CN211803411U - Pre-extension drawing die with functions of preventing damage and lateral force - Google Patents

Abstract

The utility model relates to a mould technical field specifically indicates a pre-extension drawing die with loss prevention and lateral force prevention function. Comprises a female die, a male die matched with the female die and a material pressing ring for pressing a sheet material; the pressing ring is provided with a lower movable pressing plate, and the female die is provided with an upper movable pressing plate; an auxiliary drawing mechanism is arranged between the male die and the lower movable pressure plate, and a convex part which is vertically and downwards convex is arranged on the upper movable pressure plate; the lower movable pressure plate is provided with a concave part for accommodating the convex part; and a centering mechanism for driving the upper movable pressure plate and the lower movable pressure plate to reset in the pressing process is arranged between the convex part and the concave part. The utility model can effectively offset the lateral force when the work stress area bears large working force by arranging the centering mechanism, thereby ensuring the pre-extension effect; and under the condition that the movable material pressing plate cannot reset, the damage risk caused by continuous closing of the die can be avoided through the centering mechanism.

Description

Pre-extension drawing die with functions of preventing damage and lateral force

Technical Field

The utility model relates to a mould technical field specifically indicates a pre-extension drawing die with loss prevention and lateral force prevention function.

Background

At present, the automobile market tends to be saturated in China, the competition of each large automobile brand is increasingly white and hot, and in addition, the increasingly severe environmental protection requirements are met, and a large problem currently faced by each automobile manufacturer is the cost reduction of a full value chain. For the outer covering part of the automobile body, on the premise of meeting the large quality of sheet materials, the improvement of the material utilization rate is the first requirement. In the traditional stamping process, measures such as optimizing process supplement surfaces, reducing drawing depth, optimizing layout and the like are usually adopted to improve the material utilization rate, the most common problem of the outer covering piece of the shallow drawing sheet is insufficient rigidity, the restlessness phenomenon of vehicle driving can be caused by the insufficient rigidity, the driving noise is increased, the problem of insufficient rigidity generated in stamping forming is avoided, the drawing depth is required to be not too shallow, and the bottleneck of improving the material utilization rate is brought.

In order to solve the technical problem, a pre-extension drawing die is proposed, and the Chinese invention patent with the patent number of CN201710507974.2 and named as a wedge type pre-extension drawing die comprises a female die, a male die matched with the female die and a pressure ring for pressing plates, wherein the pressure ring is provided with a lower movable pressure plate, the female die is provided with an upper movable pressure plate matched with the lower movable pressure plate, a synchronization mechanism is arranged between the upper movable pressure plate and the lower movable pressure plate, an auxiliary drawing mechanism is arranged between the lower movable pressure plate and the male die, the auxiliary drawing mechanism comprises an upper wedge guide plate arranged on the inner side surface of the lower movable pressure plate and a lower wedge guide plate arranged on the outer side surface of the male die, and the lower wedge guide plate is matched with the upper wedge guide plate; the lower part of the corresponding fitting surface of the upper wedge guide plate and the lower wedge guide plate is provided with a downward inclined surface, the upper part of the corresponding fitting surface of the lower wedge guide plate and the upper wedge guide plate is provided with a downward inclined surface, and the inclined angles of the inclined surfaces of the upper wedge guide plate and the lower wedge guide plate are equal; a movement gap is arranged between the upper inclined wedge guide plate and the lower inclined wedge guide plate; the synchronizing mechanism comprises an upper clamping key arranged on the upper movable pressure plate and a lower clamping key arranged on the lower movable pressure plate, a chamfer is arranged on the lower portion of the corresponding surface of the upper clamping key and the lower clamping key, a chamfer is arranged on the upper portion of the corresponding surface of the lower clamping key and the upper portion of the corresponding surface of the upper clamping key, and the chamfer direction of the upper clamping key and the chamfer direction of the lower clamping key are the same and the angle is equal.

When the die normally works, the female die moves downwards, the working stress area contacts and locks the plate, and the upper movable pressure plate and the lower movable pressure plate start to move towards the horizontal stretching direction under the action of the synchronizing mechanism along with the contact of the inclined planes of the upper wedge guide plate and the lower wedge guide plate until the die is closed. However, this structure has some problems:

1. the area where the pressure surface and the draw bead are located is a main working stress area, and the area bears great working force during pre-extension, so that the lower movable pressure plate and the upper movable pressure plate bear unilateral eccentric load, namely, the eccentric load can influence the locking effect of the plate during pre-extension;

2. under extreme working conditions, two groups of reset nitrogen cylinders of the pre-extension drawing die have the possibility of failure, for example, when the reset nitrogen cylinder of the upper movable pressure plate fails, the upper movable pressure plate cannot be pushed to the initial position by the upper reset nitrogen cylinder, so the upper movable pressure plate is no longer at the initial position, because the pressure surfaces and the draw beads of the working stress areas on the upper movable pressure plate and the lower movable pressure plate cannot be aligned, and the positioning plates arranged on the upper movable pressure plate and the lower movable pressure plate cannot be aligned with the positioning plates correspondingly arranged on the upper movable pressure plate in an idle opening manner, and the inside of the die is difficult to observe when the die is in operation, if the die is continuously closed in the state, the damage of the upper movable pressure plate and the lower movable pressure plate, namely the damage of the die, is.

Disclosure of Invention

The utility model aims at solving the defects of the prior art and providing a pre-extending drawing die with functions of loss prevention and lateral force prevention.

The technical scheme of the utility model is that: a pre-extension drawing die with the functions of preventing damage and lateral force comprises a female die, a male die matched with the female die and a material pressing ring for pressing a sheet material; an upper movable pressure plate and a lower movable pressure plate which are matched with each other are arranged on the pressure ring; an auxiliary drawing mechanism is arranged between the upper movable pressure plate and the lower movable pressure plate,

the method is characterized in that: the upper movable material pressing plate is provided with a bulge part which is vertically and downwards bulged; the lower movable pressure plate is provided with a concave part for accommodating the convex part; and a centering mechanism for driving the upper movable pressure plate and the lower movable pressure plate to reset in the pressing process is arranged between the convex part and the concave part.

The centering mechanism further comprises an upper centering mechanism for driving the upper movable pressure plate to reset; the upper centering mechanism comprises an upper centering guide plate arranged on one side of the lower end of the protruding part and a lower centering guide plate arranged on one side of the upper end of the recessed part and corresponding to the upper centering guide plate; the lower end of one side of the upper centering guide plate facing the lower centering guide plate is provided with a first inclined plane working surface which is vertically downwards inclined, and the upper end of the upper centering guide plate is provided with a vertical first straight working surface; the upper end of one side of the lower centering guide plate facing the upper centering guide plate is a second inclined working surface which is vertically inclined upwards and has the same inclination angle with the first inclined working surface, and the lower end of the lower centering guide plate is a second straight working surface corresponding to the first straight working surface.

The centering mechanism further comprises a lower centering mechanism for driving the lower movable pressure plate to reset; the lower centering mechanism comprises an upper clamping key arranged on the other side of the lower end of the convex part and a lower clamping key arranged on the other side of the upper end of the concave part and corresponding to the upper clamping key; the lower end of one side of the upper clamping key surface facing the lower clamping key is provided with a third inclined surface working surface which is vertically inclined downwards, and the upper end of the upper clamping key surface is provided with a vertical third straight surface working surface; the lower clamping key face is a fourth inclined face working face which is inclined upwards along the vertical direction and is equal to the inclination angle of the third inclined face working face, and the upper end of one side of the upper clamping key face is a fourth straight face working face corresponding to the third straight face working face.

Furthermore, chamfers are arranged on the lower part and the upper part of the corresponding surface of the upper centering guide plate and the lower centering guide plate respectively; the chamfering directions of the upper centering guide plate and the lower centering guide plate are the same, and the angles of the upper centering guide plate and the lower centering guide plate are equal; chamfers are arranged on the lower part and the upper part of the corresponding surface of the upper clamping key and the lower clamping key respectively; the chamfering directions of the upper clamping key and the lower clamping key are the same, and the angles of the upper clamping key and the lower clamping key are equal.

The auxiliary drawing mechanism comprises an upper inclined wedge guide plate arranged on the inner side surface of the lower movable pressure plate and a lower inclined wedge guide plate arranged on the outer side surface of the male die and matched with the upper inclined wedge guide plate; the lower part of the upper wedge guide plate and the upper part of the lower wedge guide plate are provided with a fifth inclined plane working surface and a sixth inclined plane working surface which are matched with each other, and the upper part of the upper wedge guide plate and the lower part of the lower wedge guide plate are provided with a fifth straight plane working surface and a sixth straight plane working surface which are matched with each other; the inclination angles of the fifth inclined plane working surface and the sixth inclined plane working surface are equal; and a movement gap is formed between the upper inclined wedge guide plate and the lower inclined wedge guide plate.

An upper reset nitrogen cylinder which is horizontally arranged is arranged on the upper movable pressure plate; a piston rod of the upper resetting nitrogen cylinder is abutted against the side surface of the female die; a lower reset nitrogen cylinder is horizontally arranged on the lower movable pressure plate; and a piston rod of the lower reset nitrogen cylinder is abutted against the side surface of the material pressing ring.

The utility model has the advantages that: 1. the centering mechanism is arranged on the upper movable pressure plate and the lower movable pressure plate, so that the upper movable pressure plate and the lower movable pressure plate can be restored to correct positions even if the reset mechanism of the die is damaged, and the problem of die damage caused by incorrect resetting of the movable pressure plate is avoided;

2. the utility model discloses what be used for resetting upper movable pressure flitch is last centering mechanism, it is a pair of wedge centering baffle that agrees with each other to go up centering mechanism, inclined plane working face and the straight face working face that agrees with each other through last centering baffle and lower centering baffle can be in the course of pushing down, the automatic drive upper movable pressure flitch resets, its simple structure, convenient operation, need not to add any power equipment, the effectual drawing muscle that has guaranteed to set up on lower movable pressure flitch and upper movable pressure flitch aligns each other, offset the upset moment of torsion when the work stress area bears great eccentricity in the pre-extension process, offset the great yawing force between lower movable pressure flitch and upper movable pressure flitch promptly, guaranteed good pre-extension effect;

3. the utility model discloses what be used for the lower movable pressure flitch that resets is lower centering mechanism, and lower centering mechanism is a pair of wedge card key structure that agrees with each other, through the inclined plane working face on the card key structure agrees with each other, can ensure even if under the condition that the reset mechanism damaged originally in the process of pushing down, the pressure flitch also can intact reset, and its structure is very simple, need not to add any power equipment;

4. the utility model is provided with the chamfer structures on the centering guide plate and the clamping key, the chamfer structures can increase the fit degree of the working face and reduce the interference friction;

5. the utility model has the advantages that the upper wedge guide plate and the lower wedge guide plate are mutually matched, the wedge auxiliary drawing mechanism drives the lower movable pressure plate to move during drawing and forming, the structure is simple, and the operation is convenient;

6. the utility model discloses a nitrogen cylinder resets is set up, resets through initiative driven mode drive activity pressure flitch, simple structure, convenient operation.

The utility model can effectively offset the lateral force when the work stress area bears large working force by arranging the centering mechanism, thereby ensuring the pre-extension effect; and under the unable circumstances that resets of movable pressure flitch, can avoid the damage risk that the mould continues to close and lead to through centering mechanism, whole structure is very simple, and it is very convenient to operate, has spreading value.

Drawings

FIG. 1: the drawing die of the utility model is schematically shown in structure;

FIG. 2: the structure schematic diagram of the centering mechanism of the utility model;

FIG. 3: the utility model discloses a schematic diagram of advanced engagement of a centering mechanism;

FIG. 4: the structure of the upper movable material pressing plate is schematic when not resetting;

FIG. 5: the state diagram of the upper centering mechanism when the upper movable pressure plate is not reset is shown;

FIG. 6: the structure schematic diagram of the lower movable pressure plate of the utility model is not reset;

FIG. 7: the state diagram of the lower centering mechanism when the lower movable material pressing plate is not reset is shown;

wherein: 1, a female die; 2, male die; 3, lower centering guide plate; 31 — a second inclined working surface; 32-a second straight face working face; 4, an upper centering guide plate; 41-first inclined working surface; 42 — a first straight work surface; 5, moving a material pressing plate; 51-a boss; 6, moving the material pressing plate; 61-a recess; 71-an upper wedge guide plate; 72-lower wedge guide plate; 73-fifth inclined working face; 74-sixth ramp face; 75-a fifth straight face working face; 76-sixth straight face working face; 8-go up card key; 81-third inclined working face; 82-a third straight face working face; 9-lower catch key; 91-fourth inclined working face; 92-a fourth straight face working face; 10-material pressing ring.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and specific embodiments.

As shown in fig. 1 to 7, the pre-extension drawing die with the functions of loss prevention and lateral force prevention comprises a female die 1, a male die 2 matched with the female die 1, and a material pressing ring 10 for pressing a sheet material, wherein a lower movable material pressing plate 6 is arranged on the material pressing ring 10, an upper movable material pressing plate 5 is arranged on the female die 1, and an auxiliary drawing mechanism is arranged between the lower movable material pressing plate 6 and the male die 2.

As shown in fig. 1 and 4, the auxiliary drawing mechanism of the present embodiment includes an upper wedge guide 71 disposed on the inner side of the lower movable pressure plate 6 and a lower wedge guide 72 disposed on the outer side of the punch 2 and engaged with the upper wedge guide 71, opposite surfaces of the lower wedge guide 72 and the upper wedge guide 71 are engaged with each other to drive the lower movable pressure plate 6 to move along a guide plate on the pressure ring 10, a lower portion of the upper wedge guide 71 and an upper portion of the lower wedge guide 72 are provided with a fifth straight surface working surface 73 and a sixth straight surface working surface 74 engaged with each other, an upper portion of the upper wedge guide 71 and a lower portion of the lower wedge guide 72 are provided with a fifth straight surface working surface 75 and a sixth straight surface working surface 76 engaged with each other, an inclination angle of the fifth straight surface 73 and the sixth straight surface 74 is equal, and the inclined surfaces of the lower wedge guide 72 and the upper wedge guide 71 are engaged with each other during the downward movement of the pressure ring 10, the lower movable pressing plate 6 is driven to slide for a certain stroke along the guide plate in the pressing ring 10, and initially, a movement gap is formed between the upper wedge guide plate 71 and the lower wedge guide plate 72 in the punching direction, so that the purpose is to ensure that the lower movable pressing plate 6 does not move in the process of pre-starting and pre-accelerating the air cushion of the press. The upper wedge guide plate 71 is fixedly connected to the inner side face of the lower movable pressing plate 6 through bolts, the lower wedge guide plate 72 is fixed to the outer side face (main rib side wall) of the male die 2 through bolts, and the size of the movement gap can be adjusted by adjusting the relative distance between the upper wedge guide plate 71 and the lower wedge guide plate 72 in the stamping direction.

An upper reset nitrogen cylinder (not shown in the figure) which is horizontally arranged is arranged on the upper movable pressure plate 5, a piston rod of the upper reset nitrogen cylinder is abutted against the side surface of the female die 1, a lower reset nitrogen cylinder (not shown in the figure) which is horizontally arranged is arranged on the lower movable pressure plate 6, and a piston rod of the lower reset nitrogen cylinder is abutted against the side surface of the pressure ring 10. After the die 1 is closed, the upper movable pressure plate 5 is driven to reset by the upper reset nitrogen cylinder, and the lower movable pressure plate 6 is driven to reset by the lower reset nitrogen cylinder.

In order to avoid the situation that the upper movable pressure plate 5 and the lower movable pressure plate 6 cannot reset when the resetting nitrogen cylinder fails, in the embodiment, a centering mechanism is arranged between the upper movable pressure plate 5 and the lower movable pressure plate 6, as shown in fig. 1 to 7, a protrusion 51 protruding downwards along the vertical direction is arranged on the upper movable pressure plate 5, a recess 61 for accommodating the protrusion 51 is arranged on the lower movable pressure plate 6, the centering mechanism comprises an upper centering mechanism for driving the upper movable pressure plate 5 to reset, as shown in fig. 1 to 7, the upper centering mechanism comprises an upper centering guide plate 4 arranged on one side of the lower end of the protrusion 51 and a lower centering guide plate 3 arranged on one side of the upper end of the recess 61 and corresponding to the upper centering guide plate 4, a first inclined working surface 41 inclining downwards along the vertical direction is arranged on the lower end of one side of the upper centering guide plate 4 facing the lower centering guide plate 3, and a vertical first straight working surface, the upper end of one side of the lower centering guide plate 3 facing the upper centering guide plate 4 is a second inclined working surface 31 which is vertically inclined upwards and has the same inclination angle with the first inclined working surface 41, and the lower end is a second straight working surface 32 corresponding to the first straight working surface 42.

Centering mechanism still includes the lower centering mechanism that is used for driving down activity pressure flitch 6 and resets, centering mechanism is including setting up in last ka ke 8 of bellying 51 lower extreme opposite side and setting up in the lower ka ke 9 that the concave part 61 upper end opposite side corresponds last ka ke 8 down, it is equipped with along vertical downward sloping third inclined plane working face 81 to go up ka ke 8 downward card key 9 one side lower extreme, the upper end is equipped with vertical third straight face working face 82, lower ka ke 9 is upwards for following vertical tilt up's fourth inclined plane working face 91 that equals with third inclined plane working face 81 inclination, the lower extreme is the fourth straight face working face 92 that corresponds third straight face working face 82 towards upper end of ka ke 8 one side.

In addition, chamfers are arranged on the lower portion and the upper portion of the surface, corresponding to the lower centering guide plate 3, of the upper centering guide plate 4, chamfers are arranged on the lower portion and the upper portion of the surface, corresponding to the lower clamping key 9, of the upper clamping key 8, chamfers are arranged on the lower portion and the upper portion of the surface, corresponding to the lower clamping key 9, of the upper centering guide plate 4, and chamfers are arranged on the lower centering guide plate 4 and the lower centering guide plate 3. The chamfer structure can avoid producing the interference, reduces mutual frictional resistance.

In actual operation, as shown in fig. 3, the engagement amount of the third straight face 82 of the upper catch 8 with the fourth straight face 92 of the lower catch 9 is at least 20mm (as D2 in fig. 3), and the engagement amount of the second straight face 32 of the lower centering and guide plate 3 and the first straight face 42 of the upper centering and guide plate 4 is at least 20mm (as D3 in fig. 3) before the work stress area contacts 20mm (as D1 in fig. 3), i.e. before the nip of the work stress area and the draw bead contact; then the female die 1 descends, the working stress area begins to contact, the draw bead is formed, and the material clamping and pre-extending actions are started. In the process, the upper centering guide plate 4 and the lower centering guide plate 3 can effectively ensure that the draw beads arranged on the lower movable pressure plate 5 and the upper movable pressure plate 6 are aligned with each other; and the overturning torque when the working stress area bears larger eccentricity in the pre-extension process is offset, namely, the larger lateral force between the lower movable pressure plate 6 and the upper movable pressure plate 5 is offset, and the good pre-extension effect is ensured.

Under the extreme working condition, the upper movable pressure plate 5 is in a risk of being stuck and not resetting. For example, in the case that the upper reset nitrogen cylinder of the upper movable pressure plate 5 fails, as shown in fig. 4 to 5, the upper movable pressure plate 5 cannot be pushed to the initial position by the upper reset nitrogen cylinder, and considering that the upper movable pressure plate 5 is at the limit of the stroke point at the outermost side of the figure, at this time, the female die 1 moves downward to the figure, and the upper centering guide plate 4 and the lower centering guide plate 3 contact in advance before the working stress area does not contact.

Namely, the first inclined working surface 41 of the upper centering guide plate 4 is meshed with the second inclined working surface 31 of the lower centering guide plate 3, and the meshing amount is at least 30 mm; thereafter, when the female die 1 continues to descend, due to the action of the first inclined working surface 41 and the second inclined working surface 31, the upper movable pressure plate is forced to be pushed for a certain stroke until the contact between the first inclined working surface 41 and the second inclined working surface 31 is finished, and the state is changed to the state shown in fig. 3, namely, the first straight working surface 42 of the upper centering guide plate 4 is contacted with the second straight working surface 32 of the lower centering guide plate 3, the third straight working surface 82 of the upper clamp key 8 is contacted with the fourth straight working surface 92 of the lower clamp key 9, and then the female die 1 continues to descend, so that the working stress area can be normally contacted, and the situation that the upper movable pressure plate 5 and the lower movable pressure plate 6 are dislocated cannot occur; in the action process, the non-reset state of the upper movable pressure plate 5 is considered according to the limit position. Namely, the upper movable material pressing plate is clamped at any position within the limit position, and the upper centering guide plate 4 and the lower centering guide plate 3 can prevent the occurrence of die damage accidents.

Under extreme working conditions, the lower movable pressure plate 6 is considered to have the risk of being stuck and not reset. For example, when the lower reset nitrogen cylinder of the lower movable pressure plate 6 fails, as shown in fig. 6 to 7, the lower movable pressure plate 6 cannot be pushed to the initial position by the lower reset nitrogen cylinder, and the limit state of the stroke point of the movable pressure plate 6 at the outermost side in the figure is considered. At the moment, the female die 1 descends to the state shown in the figure, and the upper clamping key 8 and the lower clamping key 9 are contacted in advance before the working stress area is not contacted.

That is, the third inclined surface 81 of the upper latch 8 and the fourth inclined surface 91 of the lower latch 9 are engaged with each other by at least 30 mm. Thereafter, when the female die 1 continues to descend, due to the action of the third inclined working surface 81 and the fourth inclined working surface 91, the lower movable pressure plate 6 can be forcibly pushed for a certain stroke until the contact between the third inclined working surface 81 and the fourth inclined working surface 91 is finished, and the state is changed to the state shown in fig. 3, namely, the second straight working surface 32 of the lower centering guide plate 3 contacts with the first straight working surface 42 of the upper centering guide plate 4, the third straight working surface 82 of the upper clamp key 8 contacts with the fourth straight working surface 92 of the lower clamp key 9, and then the female die 1 continues to descend, so that the working stress area can be in normal contact, and the situation that the upper movable pressure plate 5 and the lower movable pressure plate 6 are dislocated cannot occur; in the above operation, the state in which the lower movable pressure plate 6 is not reset is considered as the limit position. Namely, the lower movable pressure plate 6 is clamped at any position within the limit position, and the upper clamping key 8 and the lower clamping key 9 can prevent the occurrence of die damage accidents.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that the foregoing embodiments and descriptions are provided only to illustrate the principles of the present invention without departing from the spirit and scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (6)

1. A pre-extension drawing die with the functions of preventing damage and lateral force comprises a female die (1), a male die (2) matched with the female die (1) and a material pressing ring (10) used for pressing a sheet material; a lower movable pressing plate (6) is arranged on the pressing ring (10), and an upper movable pressing plate (5) is arranged on the female die (1); an auxiliary drawing mechanism is arranged between the male die (2) and the lower movable pressing plate (6),

the method is characterized in that: the upper movable pressure plate (5) is provided with a bulge part (51) which is vertically and downwards bulged; a concave part (61) for accommodating the convex part (51) is arranged on the lower movable pressure plate (6); and a centering mechanism for driving the upper movable pressure plate (5) and the lower movable pressure plate (6) to reset in the pressing process is arranged between the convex part (51) and the concave part (61).

2. A pre-draw die having damage and side force prevention as claimed in claim 1, wherein: the centering mechanism comprises an upper centering mechanism for driving the upper movable pressure plate (5) to reset; the upper centering mechanism comprises an upper centering guide plate (4) arranged on one side of the lower end of the protruding part (51) and a lower centering guide plate (3) arranged on one side of the upper end of the recessed part (61) and corresponding to the upper centering guide plate (4); the lower end of one side, facing the lower centering guide plate (3), of the upper centering guide plate (4) is provided with a first inclined working surface (41) which is vertically inclined downwards, and the upper end of the side is provided with a vertical first straight working surface (42); the upper end of one side of the lower centering guide plate (3), which faces the upper centering guide plate (4), is a second inclined working surface (31) which is inclined upwards along the vertical direction and has the same inclination angle with the first inclined working surface (41), and the lower end is a second straight working surface (32) which corresponds to the first straight working surface (42).

3. A pre-draw die with damage and side force prevention as set forth in claim 2, wherein: the centering mechanism comprises a lower centering mechanism for driving the lower movable pressing plate (6) to reset; the lower centering mechanism comprises an upper clamping key (8) arranged on the other side of the lower end of the protruding part (51) and a lower clamping key (9) arranged on the other side of the upper end of the recessed part (61) and corresponding to the upper clamping key (8); the lower end of one side, facing the lower clamping key (9), of the upper clamping key (8) is provided with a third inclined working surface (81) which is vertically inclined downwards, and the upper end of the upper clamping key is provided with a vertical third straight working surface (82); lower calorie of key (9) upwards card key (8) one side upper end be along vertical tilt up with fourth inclined plane working face (91) that third inclined plane working face (81) inclination equals, lower extreme be fourth straight face working face (92) that correspond third straight face working face (82).

4. A pre-draw die with damage and side force prevention as set forth in claim 3 wherein: chamfers are arranged on the lower part and the upper part of the surface, corresponding to the lower centering guide plate (3), of the upper centering guide plate (4); the chamfering directions of the upper centering guide plate (4) and the lower centering guide plate (3) are the same, and the angles are equal; chamfers are arranged on the lower part and the upper part of the upper clamping key (8) corresponding to the lower clamping key (9); the chamfering directions of the upper clamping key (8) and the lower clamping key (9) are the same, and the angles are equal.

5. The pre-stretching drawing die with the functions of preventing damage and preventing lateral force as set forth in any one of claims 1 to 4, wherein: the auxiliary drawing mechanism comprises an upper inclined wedge guide plate (71) arranged on the inner side surface of the lower movable pressure plate (6) and a lower inclined wedge guide plate (72) arranged on the outer side surface of the male die (2) and matched with the upper inclined wedge guide plate (71); a fifth inclined plane working surface (73) and a sixth inclined plane working surface (74) which are matched with each other are arranged at the lower part of the upper inclined wedge guide plate (71) and the upper part of the lower inclined wedge guide plate (72), and a fifth straight plane working surface (75) and a sixth straight plane working surface (76) which are matched with each other are arranged at the upper part of the upper inclined wedge guide plate (71) and the lower part of the lower inclined wedge guide plate (72); the inclination angles of the fifth inclined working surface (73) and the sixth inclined working surface (74) are equal; and a movement gap is formed between the upper inclined wedge guide plate (71) and the lower inclined wedge guide plate (72).

6. A pre-draw die having damage and side force prevention as claimed in claim 1, wherein: an upper reset nitrogen cylinder which is horizontally arranged is arranged on the upper movable pressure plate (5); a piston rod of the upper resetting nitrogen cylinder is abutted against the side surface of the female die (1); a lower reset nitrogen cylinder which is horizontally arranged is arranged on the lower movable pressure plate (6); and a piston rod of the lower reset nitrogen cylinder is abutted against the side surface of the material pressing ring (10).

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