer surface of the bellows, and the arc radius rs ₂ of the arc sections at both ends of the roller forming surface is smaller than that of the bellows The arc radius R2 at the top of the corrugated section _on the outer surface is 3-4mm larger. 4. A spinning mechanism for forming bellows as claimed in claim 1, characterized in that the forming surface of the rotating wheel for correcting the shape is groove-shaped, and the forming surface of the rotating wheel is divided into three arc segments , which are the root arc of the groove area of the roller forming surface, the middle arc of the groove area of the roller forming surface, and the end arc of the roller forming surface. The roller is used to precisely shape the outer surface of the corrugated pipe section. The size is the same as the shape and size of the corrugated section on the outer surface of the bellows and coincides with each other, as shown in formula (3): $\begin{array}{c}{\mathrm{<span\; class="notranslate">\; rb</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; rb</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\mathrm{<span\; class="notranslate">\; rb</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&ap;</span>{\mathrm{<span\; class="notranslate">\; rb</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$ Among them, rb ₁ is the arc radius of the root of the groove area of the roller forming surface, rb ₂ is the radius of the arc in the middle of the groove area of the roller forming surface, and rb ₃ is the radius of the arc at the end of the roller forming surface. 5. A spinning method utilizing the spinning mechanism for forming bellows according to claim 1, characterized in that, the specific process is: Step 1, thinning and spinning the cylindrical workpiece; using the conventional spinning and thinning method to carry out thinning and spinning on the cylindrical workpiece; specifically, fixing the blank by clamping blocks to realize the synchronous rotation of the blank and the mandrel; using a straight-wall core The straight-wall mandrel is installed on the mandrel through the mandrel end cover to realize the synchronous rotation of the straight-wall mandrel and the mandrel; three powerful spinning wheels are used to make it uniform at an angle of 120° along the circumference Distribution; the rotary wheel track adopts axial linear feed; the mandrel speed is 90r/min, the rotary wheel feed speed is 1mm/r, and the axial feed length is slightly greater than the length of the workpiece; a thinned cylindrical workpiece is obtained; Step 2, corrugation forming and spinning; the process of corrugation forming and spinning adopts coreless die reduction spinning; remove the straight wall mandrel in the spinning mechanism, and replace three powerful rollers with three forming corrugations Spinning rotary wheel; the track of the rotary wheel is similar to the shape of the bellows; the corrugated section of the track is composed of three arcs, which are the top arc and two root arcs, and the radius of the top arc and the radius of the root arc satisfy the formula (4): $\begin{array}{c}{\mathrm{<span\; class="notranslate">\; rp</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; rs</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; rp</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; rs</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$ In the formula, rp ₁ is the arc radius at the root of the corrugated section in the wheel track, and rp ₂ is the arc radius at the top of the corrugated section in the wheel track; The distance between the trajectory of the rotary wheel for forming corrugations and the shape of the bellows is rs ₁ ; Spinning the cylindrical workpiece formed in step 1 by corrugation forming, and forming a corrugated shape on the surface of the cylindrical workpiece by spinning; Step 3, the corrugated shape correction and spinning process; put the split corrugated mandrel into the corrugated cylindrical workpiece; put the corrugated mandrel and the workpiece together on the mandrel installation section of the mandrel 1, and pass the core The shaft end cover fixes the corrugated mandrel and the mandrel, and fixes the cylindrical workpiece through the clamp block, so as to realize the synchronous rotation of the workpiece, the corrugated mandrel and the mandrel; replace the three correcting wheels with three The rotary wheel is used to form the corrugation; the rotation speed of the mandrel is set to 60r/min; each section of the corrugation and the transition between the section of corrugation and the straight section are fed radially and linearly through three shaping rotary wheels to obtain precise forming The corrugated section of the cylindrical workpiece; So far, the spinning forming of the bellows has been completed.