CN108746332B

CN108746332B - Tension-compression combined type plate stretch forming machine

Info

Publication number: CN108746332B
Application number: CN201810839183.4A
Authority: CN
Inventors: 付文智; 林琳; 李明哲; 刘英男
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2018-07-27
Filing date: 2018-07-27
Publication date: 2020-05-26
Anticipated expiration: 2038-07-27
Also published as: CN108746332A

Abstract

The invention discloses a tension-compression combined type plate stretch forming machine, which is plastic processing equipment for stretch forming of plate three-dimensional curved surface parts and belongs to the field of mechanical engineering. The device aims to simplify a hydraulic and electric control system of the device so as to reduce the manufacturing cost, and eliminate the bending force brought to the plate when a vertical oil cylinder on the conventional clamping device is loaded, so that the tensile stress and strain distribution of the tensile part are more uniform, and the shape stability and the material utilization rate of the formed part are improved. The stretch forming machine mainly comprises a frame, a guide device, a pressing device, a clamping device and a horizontal pre-stretching device (shown in the figure). The frame and the guide device support the pressing device, the clamping device and the horizontal pre-stretching device at two sides; the clamping device and the pressing device respectively consist of a plurality of clamping mechanisms and pressing mechanisms, and the clamping mechanisms and the pressing mechanisms are respectively arranged in a row on two sides of the die; the horizontal pre-stretching device consists of four hydraulic oil cylinders and universal joints and is arranged on the guide devices on two sides.

Description

Tension-compression combined type plate stretch forming machine

Technical Field

The invention discloses a tension-compression combined type plate stretch forming machine, which is plastic processing equipment for forming plate three-dimensional curved surface parts and belongs to the field of mechanical engineering.

Background

The stretch forming machine is widely used for forming double-curvature skin parts in the fields of aerospace, high-speed rail, ships and the like because the stretch forming machine has the specific advantages that the inner layer and the outer layer of the plate generate tensile stress and tensile strain in the stretching direction so as to reduce the rebound of a workpiece. When the traditional stretch forming machine is used for forming double-curvature skin pieces, the transverse tensile stress and tensile strain of the plate are obviously and unevenly distributed, the defects of wrinkling, tension cracking and the like are easily generated, a large transition area allowance is needed, the material utilization rate is extremely low, and meanwhile, the requirement on the precision of equipment is high, so that a control system is complex and the equipment is expensive. Although the currently used stretch forming machine improves the uniformity of the distribution of tensile stress and strain during the stretch forming of the sheet material to a certain extent, the hydraulic control system and the electrical control system are still complicated, the manufacturing cost is high, and the bending force brought to the sheet material when the sheet material is loaded by the vertical oil cylinder on the clamping device during the stretch forming cannot be eliminated, so the forming quality of the stretch forming member needs to be improved.

Disclosure of Invention

The invention provides a tension-compression combined type plate stretch forming machine, which replaces a clamping device consisting of an upper part and a lower part with a horizontal clamping device and a pre-stretching device, and aims to simplify a hydraulic and electric control system and eliminate the bending force brought to a plate when a vertical oil cylinder on the clamping device is loaded during the traditional stretch forming, so that the tensile stress and the strain distribution of the plate are more uniform, the forming quality and the material utilization rate of a complex curved surface part are improved, and the reduction of the manufacturing cost is realized.

The above object of the present invention is achieved as follows with reference to the accompanying drawings:

a draw-press composite plate stretch forming machine mainly comprises a frame 1, a guide device 2, a clamping device 3, a pressing device 4 and a horizontal pre-stretching device 7, wherein the clamping device 3, the pressing device 4 and the horizontal pre-stretching device 7 on the left side and the right side are supported by the frame 1 and the guide device 2; the clamping device 3 consists of a plurality of clamping mechanisms which are respectively arranged in a row at two sides of the die; the pressing device 4 consists of a plurality of pressing mechanisms which are respectively arranged in a row at two sides of the die; the horizontal pre-stretching device 7 consists of four hydraulic oil cylinders and universal joints, is arranged on the guide devices 2 on two sides of the frame 1, and is used for giving a pre-stretching force to the plate.

The distance between the clamping device 3, the hold-down device 4 and the horizontal pretensioning device 7 on the left and right sides of the machine frame is adjustable, and for the sake of convenience of adjustment, the guide device 2 as a part of the machine frame 1 is called a guide surface.

The clamping device 3 can adapt to the change of the shape of the plate material to move up and down in the grooves of the frame 1 and the guide device 2 in the stretching forming process.

The clamping mechanism mainly comprises a return spring 8, a clamp 9, a hinge rod 10 and a guide roller 11, wherein the clamp 9 comprises a clamping frame 14, a hydraulic cylinder 15, an upper clamping block 16 and a lower clamping block 17; the material clamping frame 14 and the hydraulic cylinder 15 are of an integrated or combined structure, the material clamping contact surfaces of the upper material clamping block 16 and the lower material clamping block 17 adopt a gripping plate type or plate flow type structure and are respectively fixed on a piston of the hydraulic cylinder 15 and the material clamping frame 14, and the clamp 9 is hinged with the hinge rod 10.

The return springs 8 are arranged on the hinged rods 10 between the clamps 9 and the rack 1, and are used for enabling the guide rollers 11 at the tail ends of the hinged rods 10 to be tightly attached to the guide devices 2 when the stretch forming machine does not work, so that the clamping devices 3 are enabled to return to the original positions.

The pressing mechanism consists of a roller 12, a pin 18, a bracket 19 and a hydraulic cylinder 20 and has a swinging function, and the roller 12 and the bracket 19 are connected through the pin 18 and have the function of adapting to the change of the curvature of the plate when acting force is applied to the plate.

The roller 12 is connected to the roller bracket 19 through the baffle 21 and the screw 22, and the roller 12 can rotate around the roller bracket 19 passively, so as to reduce the friction between the roller 12 and the plate.

The plurality of pressing mechanisms are connected together through the spring shaft 23, and the spring shaft is a steel wire flexible shaft, so that the actions of the pressing mechanisms tend to be flexibly synchronous;

the technical effects are as follows: compared with the traditional stretch forming machine, the stretch forming machine for the composite plate has the advantages that the used hydraulic control system and electric control system are greatly simplified, the operation and the maintenance are easy, and the flexible forming of the plate can be well realized; the application of the pressing device enables the loading path applied on the plate to be more reasonable, the tensile stress and strain distribution of the tensile piece to be more uniform, and the allowance of the transition area of the tensile piece is reduced. Compared with the prior plate stretching forming machine, the plate stretching forming machine has the advantages that the clamping device is redesigned, the horizontal pre-stretching device and the guide device are added, the movement mode and the acting force are changed, the bending force brought to the plate when the vertical oil cylinder on the clamping device is loaded in the traditional stretching forming process is eliminated, the uniformity of the tensile stress and the strain distribution is further improved, the forming quality of a complex curved surface part is greatly improved, and the manufacturing cost of the stretching forming machine is reduced.

Drawings

Fig. 1 is a schematic view of a stretch-forming machine: (a) is the front view of the drawing machine, (B) is the A-A section view of the drawing machine, and (c) is the B-B section view of the drawing machine;

FIG. 2 is a schematic view of a stretch-forming machine with an adjustment device;

FIG. 3 is a cross-sectional view of the clamp;

FIG. 4 is a schematic view of a hold-down mechanism having a rotating function;

fig. 5 is a schematic view of a roller structure with a rotation function: (a) is a front view, (B) is a sectional view A-A, and (c) is a sectional view B-B of (B);

FIG. 6 is a schematic view of a spherical curved part formed by connecting a plurality of pressing mechanisms together by using a steel wire flexible shaft: (a) is a front view, and (b) is an a-direction view of the front view.

FIG. 7 is a schematic view of the swinging of a row of grippers during the stretching process in the forming of spherical curved parts: fig. 7(a) shows the relative position of the clamp before the hold-down device is pressed down, and fig. 7(b) shows the relative position of the clamp at a certain time after the hold-down device is pressed down.

In the figure: 1. frame 2, guider 3, clamping device 4, push-down device 5, drawing die 6, curved surface piece 7, horizontal stretching device 8, reset spring 9, clamp 10, hinge rod 11, guide roller 12, running roller 13, adjusting device 14, clamping frame 15, hydraulic cylinder 16, upper clamping block 17, lower clamping block 18, pin 19, roller support 20, push-down mechanism hydraulic cylinder 21, baffle 22, screw 23, elastic shaft

The specific implementation mode is as follows:

the following describes the details and operation of the present invention with reference to the embodiments shown in the drawings.

The invention relates to a pressing device of a drawing and pressing combined type plate drawing forming machine, which is formed by arranging a plurality of pressing mechanisms in a row, wherein each pressing mechanism consists of a roller, a hydraulic cylinder, a pin and a bracket. In the process of stretch forming of the plate, the roller can generate a certain corner to adapt to the change of the plate by taking the pin as the center due to uneven deformation and double curvature deformation of each part of the plate. The clamping mechanism of the stretch forming machine consists of a clamp, a hinged rod, a return spring and a guide roller, wherein the clamp consists of a hydraulic cylinder, a material clamping frame, an upper material clamping block and a lower material clamping block, and is hinged with the hinged rod to form a row, so that the clamp has a head swinging function. The clamping device is used for clamping a plate, and then certain pre-tightening tension is applied to the plate, wherein the pre-tightening tension is from a horizontal pre-tensioning device and consists of four hydraulic oil cylinders and universal joints which are distributed at the edges of the left side and the right side of the guide device. The pressing device is used for applying certain pressure to the plate under the cooperation of the clamping device, the horizontal pre-stretching device and the drawing die so as to finally form the plate. In order to synchronize the actions of the individual press mechanisms of the press apparatus, each row of press mechanisms may be coupled together using a spring shaft. The invention adopts a hydraulic transmission mode to ensure that the pressing device and the clamping device adapt to the curvature change of the drawing die in the drawing process. When the plate is formed, the hydraulic pressure of the pressing device is adjusted, and when the hydraulic pressures of a plurality of hydraulic cylinders in the pressing device are the same, the rollers can generate different pressing quantities along the section shape of the drawing die, so that the tensile stress and strain distribution of the drawing piece are more uniform.

Fig. 1 is a schematic diagram of a drawing machine, in which a clamp 9 is powered by a hydraulic cylinder on the clamp, a roller 12 is powered by a hydraulic cylinder on a pressing mechanism, a clamping device 3 clamps a plate under the control of a row of hydraulic cylinders, a horizontal pre-tensioning device 7 gives a horizontal pre-tensioning force to the plate, the pulling force is from the reaction force of the pre-tensioning hydraulic cylinders and universal joints on a guide device 2, and a pressing device 4 contacts the plate through the roller 12 and applies certain pressure to the plate under the coordination of a drawing die 5 to form a curved part 6. During the stretch forming process, the clamping device 3 can move up and down on the frame 1 and the guide device 2 by using the guide roller 11 to adapt to the deformation of the plate. The hinged rod 10 between the clamp 9 and the frame 1 is provided with a return spring 8, and the function of the return spring is to enable a guide roller 11 at the tail end of the hinged rod to be in close contact with the guide device 2 before or after the stretching begins, so that the clamping device 3 is ensured to return to the original position.

Fig. 2 shows a drawing machine with an adjusting device 13 on the frame to adjust the distance between the left and right clamping devices and the pressing device to adapt to the forming of curved pieces with different length sizes. Considering the adaptability and the simplicity of operation, the guide means 2, which become part of the frame 1, are called guide surfaces, which move together under the control of the adjusting means 13. When the distance is adjusted, a hydraulic cylinder is used as an adjusting device, and the stroke of the frame 1 is controlled under the matching of the electromagnetic valve and the proximity switch. Fig. 3 is a schematic structural diagram of the clamp, which mainly comprises a clamping frame 14, a hydraulic cylinder 15 and

clamping blocks

16 and 17, wherein the clamping frame 14 and the hydraulic cylinder 15 are of an integrated structure. When the plate needs to be clamped, hydraulic oil is fed into the oil hole on the upper portion of the hydraulic cylinder 15, and hydraulic oil is discharged from the oil hole on the lower portion of the hydraulic cylinder, so that the hydraulic cylinder is controlled to drive the upper clamping block 16 to move downwards, and the upper clamping block and the lower clamping block 17 clamp the plate together. When the plate needs to be loosened, hydraulic oil enters the oil hole below the hydraulic cylinder 15, and hydraulic oil exits the oil hole above the hydraulic cylinder, so that the hydraulic cylinder 15 is controlled to drive the upper clamping block 16 to move upwards, and the plate is loosened after the upper clamping block is separated from the lower clamping block 17. The clamp 9 is hinged with the hinge rod 10, so that the clamp 9 has a swinging function and can adapt to the curvature change of the plate when clamping the plate.

Fig. 4 is a schematic view of a pressing mechanism with a swing function, which is composed of a roller 12, a pin 18, a bracket 19 and a hydraulic cylinder 20, wherein the roller 12 and the bracket 19 are coupled by the pin 18, so that the roller 12 has a swing function to be able to adapt to a change in curvature of a sheet when a force is applied to the sheet. Fig. 5 is a schematic view of a roller structure with a rotation function, in which the roller 12 can passively rotate around the roller bracket 19, so that friction between the roller 12 and the plate can be reduced, and the roller 12 and the roller bracket 19 are coupled by a baffle 21 and a screw 22. Fig. 6 is a schematic diagram of a forming spherical element formed by coupling a plurality of pushing mechanisms together by using elastic shafts 23, so that the actions of the pushing mechanisms tend to be flexibly synchronous, and the cross-sectional shapes of the pushing mechanisms are different when different shapes are formed. Fig. 7 is a schematic diagram of swinging of each clamp in a drawing process when a spherical curved surface piece is formed, after pre-stretching is finished, the arrangement of the clamps still keeps the straight edge shape of the plate, but the stress in the plate slightly exceeds the yield point, so that the subsequent deformation is facilitated. In the following drawing process, the clamp has the swinging function, so the clamp can swing in response to the curvature change of the plate, and meanwhile, each clamping mechanism can move up and down on the frame 1 and the guide device 2 to be matched with a formed target part.

The following illustrates the operation of the sheet stretch-forming machine. Firstly, the hydraulic oil cylinders of the pressing device and the clamping device are all retracted, and a guide roller at the tail end of each clamping mechanism is kept in close contact with a guide surface; then controlling a hydraulic cylinder on the clamping device to enable the clamp to clamp the plate, starting to enter hydraulic oil in a pre-tightening oil cylinder of the horizontal pre-tensioning device, and applying pre-tensioning tension to the plate through the reaction force of a universal joint connected to the pre-tightening oil cylinder on the guide device; and finally, applying a certain pressure to the plate through a pressing device, and under the matching of a clamping device and a drawing die, the plate generates enough tensile deformation, and finally, forming a three-dimensional curved surface piece according to a preset model surface attaching die. In the whole forming process, the hydraulic pressure of the hydraulic cylinder is controlled to control the deformation of the plate, the clamping device can move up and down on the guide device through the guide roller, the clamp is hinged with the hinge rod, so that the material clamping plate can adapt to the bidirectional curvature change of the plate, the bending force brought to the plate by the vertical oil cylinder during the loading of the upper clamping mechanism and the lower clamping mechanism in the drawing process is eliminated by the clamping device, and the drawing stress and the strain distribution of the drawing piece are more uniform under the cooperation of the pressing mechanism.

The stretching forming machine improves the traditional stretching forming machine, designs a more reasonable control mechanism on the basis of simplifying mechanical equipment and reducing the cost of a hydraulic control system and an electrical control system, eliminates redundant force acting on a plate material in the stretching forming process, enables the stress-strain distribution of a stretching part to be more uniform, effectively improves the quality of a complex stretching part, improves the material utilization rate and further reduces the cost again.

Claims

1. A stretch forming machine for a tension-compression composite plate mainly comprises a machine frame (1), a guide device (2), a clamping device (3), a pressing device (4) and a horizontal pre-stretching device (7), and is characterized in that the clamping device (3), the pressing device (4) and the horizontal pre-stretching device (7) on the left side and the right side are supported by the machine frame (1) and the guide device (2); the clamping device (3) consists of a plurality of clamping mechanisms which are respectively arranged in a row at two sides of the die; the pressing device (4) consists of a plurality of pressing mechanisms which are respectively arranged in a row at two sides of the die; the horizontal pre-stretching device (7) consists of four hydraulic oil cylinders and universal joints, is arranged on the guide devices (2) on two sides of the rack (1) and is used for giving a pre-stretching force to the plate;

the distances among the clamping devices (3), the pressing devices (4) and the horizontal pre-stretching devices (7) which are respectively positioned at the left side and the right side of the rack are adjustable, and for the convenience of adjustment, the guide devices (2) which are used as a part of the rack (1) are called as guide surfaces;

and each clamp of the clamping device (3) can adapt to the change of the shape of the plate to move up and down in the grooves of the rack (1) and the guide device (2) in the stretching forming process.

2. The stretch-forming machine for composite plates according to claim 1, wherein the clamping mechanism mainly comprises a return spring (8), a clamp (9), a hinged rod (10) and a guide roller (11), wherein the clamp (9) comprises a clamping frame (14), a hydraulic cylinder (15), an upper clamping block (16) and a lower clamping block (17); the material clamping frame (14) and the hydraulic cylinder (15) are of an integrated or combined structure, the material clamping contact surfaces of the upper material clamping block (16) and the lower material clamping block (17) are of a gripping plate type or plate flow type structure, the upper material clamping block (16) and the lower material clamping block (17) are respectively fixed on a piston of the hydraulic cylinder (15) and the material clamping frame (14), and the clamp (9) is hinged to the hinge rod (10).

3. A stretch-forming machine for stretch-forming composite sheet materials according to claim 2, characterised in that return springs (8) are provided on the articulated rods (10) between the clamps (9) and the frame (1) and act to bring the guide rollers (11) at the ends of the articulated rods (10) into close abutment with the guide means (2) when the stretch-forming machine is not in operation, ensuring that the holding means (3) returns to its original position.