CN220347791U - Spring piece type fall-preventing mechanism - Google Patents

Abstract

The utility model discloses a spring piece type anti-falling mechanism, which comprises a base, a chuck used for guiding and clamping a workpiece, and a spring piece used for providing elasticity for the chuck, wherein a first end of the spring piece is connected with the base, a second end of the spring piece is connected with the chuck, the chuck is provided with a working curved surface, the working curved surface is divided into a demarcation area, a feeding area and a clamping area which are distributed on two sides of the demarcation area, the feeding area comprises a maximum feeding area and an optimal feeding area which are adjacent, the workpiece is led in from the maximum feeding area, the chuck contacts the workpiece to start to bear force when the workpiece reaches the optimal feeding area, the workpiece continues to be led in the spring piece to bear force outwards to the maximum, a positioning surface of the workpiece is tightly attached to a supporting surface of a machining clamp after the workpiece is completely led in, and the spring piece slightly bends outwards to provide a acting force for the workpiece to clamp the workpiece; the workpiece fixing device has the advantages that the workpiece can be stably fixed without additional operation, the positioning surface of the workpiece and the supporting surface of the machining clamp can be always kept in fit, and smooth and convenient feeding and discharging of the workpiece can be ensured.

Description

Spring piece type fall-preventing mechanism

Technical Field

The utility model relates to a structure for preventing a workpiece from tilting or falling off for horizontal four-axis machining center equipment, in particular to a spring piece type tilting prevention mechanism.

Background

The existing horizontal four-axis (B-axis) machining center equipment is used for better machining of workpieces, machining fixtures are usually vertical plates, the workpieces are hung on the vertical plates of the machining fixtures, the positioning mode is one-side two pins, specific positioning mechanisms for different workpieces are different, and the first positioning mechanism is that: the positioning on the workpiece adopts three blank positioning surfaces, a blank conical hole (serving as a positioning hole) and a blank waist-shaped hole (serving as a positioning hole), and the positioning on the machining fixture adopts three small supports (serving as supporting surfaces) and two spring conical pins (serving as positioning pins); the second positioning mechanism is as follows: the positioning on the workpiece adopts a finish machining large surface (serving as a positioning surface) and two finish machining holes (serving as positioning holes), and the positioning on the machining fixture adopts a large surface support (serving as a supporting surface), an expansion pin (serving as a positioning pin) and a diamond pin (serving as a positioning pin).

The clamping process of the workpiece is as follows: the worker places the workpiece on the machining fixture, the positioning hole of the workpiece is aligned with the positioning pin of the machining fixture, and the positioning surface of the workpiece is attached to the supporting surface of the machining fixture; then, starting the horizontal four-axis (B-axis) machining center equipment, automatically closing the equipment door, and sequentially clamping the oil cylinders on the machining clamp to finish positioning and clamping the workpiece. However, there is a great problem in that the work is unstable when it is hung on the vertical plate of the machining jig, and the work is easily inclined or dropped after the worker releases his hand, specifically: aiming at the first positioning mechanism, the spring taper pin can eject the workpiece outwards, and the pneumatic pressure on the supporting surface can eject the workpiece outwards, so that the workpiece is easy to incline or drop; aiming at the second positioning mechanism, the positioning mechanism is usually used for a finishing process, the air detection pressure on a supporting surface is larger during the finishing process, the expansion pin and the diamond pin are in clearance with a finishing hole, particularly the clearance at the expansion pin is large, and the workpiece is easy to incline or drop due to the posture and the gravity center of the workpiece; in addition, various vibrations can be generated in the running process of the horizontal four-axis (B-axis) machining center equipment, and the workpiece can be pushed laterally in the positioning and clamping processes, so that the stability of the workpiece is difficult to ensure. Once the workpiece is inclined and separated from the supporting surface, the machining clamp is easy to be positioned and clamped in place, so that the workpiece is unqualified to be machined or a collision accident occurs; the workpiece is easy to damage or cause industrial accidents when the workpiece falls.

In order to prevent the workpiece from tilting or falling, the traditional method is that after a worker hangs the workpiece, the pressing plate is locked by the screw nut, so that the workpiece can be well preliminarily fixed on the machining clamp, but additional operation such as screw locking is needed for fixing the workpiece, time and labor are wasted, and the production efficiency is seriously influenced. The general method is that the quick clamp is used, so that a workpiece can be clamped and fixed well and quickly, but the external dimension of the quick clamp is large, the workpiece processing can be influenced, or the quick clamp is unfavorable for small space use, such as the use in a machining clamp with a compact structure, and cannot be used; and when the work piece is great, just need a plurality of quick clamps, use quick clamp to be extra operation, waste time and energy, a plurality of quick clamps can influence production efficiency greatly, and quick clamp is operated by the manual work in addition, is very likely to appear the maloperation. The two modes are not ideal because misoperation or missing operation of workers can occur.

Then, a spring buckle structure is introduced, and the structure is pushed forward mainly by a spring and clamps a workpiece by using a ball head or a roller. When the structure is used, the direction is vertical spring force when the workpiece is placed, so that the workpiece is blocked when the workpiece is placed beyond the radius of the ball head, the workpiece is not placed in the structure, the workpiece is difficult to load and unload, and the worker is easy to violently load and unload, so that the structure is often damaged or the ball head and the spring of the structure are loose or lost, the maintenance is very difficult, the workpiece is difficult to place when the ball head is smaller, the integral structure is also increased when the ball head is enlarged, and the clamping of small workpieces is very unfavorable. The clamping point position of the structure is important, but the position of the structure can be adjusted only front and back, can not be adjusted up and down, is easy to clamp when the workpiece error is large, can not adapt to the condition of large workpiece error, and is not ideal.

The ideal structure for preventing the workpiece from tilting or falling can automatically fix the workpiece after the workpiece is placed at the positioning position of the machining clamp without additional operation, no matter the vibration in the running process of equipment or the lateral pushing in the positioning and clamping process, the positioning surface of the workpiece and the supporting surface of the machining clamp are always attached, the workpiece is very smooth and convenient to mount and dismount, and meanwhile, the structure is very small and exquisite and durable, is not easy to damage and is convenient to adjust and maintain. Therefore, it is necessary to study a structure for preventing the workpiece from tilting or falling more toward an ideal one.

Disclosure of Invention

The utility model aims to solve the technical problem of providing the elastic piece type anti-falling mechanism, which can stably fix a workpiece without additional operation, can ensure that the positioning surface of the workpiece and the supporting surface of the machining clamp are always attached, can ensure that the feeding and discharging of the workpiece are smooth and convenient, and is simple and small.

The technical scheme adopted for solving the technical problems is as follows: the utility model provides a shell fragment formula fall prevention mechanism, its characterized in that includes the base that is used for fixing fall prevention mechanism, be used for the guide with press from both sides the chuck of tight work piece, be used for giving the chuck provide the shell fragment of elasticity, the first end of shell fragment with pedestal connection, the second end of shell fragment with the chuck be connected, the chuck have a working curved surface, the working curved surface divide into the demarcation district and distribute in the material loading district and the chucking district of demarcation district both sides, the material loading district include the biggest material loading district and the optimum material loading district that adjoin, the work piece is followed the biggest material loading district is imported, the work piece reaches the optimum material loading district the chuck begin the atress of contacting the work piece, the work piece is continued to be imported the shell fragment atress outwards crooked to the biggest, the locating surface of work piece and the holding surface of machine adds anchor clamps closely laminating after the work piece is fully imported, outwards crooked give the work piece a effort, receive the chucking power of two directions for the work piece.

The maximum feeding area, the optimal feeding area and the clamping area are conical surfaces, and the workpiece is fed from the wide end to the narrow end of the maximum feeding area, from the wide end to the narrow end of the optimal feeding area and from the narrow end of the clamping area to the clamping area. In the structure, the maximum feeding area and the optimal feeding area are designed into conical surfaces, so that the workpiece can be fed and discharged more smoothly, the conical surfaces are in point contact with the clamping heads, the feeding and discharging resistance is reduced, and the defect that the feeding and discharging of the existing mechanism are difficult is overcome; the clamping area is designed into a conical surface, and the conical surface enables the workpiece to be in point contact with the chuck, so that clamping is more stable.

The included angle between the maximum feeding area and the demarcation area is 40 degrees, and the included angle between the optimal feeding area and the demarcation area is 15 degrees. In this structure, the angle of the maximum feeding area and the optimal feeding area is designed to increase the feeding area, so that the workpiece with larger error can be guided to the position smoothly.

The included angle between the clamping area and the demarcation area is 40 degrees. In this structure, the angle design in chucking district makes the work piece atress towards the holding surface of machine adds anchor clamps, also makes to get the material easier simultaneously, is difficult to the fastener.

The anti-falling mechanism further comprises a first stabilizing piece for reinforcing the fixing force between the first end of the elastic piece and the base, the first stabilizing piece is arranged on the first end of the elastic piece, the first end of the elastic piece is clamped between the first stabilizing piece and the base, and a first fastener penetrates through the first stabilizing piece and the first end of the elastic piece to be locked with the base. In the structure, the fixing force between the elastic sheet and the base is enhanced by the arrangement of the first stabilizing sheet; the first fastener is a screw, is convenient to install and maintain and is not easy to damage or loosen.

The anti-falling mechanism further comprises a second stabilizing piece for reinforcing the fixing force between the second end of the elastic piece and the clamping head and protecting the elastic piece, the second stabilizing piece is arranged on the second end of the elastic piece, the second end of the elastic piece is clamped between the second stabilizing piece and the clamping head, and a second fastener penetrates through the second stabilizing piece and the second end of the elastic piece to be locked with the clamping head. In the structure, the second stabilizing piece is arranged to strengthen the fixing force between the elastic piece and the chuck; the second fastener is a screw, is convenient to install and maintain and is not easy to damage or loosen.

The second end of the elastic sheet is provided with a front-rear position adjusting mechanism for adjusting the front-rear position of the chuck.

The front-rear position adjusting mechanism comprises a strip-shaped adjusting hole and a second fastening piece, wherein the strip-shaped adjusting hole is formed in the second end of the elastic piece, and the second fastening piece penetrates through the second stabilizing piece and the strip-shaped adjusting hole to be locked with the clamping head. In the structure, the front and back positions of the clamping head can be conveniently adjusted through the strip-shaped adjusting hole on the second end of the elastic sheet and by utilizing the second fastening piece, the structure can be well adapted to the situation that the manufacturing errors of the machining clamp and the workpiece are large, and the defect that the conventional mechanism such as a spring buckle structure is inconvenient to adjust is overcome.

The base is provided with an up-down position adjusting mechanism for adjusting the up-down position of the chuck.

The upper and lower position adjusting mechanism comprises a U-shaped adjusting groove and a third fastening piece which are arranged on the base, and the third fastening piece penetrates through the U-shaped adjusting groove to be tightly locked with the vertical plate of the machining clamp. In the structure, the upper and lower positions of the anti-falling mechanism can be conveniently adjusted by the U-shaped adjusting groove on the base and the third fastener, so that the structure can be well adapted to the situation that the manufacturing errors of the machining clamp and the workpiece are large, and the defect that the conventional mechanism such as a spring buckle structure is inconvenient to adjust is overcome; the third fastener is a screw, is convenient to install and maintain and is not easy to damage or loosen.

Compared with the prior art, the utility model has the advantages that:

1) The workman directly puts the work piece on the holding surface of machine adds anchor clamps, realizes automatic fixed work piece through the elasticity that the shell fragment provided, need not extra operation and just can make the locating surface of work piece closely laminate all the time with the holding surface of machine adds anchor clamps, has solved the shortcoming that current mechanism needs extra operation, has reduced intensity of labour, has prevented maloperation or has leaked the operation, has saved process time to the work piece can not cause work piece slope or drop because of dead weight, the condition such as rotation machine adds anchor clamps or rocks the work piece after the workman loosens the hand.

2) The work curved surface of the chuck is divided into a demarcation area and a feeding area and a clamping area which are distributed on two sides of the demarcation area, the feeding area comprises a maximum feeding area and an optimal feeding area which are adjacent, a workpiece is led in from the maximum feeding area, the chuck contacts the workpiece to start to be stressed when the workpiece reaches the optimal feeding area, the workpiece continues to be outwards bent to the maximum by leading in an elastic sheet stress, the positioning surface of the workpiece is tightly attached to the supporting surface of the machining clamp after the workpiece is completely led in, the elastic sheet is outwards slightly bent to provide an acting force for the workpiece to clamp the workpiece, the special structure of the chuck can realize that the workpiece is fed in and discharged more smoothly and conveniently, and the workpiece in the clamping area obtains clamping force in two directions, so that the clamping effect is better.

3) The elastic sheet is used, so that a workpiece can obtain reliable clamping force, and a doubled feeding area can be obtained in a non-vertical feeding state, and a worker can place the workpiece more easily.

4) The fall-preventing mechanism is of a slender structure, is simple and small in structure, has small volume in the working direction, overcomes the defect of large volume of the existing mechanism, and is suitable for the condition of limited space.

5) When the fall-preventing mechanism is used, the elastic sheet is reversely bent due to elasticity, violent loading and unloading do not exist, and the fall-preventing mechanism cannot be damaged.

6) Through changing chuck style and shell fragment size etc. this fall prevention mechanism can realize the use of different directions and different power, if can vertical installation, flat installation, inclined installation or fall installation, adapts to the great condition of work piece error.

7) The elastic force of the elastic sheet can be fixed or adjustable, so that the elastic sheet can be well adapted to workpieces with different sizes.

Drawings

FIG. 1 is a schematic structural view of a spring type fall prevention mechanism according to the present utility model;

FIG. 2 is a front view of the spring type fall prevention mechanism of the present utility model;

FIG. 3 is a schematic view of a partially exploded structure of the spring anti-fall mechanism of the present utility model;

FIG. 4 is a schematic structural view of a chuck in the spring anti-fall mechanism according to the present utility model;

FIG. 5 is a front view of the chuck in the spring fall prevention mechanism of the present utility model;

FIG. 6 is a top view of FIG. 5;

FIG. 7 is a schematic diagram of an embodiment of a spring fall prevention mechanism according to the present utility model;

FIG. 8 is a second schematic application diagram of the spring anti-falling mechanism of the present utility model;

FIG. 9a is a schematic picture of the locating surface of the workpiece and the support surface of the machining fixture before the workpiece is unsecured;

FIG. 9b is a schematic illustration of the locating surface of the workpiece and the support surface of the machined fixture after securing the workpiece using the spring anti-roll mechanism of the present utility model;

FIG. 10 is a schematic diagram showing the state change process of the spring anti-fall mechanism of the present utility model when in use;

FIG. 11 is a force exploded schematic view of the collet in the spring fall prevention mechanism of the present utility model;

fig. 12 is a schematic view of an application of the spring-type fall prevention mechanism after the chuck style and the spring-type dimensions are changed.

Detailed Description

The utility model is described in further detail below with reference to the embodiments of the drawings.

The utility model provides a spring piece type anti-falling mechanism, as shown in fig. 1 to 6, which comprises a base 1 for fixing the anti-falling mechanism, a chuck 2 for guiding and clamping a workpiece, and a spring piece 3 for providing elasticity for the chuck 2, wherein the first end of the spring piece 3 is connected with the base 1, the second end of the spring piece 3 is connected with the chuck 2, the chuck 2 is provided with a working curved surface 21, the working curved surface 21 is divided into a boundary region 211, and a feeding region and a clamping region 214 distributed on two sides of the boundary region 211, the feeding region comprises a maximum feeding region 212 and an optimal feeding region 213 which are adjacent, when the workpiece is led in from the maximum feeding region 212, the chuck 2 is stressed when the workpiece reaches the optimal feeding region 213, the workpiece is continuously led in the spring piece 3 to be stressed outwards to be the maximum, the positioning surface of the workpiece is tightly attached to the supporting surface of the machining clamp, the spring piece 3 is slightly bent outwards to provide a acting force for the workpiece, and the workpiece is subjected to clamping force in two directions in the clamping region 214. When the automatic clamping device is used, a worker directly places a workpiece on the supporting surface of the machining clamp, the workpiece is automatically fixed through the elastic force provided by the elastic sheet 3, the positioning surface of the workpiece and the supporting surface of the machining clamp can be always and tightly attached without additional operation, the defect that the existing mechanism needs additional operation is overcome, the labor intensity is reduced, misoperation or missing operation is prevented, the processing time is saved, and the workpiece is not inclined or dropped due to the conditions of dead weight, rotation of the machining clamp or shaking of the workpiece after the worker loosens hands; the special structure of the chuck 2 can realize smoother and more convenient feeding and discharging of the workpiece, and the workpiece obtains clamping forces in two directions in the clamping area 214, so that the clamping effect is better; the elastic sheet 3 is used, so that a workpiece can obtain reliable clamping force, and a doubled feeding area can be obtained in a non-vertical feeding state, and a worker can place the workpiece more easily; the fall-preventing mechanism is of a slender structure, is simple and small in structure, has small volume in the working direction, overcomes the defect of larger volume of the existing mechanism, and is suitable for the condition of limited space; when the fall-preventing mechanism is used, the elastic sheet 3 is reversely bent due to elasticity, violent loading and unloading do not exist, and the fall-preventing mechanism cannot be damaged.

In a specific embodiment, the maximum loading area 212, the optimal loading area 213 and the clamping area 214 are conical surfaces, and the workpiece is loaded from the wide end to the narrow end of the maximum loading area 212, from the wide end to the narrow end of the optimal loading area 213, and from the narrow end of the clamping area 214 to the clamping area 214. In the structure, the maximum feeding area 212 and the optimal feeding area 213 are designed into conical surfaces, so that the workpiece feeding and discharging are smoother, the conical surfaces are in point contact with the clamping heads 2, the feeding and discharging resistance is reduced, and the defect of difficult feeding and discharging of the existing mechanism is overcome; by designing the clamping area 214 as a conical surface, the conical surface makes point contact with the workpiece and the chuck 2, so that the clamping is more stable.

In a specific embodiment, the included angle between the maximum feeding area 212 and the boundary area 211 is 40 degrees, the included angle between the optimal feeding area 213 and the boundary area 211 is 15 degrees, and the angles of the maximum feeding area 212 and the optimal feeding area 213 are designed to increase the feeding area, so that the workpiece with larger error can be guided smoothly; the included angle between the clamping area 214 and the demarcation area 211 is 40 degrees, and the angle design of the clamping area 214 enables the workpiece to be stressed towards the supporting surface of the machining clamp, so that the material taking is easier, and the clamping piece is not easy.

In another specific embodiment, the fall-preventing mechanism further includes a first fixing piece 41 for reinforcing a fixing force between the first end of the elastic piece 3 and the base 1, the first fixing piece 41 is disposed on the first end of the elastic piece 3, and the first end of the elastic piece 3 is clamped between the first fixing piece 41 and the base 1, the first fastener 51 passes through the first fixing piece 41 and the first end of the elastic piece 3 to be locked with the base 1, and the fixing force between the elastic piece 3 and the base 1 is reinforced by the arrangement of the first fixing piece 41; the first fastener 51 is a screw, is convenient to install and maintain, and is not easy to damage or loosen; the fall-preventing mechanism further comprises a second stabilizing piece 42 for reinforcing the fixing force between the second end of the spring piece 3 and the chuck 2 and protecting the spring piece 3, the second stabilizing piece 42 is arranged on the second end of the spring piece 3, the second end of the spring piece 3 is clamped between the second stabilizing piece 42 and the chuck 2, the second fastener 52 penetrates through the second stabilizing piece 42 and the second end of the spring piece 3 to be locked with the chuck 2, and the fixing force between the spring piece 3 and the chuck 2 is reinforced by the arrangement of the second stabilizing piece 42; the second fastener 52 is a screw, is easy to install and maintain, and is not easily damaged or loosened.

In other specific embodiments, the second end of the elastic sheet 3 is provided with a front-rear position adjusting mechanism for adjusting the front-rear position of the chuck 2, the front-rear position adjusting mechanism comprises a strip-shaped adjusting hole 31 and a second fastening piece 52 which are arranged on the second end of the elastic sheet 3, the second fastening piece 52 passes through the second stabilizing piece 42 and the strip-shaped adjusting hole 31 to be locked with the chuck 2, the front-rear position of the chuck 2 can be conveniently adjusted by utilizing the second fastening piece 52 through the strip-shaped adjusting hole 31 on the second end of the elastic sheet 3, the situation that the manufacturing errors of a machining clamp and a workpiece are large can be well adapted, and the defect that the conventional mechanism such as a spring buckle structure is inconvenient to adjust is overcome; the base 1 is provided with an up-down position adjusting mechanism for adjusting the up-down position of the chuck 2, the up-down position adjusting mechanism comprises a U-shaped adjusting groove 11 and a third fastening piece 53 which are arranged on the base 1, the third fastening piece 53 passes through the U-shaped adjusting groove 11 to be tightly locked with a vertical plate of the mechanical clamp, the up-down position of the anti-falling mechanism can be conveniently adjusted by the U-shaped adjusting groove 11 on the base 1 and the third fastening piece 53, the situation that the manufacturing errors of the mechanical clamp and a workpiece are large can be well adapted, and the defect that the conventional mechanism such as a spring buckle structure is inconvenient to adjust is overcome; the third fastener 53 is a screw, is easy to install and maintain, and is not easily damaged or loosened.

In each of the above embodiments, as shown in fig. 4, 5 and 6, the chuck 2 is a solid body, the chuck 2 has a mounting surface 22 opposite to the working curved surface 21, the mounting surface 22 is taken as the bottom surface of the chuck 2, two opposite end surfaces 23 at the lower part of the chuck 2 are isosceles trapezoids, the upper parts of the two opposite end surfaces are designed to be arc structures protruding upwards, the arc structures at one end are positioned higher than the arc structures at the other end, the two opposite side surfaces 24 at the lower part of the chuck 2 are inclined surfaces expanding from top to bottom, the working curved surface 21 is an irregular curved surface, one end of the maximum feeding area 212 is integrated with the arc structures at the higher position, one end of the clamping area 214 is integrated with the arc structures at the lower position, and the two inclined surfaces are respectively extended upwards to the curve sides at both sides of the working curved surface 21, so that the whole chuck 2 is isosceles trapezoid when being observed from the side of the maximum feeding area 212, see fig. 6.

Fig. 7 and 8 are schematic views showing the application of the spring-type fall prevention mechanism of the present utility model, wherein 100 represents the spring-type fall prevention mechanism, 200 represents a vertical plate of the machining jig, and 300 represents a workpiece. In fig. 7, 3 spring type fall preventing mechanisms 100 are used for fixing one workpiece 300, and in fig. 8, 6 spring type fall preventing mechanisms 100 are used for fixing two workpieces 300.

Fig. 9a shows a schematic picture of the positioning surface of the workpiece and the supporting surface of the machining fixture before the workpiece is not fixed, and fig. 9b shows a schematic picture of the positioning surface of the workpiece and the supporting surface of the machining fixture after the workpiece is fixed by using the elastic sheet type fall prevention mechanism of the utility model, and as can be seen from fig. 9b, the positioning surface 301 of the workpiece 300 is always closely attached to the supporting surface 201 of the machining fixture.

Fig. 10 shows a schematic picture of the state change process of the spring anti-falling mechanism in application, wherein the first state is a free state, the second state is that the workpiece contacts the chuck to start to be stressed, the third state is that the spring is stressed to be outwards bent to the maximum, the fourth state is that the positioning surface of the workpiece is attached to the supporting surface of the machining clamp, and the spring is outwards slightly bent to provide an acting force for the workpiece. Fig. 11 shows a stress decomposition schematic picture of the chuck in the spring type fall prevention mechanism of the utility model, wherein the loading state is the stress condition of the second state in fig. 10, and the clamping stress is the stress decomposition of the fourth state in fig. 10.

In the above embodiments, the elastic force of the elastic sheet 3 can be fixed or adjustable, so that workpieces with different sizes can be well adapted; the spring plate 3 is made of X10CRNI18-8 (1.4310) German DIN standard stainless steel, which is equivalent to 1Cr17Ni7 in China and SUS301 in Japan; by changing the style of the chuck 2 and the size of the spring plate 3, the anti-falling mechanism can realize the use of different directions and different forces, such as vertical installation, horizontal installation, inclined installation or falling installation, and is suitable for the condition of larger workpiece errors, and fig. 12 shows an application schematic diagram of the spring plate anti-falling mechanism after changing the style of the chuck and the size of the spring plate, and the function of the spring plate anti-falling mechanism 400 after changing is rough guiding compatible clamping.

Claims (10)

1. The utility model provides a shell fragment formula fall prevention mechanism, its characterized in that includes the base that is used for fixing fall prevention mechanism, be used for the guide with press from both sides the chuck of tight work piece, be used for giving the chuck provide the shell fragment of elasticity, the first end of shell fragment with base connection, the second end of shell fragment with the chuck be connected, the chuck have a working curved surface, the working curved surface divide into the demarcation district and distribute in the material loading district and the chucking district of demarcation district both sides, the material loading district include the biggest material loading district and the optimum material loading district that adjoin, the work piece is followed the biggest material loading district is imported, the work piece reaches the optimum material loading district the chuck begin the atress of contacting the work piece, the work piece is continued to be imported the shell fragment atress outwards crooked to the biggest, the locating surface of work piece and the holding surface of machine adds anchor clamps closely laminating after the work piece is fully imported, outwards crooked provide an effort for the work piece and press from both sides the work piece tightly.

2. The elastic sheet type fall prevention mechanism according to claim 1, wherein the maximum feeding area, the optimal feeding area and the clamping area are conical surfaces, and the workpiece is fed from the wide end to the narrow end of the maximum feeding area, from the wide end to the narrow end of the optimal feeding area and from the narrow end of the clamping area to the clamping area.

3. The spring type fall preventing mechanism according to claim 2, wherein an included angle between the maximum feeding area and the demarcation area is 40 degrees, and an included angle between the optimum feeding area and the demarcation area is 15 degrees.

4. A spring type fall prevention mechanism according to claim 3, wherein an included angle between said clamping area and said demarcation area is 40 degrees.

5. The spring fall prevention mechanism according to any one of claims 1 to 4, further comprising a first securing tab for enhancing a securing force between the first end of the spring and the base, the first securing tab being disposed on the first end of the spring, the first end of the spring being sandwiched between the first securing tab and the base, and a first fastener passing through the first securing tab and the first end of the spring to be locked with the base.

6. The spring fall prevention mechanism according to claim 5, further comprising a second securing tab for enhancing a securing force between the second end of the spring and the chuck and protecting the spring, the second securing tab being disposed on the second end of the spring, the second end of the spring being clamped between the second securing tab and the chuck, and a second fastener passing through the second securing tab and the second end of the spring to be locked with the chuck.

7. The spring fall prevention mechanism according to claim 6, wherein the second end of the spring is provided with a front-rear position adjusting mechanism for adjusting the front-rear position of the chuck.

8. The spring fall prevention mechanism according to claim 7, wherein said front-to-rear position adjustment mechanism comprises an elongated adjustment hole formed in said second end of said spring and said second fastener, said second fastener passing through said second stabilizing tab and said elongated adjustment hole to be locked with said chuck.

9. The spring fall prevention mechanism according to claim 1, wherein the base is provided with an up-down position adjusting mechanism for adjusting the up-down position of the chuck.

10. The spring type fall prevention mechanism according to claim 9, wherein the vertical position adjusting mechanism comprises a U-shaped adjusting groove and a third fastening piece which are arranged on the base, and the third fastening piece passes through the U-shaped adjusting groove to be tightly locked with the vertical plate of the machining clamp.