CN113020388B

CN113020388B - Four-degree-of-freedom transverse skin stretcher

Info

Publication number: CN113020388B
Application number: CN202110172398.7A
Authority: CN
Inventors: 杨伟; 程军周; 浦文杰; 任玉成; 刘睿平; 张镭
Original assignee: China National Heavy Machinery Research Institute Co Ltd
Current assignee: China National Heavy Machinery Research Institute Co Ltd
Priority date: 2021-02-08
Filing date: 2021-02-08
Publication date: 2023-03-10
Anticipated expiration: 2041-02-08
Also published as: CN113020388A

Abstract

The invention belongs to the technical field of stretch forming, and particularly provides a four-degree-of-freedom transverse skin stretcher which comprises a left stretching unit, a right stretching unit and a fixed frame, wherein the left stretching unit and the right stretching unit are identical in structure and are bilaterally and symmetrically connected to the fixed frame; the left stretching unit comprises a back horizontal driving branch, a front vertical driving branch, a back vertical driving branch and a clamp, the skin stretcher has four degrees of freedom, can meet the requirement of stretching and forming of skin parts with smaller transverse curvature or gentle curvature change, and has the characteristics of simple structure, low equipment price, economy and practicality.

Description

Four-degree-of-freedom transverse skin stretcher

Technical Field

The invention belongs to the technical field of stretch forming, and particularly relates to a four-degree-of-freedom transverse skin stretcher.

Background

The stretching machine is special equipment for stretching and forming skin parts. The stretching machine can be generally divided into a transverse skin stretching machine and a longitudinal skin stretching machine, the transverse skin stretching machine is mainly used for forming a workpiece with small transverse curvature and single curvature or gentle curvature change, the workpiece is typically a FET-1200 type transverse skin stretching machine produced by french ACB company, the transverse skin stretching machine is in a bilateral symmetry structure, 4 branches are arranged on one side, 2 branches located in the horizontal direction are T (universal pair) C (cylindrical pair) R (revolute pair) R structures of 4 kinematic pairs, the other 2 branches located in the vertical direction are respectively TCT structures and RCR structures of 3 kinematic pairs, the control actuating cylinders driven by 8 hydraulic powers drive the control actuating cylinders, and the output is the motion of two clamps. The stretching machine is controlled by a numerical control system, has good performance and forming precision, but is expensive in equipment price, and is mainly applied to the field of aircraft manufacturing at the present stage. With the development of science and technology, large three-dimensional curved surface stretching pieces are increasingly applied to industries such as high-speed railways, automobiles, modern buildings and the like, however, the application of the transverse skin stretching machine in other fields is limited due to the fact that the existing transverse skin stretching machine is single in structure and expensive in equipment price.

Disclosure of Invention

The invention provides a four-degree-of-freedom transverse skin stretcher, which aims to solve the problems that in the prior art, a transverse skin stretcher is mainly applied to the field of aircraft manufacturing, the structure is single, the equipment price is high, and the application of the transverse skin stretcher in other fields is limited.

Therefore, the invention provides a four-degree-of-freedom transverse skin stretcher which comprises a left stretching unit, a right stretching unit and a fixed frame, wherein the left stretching unit and the right stretching unit have the same structure and are connected to the fixed frame in a bilaterally symmetrical manner; the left stretching unit comprises a back horizontal driving branch, a front vertical driving branch, a back vertical driving branch and a clamp, the clamp is longitudinally arranged, the front portion of the left side of the clamp is connected with the fixed rack through the front horizontal driving branch, the rear portion of the left side of the clamp is connected with the fixed rack through the back horizontal driving branch, the front portion of the lower end of the clamp is connected with the fixed rack through the front vertical driving branch, and the rear portion of the lower end of the clamp is connected with the fixed rack through the back vertical driving branch.

The rear horizontal driving branch comprises a first spherical hinge, a first moving pair and a first rotating pair, one end of the first moving pair is connected with the fixed rack through the first spherical hinge, and the other end of the first moving pair is connected with the clamp through the first rotating pair.

The front horizontal driving branch comprises a second spherical hinge, a second moving pair and a first universal hinge, one end of the second moving pair is connected with the fixed rack through the second spherical hinge, and the other end of the second moving pair is connected with the clamp through the first universal hinge.

The first universal hinge comprises a second revolute pair and a third revolute pair, and the other end of the second revolute pair is connected with the clamp through the second revolute pair and the third revolute pair in sequence.

The axis of the first rotating pair is parallel to the longitudinal axis of the clamp, the axis of the first rotating pair is collinear with the axis of the third rotating pair, the axes of the second moving pair, the second rotating pair and the third rotating pair are mutually vertical, and the central connecting line of the first spherical hinge and the second spherical hinge is parallel to the transverse axis of the fixed rack.

The front vertical driving branch comprises a third spherical hinge, a third moving pair and a fourth spherical hinge, one end of the third moving pair is connected with the fixed rack through the third spherical hinge, and the other end of the third moving pair is connected with the clamp through the fourth spherical hinge.

The rear vertical driving branch comprises a fourth revolute pair, a fifth spherical hinge and a fourth revolute pair, one end of the fourth revolute pair is connected with the fixed rack through the fifth spherical hinge, and the other end of the fourth revolute pair is connected with the clamp through the fourth revolute pair.

The axis of the fourth rotating pair is parallel to the transverse axis of the clamp, and the central connecting line of the third spherical hinge and the fifth spherical hinge is parallel to the transverse axis of the fixed rack.

The clamp comprises a plunger cylinder, a jaw body, a plunger, an upper jaw strip and a lower jaw strip, the number of the plunger cylinder, the plunger, the upper jaw strip and the lower jaw strip is multiple, a groove is formed in the right side of the jaw body from front to back, the plunger cylinders are sequentially connected to the upper portion of the groove at equal intervals from front to back, 1 plunger is installed in each plunger cylinder, the upper jaw strip is connected to the lower end of the plunger, and the lower jaw strip is connected to the lower portion of the groove and is oppositely arranged with the upper jaw strip.

The plunger cylinder and the jaw body are of an integrated structure.

The invention has the beneficial effects that: the invention provides a four-degree-of-freedom transverse skin stretcher, wherein a left stretching unit and a right stretching unit have the same structure and are bilaterally and symmetrically connected to a fixed frame, for a single-side stretching unit, a front horizontal driving branch, a rear horizontal driving branch, a front vertical driving branch and a rear vertical driving branch jointly constrain two moving degrees of freedom of the stretcher, so that a stretching mechanism has four degrees of freedom, namely three rotational degrees of freedom and one moving degree of freedom, and the stretching units (the left stretching unit and the right stretching unit) on two sides respectively enable an integral clamp clamping plate to be attached to a mold tangentially under the action of the two horizontal driving branches (the front horizontal driving branch and the rear horizontal driving branch) and the two vertical driving branches (the front vertical driving branch and the rear vertical driving branch) during stretching, are mainly used for forming skin workpieces with smaller transverse curvature and are applied to industries such as airplanes, high-speed railways, automobiles, modern buildings and the like; the four-degree-of-freedom transverse skin stretcher is simple in structure, low in equipment price, economical and practical.

Drawings

The present invention will be described in further detail below with reference to the accompanying drawings.

FIG. 1 is a schematic perspective view of a four degree-of-freedom cross-skin stretcher;

FIG. 2 is a front view of a four degree-of-freedom cross-skin stretcher;

FIG. 3 is a top view of a four degree-of-freedom cross-skin stretcher;

FIG. 4 is a structural left side view of a four degree-of-freedom cross-skin stretcher;

figure 5 is a transverse cross-sectional view of the clamp.

Description of the reference numerals: 1. fixing the frame; 2. a third spherical hinge; 3. a third moving pair; 4. a fourth spherical hinge; 5. a fourth revolute pair; 6. a second spherical hinge; 7. a second sliding pair; 8. a first universal hinge; 9. a second revolute pair; 10. a third revolute pair; 11. a first spherical hinge; 12. a first moving pair; 13. a first rotating pair; 14. a fifth spherical hinge; 15. a fourth sliding pair; 16. a jaw body; 17. a plunger; 18. an upper jaw strip; 19. a lower jaw bar; 20. a plunger cylinder; i, horizontally driving a branch after the branch is formed; II, front horizontal driving branches; III, front vertical driving branch; IV, vertically driving the branch; v, clamping tongs.

Detailed Description

Example 1:

as shown in fig. 1-4, a four-degree-of-freedom transverse skin stretcher comprises a left stretching unit, a right stretching unit and a fixed frame 1, wherein the left stretching unit and the right stretching unit have the same structure, and are bilaterally and symmetrically connected to the fixed frame 1; left side stretching unit includes back horizontal drive branch I, preceding horizontal drive branch II, preceding vertical drive branch III, back vertical drive branch IV and clamp V, clamp V vertically sets up, the left side front portion of clamp V connects fixed frame 1 through preceding horizontal drive branch II, the left side rear portion of clamp V connects fixed frame 1 through back horizontal drive branch I, the lower extreme front portion of clamp V connects fixed frame 1 through preceding vertical drive branch III, the lower extreme rear portion of clamp V connects fixed frame 1 through back vertical drive branch IV.

The four-degree-of-freedom transverse skin stretcher provided by the invention has the advantages that the left stretching unit and the right stretching unit have the same structure, the rear horizontal driving branch I, the front horizontal driving branch II, the front vertical driving branch III and the rear vertical driving branch IV jointly constrain two moving degrees of freedom of the stretcher, so that the stretching mechanism has four degrees of freedom, namely three rotational degrees of freedom and one moving degree of freedom, and the stretching units (the left stretching unit and the right stretching unit) at two sides during stretching enable an integral clamping plate to cling to a mold tangentially under the action of the two horizontal driving branches (the rear horizontal driving branch I, the front horizontal driving branch II) and the two vertical driving branches (the front vertical driving branch III and the rear vertical driving branch IV) respectively, so that the integral clamping plate is mainly used for forming a skin type workpiece with smaller transverse curvature.

Example 2:

on the basis of embodiment 1, the rear horizontal driving branch i includes a first spherical hinge 11, a first moving pair 12 and a first rotating pair 13, one end of the first moving pair 12 is connected to the fixed frame 1 through the first spherical hinge 11, and the other end is connected to the clamp v through the first rotating pair 13. The rear horizontal driving branch I formed by combining the first spherical hinge 11, the first moving pair 12 and the first rotating pair 13 is simple in structure, economical and practical on the basis of guaranteeing the flexible rotation of the driving clamp V.

Furthermore, the front horizontal driving branch II comprises a second spherical hinge 6, a second moving pair 7 and a first universal hinge 8, one end of the second moving pair 7 is connected with the fixed rack 1 through the second spherical hinge 6, and the other end of the second moving pair 7 is connected with the clamp V through the first universal hinge 8. The front horizontal driving branch II of the combination of the second spherical hinge 6, the second sliding pair 7 and the first universal hinge 8 is simple in structure, economical and practical on the basis of ensuring that the driving clamp V rotates flexibly.

Further, the first universal hinge 8 comprises a second revolute pair 9 and a third revolute pair 10, and the other end of the second revolute pair 7 is connected with the clamp V sequentially through the second revolute pair 9 and the third revolute pair 10. The structure has high flexibility when rotating.

Furthermore, the axis of the first revolute pair 13 is parallel to the longitudinal axis of the clamp V, the axes of the first revolute pair 13 and the third revolute pair 10 are collinear, the axes of the second revolute pair 7, the second revolute pair 9 and the third revolute pair 10 are mutually vertical, and the central connecting line of the first spherical hinge 11 and the second spherical hinge 6 is parallel to the transverse axis of the fixed rack 1. By the arrangement, the horizontal driving branches (the front horizontal driving branch II and the rear horizontal driving branch I) restrain the clamp from moving transversely along the fixed rack.

Example 3:

on the basis of the embodiment 2, the front vertical driving branch iii comprises a third spherical hinge 2, a third moving pair 3 and a fourth spherical hinge 4, wherein one end of the third moving pair 3 is connected with the fixed frame 1 through the third spherical hinge 2, and the other end of the third moving pair is connected with the clamp v through the fourth spherical hinge 4. The front vertical driving branch III of the combination of the third spherical hinge 2, the third sliding pair 3 and the fourth spherical hinge 4 has simple structure, economy and practicality on the basis of ensuring the flexible rotation of the driving clamp V.

Furthermore, the rear vertical driving branch iv comprises a fifth spherical hinge 14, a fourth sliding pair 15 and a fourth revolute pair 5, one end of the fourth sliding pair 15 is connected with the fixed frame 1 through the fifth spherical hinge 14, and the other end of the fourth sliding pair 15 is connected with the clamp v through the fourth revolute pair 5. The rear vertical driving branch IV formed by combining the fifth spherical hinge 14, the fourth sliding pair 15 and the fourth revolute pair 5 is simple in structure, economical and practical on the basis of ensuring that the driving clamp V rotates flexibly.

Furthermore, the axis of the fourth revolute pair 5 is parallel to the transverse axis of the clamp V, and the central connecting line of the third spherical hinge 2 and the fifth spherical hinge 14 is parallel to the transverse axis of the fixed rack 1. With this arrangement, the vertical drive legs (front vertical drive leg III and rear vertical drive leg IV) constrain the clamp from moving longitudinally along the fixed frame.

As shown in fig. 5, further, the pliers v comprises a plunger cylinder 20, a jaw body 16, a plunger 17, an upper jaw strip 18 and a lower jaw strip 19, wherein the plunger cylinder 20, the plunger 17, the upper jaw strip 18 and the lower jaw strip 19 are all provided in a plurality, a groove is formed in the right side of the jaw body 16 from front to back, the plunger cylinders 20 are sequentially connected to the upper part of the groove at equal intervals from front to back, 1 plunger 17 is installed in each plunger cylinder 20, the lower end of the plunger 17 is connected to the upper jaw strip 18, the lower part of the groove is connected to the lower jaw strip 19, and the upper jaw strip 18 and the lower jaw strip 19 are arranged oppositely. According to the thickness of the blank, the up-and-down movement position of the plunger 17 in the plunger cylinder 20 is controlled through hydraulic pressure, so that the upper jaw strip 18 and the lower jaw strip 19 clamp or loosen the blank, the material is conveniently clamped according to the requirement, the adaptability is high, the structure is simple, and the clamping is stable.

Further, the plunger cylinder 20 and the jaw body 16 are of an integral structure. The integrated structure has compact structure and large clamping force.

Furthermore, the first moving pair 12, the second moving pair 7, the third moving pair 3 and the fourth moving pair 15 are all driven by hydraulic cylinders. The hydraulic cylinder can conveniently realize stepless speed regulation, the speed regulation range is wide, the movement of the clamp is uniform and stable, no reversing impact is generated when the moving part is reversed, and the device has small volume, light weight, compact structure, simple operation and convenient adjustment and control under the condition of the same power.

The working principle of the four-degree-of-freedom transverse skin stretcher is as follows: firstly, a stretcher clamps two sides of a sheet material through clamps of a left stretching unit and a right stretching unit, and performs pre-stretching according to needs, and then, as the stretcher has four degrees of freedom, namely three rotational degrees of freedom and one degree of freedom of movement, four driving hydraulic cylinders (a first moving pair 12, a second moving pair 7, a third moving pair 3 and a fourth moving pair 15) in the left stretching unit and the right stretching unit on a fixed frame 1 are respectively controlled to perform coordinated actions so that the clamps can make corresponding swinging and rotation according to the curved surface shape of a die, and the sheet material is completely attached to a stretching die.

In the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by the terms "left", "right", etc., based on the orientation or positional relationship shown in the drawings, it is not intended to indicate or imply that the device or element referred to must have a particular orientation, configuration and operation in a particular orientation, and therefore the terms describing the positional relationship in the drawings are for illustrative purposes only and should not be construed as limiting the present invention.

The above examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims and any design similar or equivalent to the scope of the invention.

Claims

1. A four-degree-of-freedom transverse skin stretcher is characterized in that: the device comprises a left stretching unit, a right stretching unit and a fixed rack (1), wherein the left stretching unit and the right stretching unit have the same structure, and are bilaterally and symmetrically connected to the fixed rack (1); the left stretching unit comprises a rear horizontal driving branch (I), a front horizontal driving branch (II), a front vertical driving branch (III), a rear vertical driving branch (IV) and a clamp (V), the clamp (V) is longitudinally arranged, the front part of the left side of the clamp (V) is connected with the fixed rack (1) through the front horizontal driving branch (II), the rear part of the left side of the clamp (V) is connected with the fixed rack (1) through the rear horizontal driving branch (I), the front part of the lower end of the clamp (V) is connected with the fixed rack (1) through the front vertical driving branch (III), and the rear part of the lower end of the clamp (V) is connected with the fixed rack (1) through the rear vertical driving branch (IV); the rear horizontal driving branch (I) comprises a first spherical hinge (11), a first moving pair (12) and a first rotating pair (13), one end of the first moving pair (12) is connected with the fixed rack (1) through the first spherical hinge (11), and the other end of the first moving pair (12) is connected with the clamp (V) through the first rotating pair (13); the front horizontal driving branch (II) comprises a second spherical hinge (6), a second moving pair (7) and a first universal hinge (8), one end of the second moving pair (7) is connected with the fixed rack (1) through the second spherical hinge (6), and the other end of the second moving pair is connected with the clamp (V) through the first universal hinge (8); the front vertical driving branch (III) comprises a third spherical hinge (2), a third moving pair (3) and a fourth spherical hinge (4), one end of the third moving pair (3) is connected with the fixed rack (1) through the third spherical hinge (2), and the other end of the third moving pair (3) is connected with the clamp (V) through the fourth spherical hinge (4); the rear vertical driving branch (IV) comprises a fifth spherical hinge (14), a fourth moving pair (15) and a fourth rotating pair (5), one end of the fourth moving pair (15) is connected with the fixed rack (1) through the fifth spherical hinge (14), and the other end of the fourth moving pair (15) is connected with the clamp (V) through the fourth rotating pair (5).

2. The four degree-of-freedom transverse skin stretcher of claim 1, characterized in that: the first universal hinge (8) comprises a second revolute pair (9) and a third revolute pair (10), and the other end of the second revolute pair (7) is connected with the clamp (V) through the second revolute pair (9) and the third revolute pair (10) in sequence.

3. The four degree-of-freedom transverse skin stretcher of claim 2, characterized in that: the axis of the first revolute pair (13) is parallel to the longitudinal axis of the clamp (V), the axis of the first revolute pair (13) is collinear with the axis of the third revolute pair (10), the axes of the second revolute pair (7), the second revolute pair (9) and the third revolute pair (10) are mutually vertical, and the central connecting line of the first spherical hinge (11) and the second spherical hinge (6) is parallel to the transverse axis of the fixed rack (1).

4. The four degree-of-freedom transverse skin stretcher of claim 3, characterized in that: the axis of the fourth revolute pair (5) is parallel to the transverse axis of the clamp (V), and the central connecting line of the third spherical hinge (2) and the fifth spherical hinge (14) is parallel to the transverse axis of the fixed rack (1).

5. The four degree-of-freedom transverse skin stretcher of claim 4, characterized in that: the pliers (V) comprise plunger cylinders (20), jaw bodies (16), plungers (17), upper jaw strips (18) and lower jaw strips (19), the plunger cylinders (20), the plungers (17), the upper jaw strips (18) and the lower jaw strips (19) are in a plurality of numbers, the right sides of the jaw bodies (16) are provided with grooves from front to back, the plunger cylinders (20) are sequentially connected to the upper portions of the grooves at equal intervals from front to back, 1 plunger (17) is installed in each plunger cylinder (20), the upper jaw strips (18) are connected to the lower ends of the plungers (17), and the lower jaw strips (19) are connected to the lower portions of the grooves and the upper jaw strips (18) and the lower jaw strips (19) are arranged oppositely.

6. The four degree-of-freedom transverse skin stretcher of claim 5, characterized in that: the first moving pair (12), the second moving pair (7), the third moving pair (3) and the fourth moving pair (15) are driven by hydraulic cylinders.