WO1994023876A1 - Method of precisely shearing piping material and apparatus therefor - Google Patents

Abstract

The invention has its object to provide a method of precisely shearing a piping material to provide a high-precision sheared end which has small irregularities and is free of scratches and gossan, and an apparatus therefor. The invention has a feature of performing high speed shearing with a tension applied to a piping material in an axial direction thereof, when the piping material is to be sheared by means of a mandrel. The axial tension amounts to 1.5 % or more and less than 100 % of a yield stress of the material, and a shearing speed is equal to or more about 1 m/sec. An apparatus of the invention comprises a stationary blade (3) secured to a shearing type frame (2) and provided with a hole (30), through which a piping material W is passed to a predetermined position, a floating mandrel (13) inserted into the piping material W, a movable blade (4) which has a hole (40) for permitting the piping material W to pass therethrough and a stationary mandrel (14) concentric with the hole (40), and a holder (4a) for securing thereto the movable blade (4) and adapted to be moved by a ram R. A clamp mechanism (6) is provided for clamping a tip end of the piping material W, which is fitted onto the stationary mandrel (14) to the holder (4a). Incorporated into the shearing type frame (2) rearwardly of the stationary blade (3) is a traction mechanism (7) which acts to grip the piping material W to exert a traction force thereon in an axial direction and which is capable of extending and contracting and moving in an axial direction.

Description

 ■ fe n

 Akira Pipe material precision shearing method and equipment

 The present invention relates to a method and an apparatus for shearing a pipe material to a high-precision cut surface having little unevenness and free from abrasion and burning. Background technology

 Steel materials represented by S45C, S20C, S15C, etc. are widely used as materials for plastic working, but in recent years the purpose is to reduce the number of processes. There is an increasing demand to use short pipe materials instead of solid materials for forging purposes in order to meet the needs. Such short pipe material as a forging material requires not only deformation (crushing) but also a high-precision cut surface without secondary cross sections or large irregularities.

As a method of cutting a pipe material, a parting-off method and a cutting method using a rotary blade are known. However, these methods have poor production efficiency and poor cut face accuracy. On the other hand, the shearing method using a press has good production efficiency, but has a problem that the pipe material is crushed. To prevent this, a precision shearing method using a core metal is known. As a typical example, a method using a floating metal core is proposed in Japanese Patent Publication No. 56-45727. Have been. In this method, a fixed mandrel to be fitted to a pipe material to be cut is provided on the punch side, and a mandrel opposed to the fixed mandrel is put into the pipe material, and the fixed mandrel is used. This is a method of cutting along the surface where the floating core metal comes into contact with the floating core metal. However, when this prior art was implemented, it was possible to solve the problem of crushing, but no improvement in cut surface properties could be expected.

 That is, as a specific example, the present inventors set the tool clearance C to 0.

定、 内径 ：4， 6, 10, 14mm)を、 浮動芯金法に よってせん断速度 V ： 20mm(D.02m)/secの低速度でせん断実験してみ た。 この実験では、 移動刃と固定刃の内径はそれぞれ 22.1關 øとし、 芯金の外径は、 材料（パイプ）との隙間が 0.2圓となるようにパイプ材 内径よりも 0.4關小さい寸法とした。 1 mm—Constant conditions, pipe material of various thicknesses (material: S 45 C, outer diameter 0:

(Inner diameter: 4, 6, 10, 14 mm) was tested by the floating core method at a low shear rate V: 20 mm (D.02 m) / sec. In this experiment, the inner diameter of the moving blade and the fixed blade was 22.1 ° each, and the outer diameter of the core was 0.4 smaller than the inner diameter of the pipe material so that the gap between the material (pipe) was 0.2 round. .

 As a result, scratches were observed in the lower area of the cut surface on the retainer side regardless of the magnitude of d (inside diameter of pipe material) / D (outside diameter of pipe material). On the off-cut side, a cut surface was observed in the upper area of the cut surface, and as the dZD became larger, the irregularities became larger and scratches were also observed. And the scratches were also generated in the lower area on the remainer side to the same extent. FIG. 1 schematically shows a cut surface when d / D = 1022, and FIG. 2 schematically shows a cut surface when dZD = l4 / 22. In FIGS. 1 and 2,

(a) is the offcut side, (b) is the retainer side, A shows unevenness, and B shows scratches.

 Since such irregularities and scratches are inevitable, a short pipe material suitable for forging material cannot be sheared by a floating core metal method as in the prior art.

The present invention has been made in order to solve the above-mentioned problems. The first object of the present invention is to provide a pipe material shearing method capable of obtaining a high-precision cut surface which is not crushed and has no irregularities or scratches.

 A second object of the present invention is to provide a shearing device which is suitable for performing the shearing method and has a relatively simple and compact structure. Disclosure of the invention

 In order to achieve the first object, the present invention provides a method of shearing a pipe material using a metal core, wherein the pipe material is sheared at a high speed with a tensile force applied in the axial direction of the pipe material.

 More specifically, the pipe material into which the floating core is inserted is inserted into the movable blade by a length corresponding to the cut-off length through the fixed blade, so that the fixed core and the floating core are fitted together. This method shears the pipe material by moving the movable blade along the surface where it comes into contact, and clamps the tip of the pipe material inside the movable blade while the fixed core bar and the floating core bar are in contact with each other. The pipe material is pulled in the axial direction, and this axial tension state is continued from the start of shearing until the off-cut portion is sheared off.

 The magnitude of the axial tensile force is 1.5% or more and less than 100% of the yield stress of the material, and the shear rate is generally about 1 m / sec or more.

In the present invention, the pipe material is sheared by using the core metal, so that it is possible to prevent crushing. Moreover, since the pipe material is sheared under tensile stress in the axial direction, the moment the material cracks, the retainer side and off-force side separate from each other in the axial direction to promote crack propagation, and the moment the cracks communicate with each other. , Remain The da side slightly escapes in the axial direction. For this reason, the upper cut surface area on the offcut side is cut off without contacting the lower cut surface area on the retainer side. Therefore, scuffing and burning due to frictional heat can be eliminated.

 Further, in order to achieve the second object, the present invention provides a fixed blade fixed to a shearing type frame and provided with a hole through a pipe material at a predetermined position, a floating core inserted in the pipe material, In a shearing device including a hole through which a pipe material is passed and a movable blade having a fixed core concentric with the hole, and a holder for fixing the movable blade and moving by a ram, the fixed core is fitted to the holder. While providing a clamp mechanism for restraining the tip of the pipe material, the shear-type frame behind the fixed blade is scalable and axially retractable to grip the pipe material and apply traction in the axial direction. The structure incorporates a movable traction mechanism.

 The clamping mechanism preferably comprises a material presser having a presser surface conforming to the contour of the pipe material and a fluid pressure cylinder provided with a screw for moving the material presser.

Preferably, the traction mechanism includes a bottomed hole provided in the shearing type frame concentrically on the material pipe feed line, a cylindrical main body slidably fitted in the bottomed hole, A plurality of material holders slidably inserted into the main body, an elastic member for urging the tubular main body in the direction opposite to the pipe feeding direction, and an elastic member for urging the material holder in the direction opposite to the pipe feeding direction. And an actuator for moving the material retainer in the pipe material feeding direction against the urging force of the elastic member, wherein the cross-sectional area of the inside of the cylindrical main body decreases in the direction opposite to the pipe material feeding direction. Each material retainer has an inner surface with a pipe material It has a concave portion corresponding to the contour, and the outer surface has an inclined surface having an angle corresponding to the inclined surface of the cylindrical main body.

 According to this device, the pipe material can be pulled in the axial direction within the shearing mold close to the shearing part without requiring any special axial tensioning means outside the shearing mold. It can be realized. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is an end view schematically showing the cut surface of the pipe material when low-speed shearing is performed by the conventional floating core method. (A) shows the off-cut side, and (1 shows the re-mainer side.

Figure 2 is an end view schematically showing the cut surface of the pipe when low-speed shearing is performed by the conventional floating core method. (A) shows the offcut side, and (b) shows the retainer side.

FIG. 3 is an explanatory diagram showing a cross-sectional state of the pipe material in the middle of shearing.

FIG. 4 is an enlarged cross-sectional view of each part in FIG. 3 at the initial stage of the tool biting. FIG. 5 is an enlarged cross-sectional view of each part in FIG. 3 at the stage when the tool biting has progressed. Figure 6 is a diagram of the shear load vs. stroke when the pipe material is sheared.

Fig. 7 is an end view schematically showing the cut surface when high-speed shearing is performed by applying an axial compressive force. (A) shows the offcut side, and (b) shows the maintainer side. Fig. 8 is an end view schematically showing a cut surface when high-speed shearing is performed by applying an axial compressive force. (A) shows an offcut side, and (b) shows a retainer side. FIG. 9 is an explanatory view schematically showing the method of the present invention. G

FIG. 10 is a longitudinal sectional side view showing an example of a shearing type suitable for carrying out the present invention. FIG. 11 is a longitudinal sectional front view of a traction mechanism portion in FIG.

FIG. 12 is a longitudinal side view of the stage where the pipe material has been fed into the shearing mold of FIG.

FIG. 13 is a longitudinal side view at the stage when an axial tensile force is applied to the pipe material, and FIG. 14 is a longitudinal side view at the stage of completing the shearing.

Fig. 15 is a graph showing the relationship with the burnt area when the pipe material is sheared by applying an axial tensile force of 0 to 10% of the yield stress. Detailed description of the invention

 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

 First, the present inventors observed the state of the pipe material in the middle of shearing in order to ascertain the cause of the occurrence of the M convexity on the cut surface and the scratches as described above. Fig. 3 to Fig. 5 show the cross section of the pipe material (d / D = 14 to 22) in the middle of shearing. The portions C, E, and F in FIGS. 4 and 5 are the regions shown in FIG.

Figure 4 shows each part at a stage where the bite K of the tool is as low as 5% (outer diameter ratio). At this stage, crack C has already been communicated to the upper part in part C, that is, in the shear direction, and material separation has been performed, whereas in the lower part E in the shear direction, a small portion is located at the position corresponding to the movable blade edge. Despite the occurrence of cracks cr, it has not yet been separated. In addition, no cracks were observed in the F part, that is, the right and left parts orthogonal to the shear direction. Fig. 5 shows each part at the stage when the bite K of the tool increased to 9% (outer diameter ratio), and the parts C and Ε were separated by cracks communicating with each other, while the part F was Although small cracks cr occurred near the edges of the movable blade and the fixed blade, separation has not yet been completed. Fig. 6 shows the results of measuring the shear load stroke, which is closely related to material separation. As is evident from Fig. 6, in the case of solid material with dZD of 0, the shear load decreases sharply from the stroke position where the maximum load has been exceeded, but in the case of pipe material, the shear load decreases after the maximum load position. The phenomenon where the shear load continues to be applied is also observed. Moreover, this phenomenon becomes more pronounced as dZD increases.

 From the above, it can be seen that the material separation mechanism during pipe material shearing is unique. In other words, in solid wood, cracks that have started to develop from both the fixed and movable blade edges instantaneously meet in a very short stroke. On the other hand, in the case of pipe material, cracks that started to occur from both the cutting edge of the fixed blade and the movable blade required a considerably long stroke to grow intermittently, and the C portion of the pipe material was separated first. After that, the part E is separated, and finally the part F is separated.

The F part, which is the left and right part of the pipe hole, is thicker than the C part, which is the upper part, and the relative clearance to the plate thickness during shearing decreases sharply in the F part. Therefore, as can be seen from Fig. 5 (c) (tl), the crack cr that occurs first does not go to the opposite tool edge. In other words, the directions of the cracks do not turn so that they communicate with each other on a straight line, and in this state, Separation takes place. As a result, irregularities A as shown in Fig. 1 and Fig. 2 occur at the left and right cut surfaces of the pipe hole.

 It was also found that the scratch B occurred because the cut surfaces after shearing, that is, the lower portion on the reminder side and the upper portion on the off-cut side were rubbed.

 As a countermeasure, the present invention first decided not only to perform shearing using a floating core, but also to perform high-speed shearing. By adopting this high-speed shear, the direction of the crack can be made to extend almost linearly toward the opposite tool edge, so that a cut surface with a good squareness can be obtained. The shear rate depends on the material and dimensions of the pipe material. Generally, the higher the speed, the greater the effect. For steel, a speed effect of about 1 mZsec or more can be obtained.

However, according to the experiments of the present inventors, when the above-described various d / D pipe materials were sheared with a tool clearance C of 0.1 mm and a shear rate of V = 7 mZsec, they were compared with the above-described low-speed shear. [H-convex became considerably small, but scratches still occurred. Therefore, high-speed shearing alone could not yet achieve sufficient cut surface accuracy. As a countermeasure, the next possibility is to use a shearing method that adds axial compression, which is known as a method for obtaining high-precision cuts in shearing solid materials. Therefore, during the high-speed shearing, shearing was performed by applying an axial compressive stress of 150 N / mm ² to the pipe material from the rear.

FIGS. 7 and 8 schematically show a cut surface obtained by this method of applying an axial compressive force. Fig. 7 shows d / D = 6/22, and Fig. 8 shows dZD = 14/22. In each figure, (a) is the offcut side, and) is the remainer side. is there. As is evident from Figs. 7, 8 and 9, the unevenness of the cut surface is almost eliminated, as in the case of high-speed shearing without the application of axial compressive force. However, large scratches and burns B have occurred.

 From this, it was found that in the case of pipe material shearing, the properties of the cut surface deteriorated when an axial compressive force was applied. Since the burned part is hardened compared to the base metal, it causes non-uniform deformation when used as a forged material, and there is a major problem that cracks occur in the burned part after forging.

 Therefore, the present invention changes the idea and performs the shearing while applying an axial tensile force to the pipe material during high-speed shearing.

 FIG. 9 shows in principle the shearing method according to the invention. W is a pipe material, 2 is a shear frame, 3 is a fixed blade fixed to the shear frame 2, 4 is a movable blade that is moved at a high speed by a ram R, and a fixed blade 3 and a movable blade 3 are pipe materials. Holes 30 and 40 into which W is inserted are provided respectively. A floating core 13 is inserted into the pipe material W, and the floating core 13 is rubbed with a 0 ring or the like so as not to move unnecessarily. Material 130 is provided on the outer periphery. In the hole 40 of the movable blade 4, a fixed core 14 that is in contact with the floating core 13 is located.

With the floating core 13 inserted, the pipe material W is inserted into the hole 40 of the movable blade 4 by the off-cut length, and fitted with the fixed core 14. The floating mandrel 13 comes into contact with the fixed mandrel 14. The movable blade 4 is moved down by the ram R in this state, _c present invention shear is carried out along the perforated contact surface of the floating core bar 1 3 and the fixed core bar 1 4, upon the shear, of the area to be Ofuka' bets Pipe material tip The end portion w is firmly clamped from the direction perpendicular to the pipe axis by the clamp mechanism 6, and in this state, the pipe material W is pulled backward as shown by the arrow, that is, in the anti-fixed blade direction, or in other words, in the pipe feed direction. This tension continues from the start of shearing until the offcut is sheared off.

 Here, the magnitude of the axial tensile force depends on the material, wall thickness, mechanical properties, etc. of the pipe material, but generally it is necessary to be at least 1.5% of the yield stress of the pipe material. . The reason for this is that if the pulling force is less than this, the cut surfaces on the off-force side and the remainer side do not separate sufficiently at the moment of shear separation, making it impossible to reliably prevent the cut surfaces from rubbing or burning. It is.

 However, if the magnitude of the axial tensile force exceeds the yield stress (yield point), the pipe material undergoes plastic deformation before shearing, so the axial tensile force must be less than the yield stress. Also, if the axial tensile force is higher than the yield stress, the clamping force on the off-cut side must also be increased, which may cause deformation such as crushing of the material. Therefore, the upper limit of the tensile force must be less than 100% of the yield stress and the deformation of the material such as crushing does not occur. The specific magnitude of the axial tensile force may be appropriately set according to the material, wall thickness, and mechanical properties of the pipe material to be sheared. FIG. 10 shows an example of a precision shearing device suitable for carrying out the present invention.

1 is a base plate fixed to a press plate or a porter, 2 is a shearing frame fixed to a base plate 1 and has a block portion 2a at the center in the longitudinal direction, and is adjacent to the block portion 2a. A space 2b is formed in the front area of the building. The block portion 2a is provided with a pipe material 揷 through hole 20 extending in the axial direction at a position of a required height level, and a bottomed hole 21 provided concentrically with the pipe material 揷 through hole 20. I have. The opening side of the bottomed hole 21 is closed by a rear wall 2d fixing the supporting wall 2c integrally. The supporting wall 2G and the rear wall 2d are provided with a pipe material through hole 20 concentric with the pipe material through hole 20.

 A feeder 10 of a desired type such as a feed roll is arranged at a height level corresponding to the pipe material insertion hole 20 outside the shearing type frame 1, and the floating core 13 is inserted in advance. The pipe material W is inserted into the pipe material insertion holes 20 and 20 and is advanced by the feeder 10.

 Reference numeral 3 denotes a fixed blade fixed to a front end portion of the block portion 2a with a bolt or the like, which has a through hole 30 concentric with the pipe material through hole 20 and a lower portion than the through hole 30. A recess 31 for discharging the cut is provided. The fixed blade 3 is, of course, replaceable.

Reference numeral 4 denotes a movable blade which moves relatively to the fixed blade 3 with a minute clearance, and a _c- holder 4a held by a block-shaped holder 4a arranged in the cavity 2b projects from the shearing frame 2. It has a pressurized portion 47 and is urged upward by the base plate 1 or a cushion 4b provided in a hole passing through the base plate 1. Above the pressurized portion 47, there is a press slide itself or a ram R which is moved at a high speed by the accelerator attached to the press slide at a high speed.

The movable blade 4 has a through hole 40 of the same diameter as the through hole 30 of the fixed blade 3, The through hole 40 is coaxial with the through hole 30 of the fixed blade 3 when the holder 4a is at the top dead center position. A fixed mandrel 14 is concentrically arranged in the through hole 40, and the tip of the fixed mandrel 14 is aligned with the end face of the movable blade 4, and can abut on the floating mandrel 13. It is like that.

 The holder 4a has a cavity 41 concentric with the through hole 40 at a portion opposite to the movable blade 4, and the opening side of the cavity 41 is closed by an end wall 43. The wall 43 is connected to the holder 4a by a port or the like (not shown) .The base of the fixed core bar 14 extends backward through the end wall 43 and is connected to the end wall 43 by a nut 140. Fixed. A sleeve-shaped stripper 15 is slidably fitted around the outer periphery of the fixed core 14. The stripper 15 has a flange 150 in a region located in the vacant space, and an elastic member typified by a compression spring is provided between the back of the flange 150 and the end wall 43. The stripper 15 is urged toward the fixed blade 3 by the elastic member 16 so that one end of the strip bar is aligned with the end face of the movable blade 4 in a normal state. I have. The elastic member 16 is set to have a spring force weaker than the feed force of the feeder 10.

A sensor 4d is attached to the end wall 43 at a position facing the flange 150. The sensor 4d uses a contact-type switch or the like, and is electrically connected to an external controller (not shown). The sensor 4d is configured such that the tip of the pipe material W comes into contact with the tip of the stripper 15 by the feeder 10, and the stripper 15 is piled on the pressing force of the elastic member 16 and retreated. Turns on when it comes into contact with the rear of 50, and sends a signal to the controller. The controller consists of a feeder ι ο, a ram, and a clamp mechanism described later.

The output side is electrically connected to each drive source or drive control element (for example, an electromagnetic switching valve) to control the operation of the traction mechanism 6 and the traction mechanism 7 according to a predetermined program.

 Reference numeral 5 denotes a device for applying an axial tensile force to the pipe material W, and a clamping mechanism 6 for a tip region of the pipe material W; Traction mechanism 7.

 More specifically, the clamp mechanism 6 presses the distal end region of the pipe material ahead of the shear position from a direction perpendicular to the axis to restrain the movement of the pipe material, and may be incorporated in the movable blade 4. Although it is good, it is preferably provided in the holder portion below the movable blade 4.

 The clamp mechanism 6 is composed of a material holder 60 slidably inserted into a hole 63 intersecting the through hole 40 at a right angle, and an actuator for moving the material holder. In this embodiment, the actuator is an air cylinder or the like. Fluid pressure cylinders are used. That is, the piston 61 located in the bore 64 having a larger sectional area than the hole 63 and connected to the material retainer 60, and the piston 61 disposed in the bore 64 are constantly biased to the restraining release side. A return spring 62 is provided, and a pipe for supplying fluid is connected to a bore 64 below the piston 61. The material presser 60 has a concave press surface corresponding to the contour of the pipe material W at the upper end.

The traction mechanism 7 includes a tubular body 8 slidably fitted in a guide hole 210 formed in the inner surface of the bottomed hole 21, and a slidably fitted inside of the tubular body 8. Sa It has a plurality of wedge-shaped material holders 9, 9.

 The tubular main body 8 preferably has a rectangular box-shaped cross section as shown in FIG. 11, and is normally urged rearward, that is, in the counter-feed direction from the elastic member 12. In this embodiment, a tension spring is used as the elastic member 12, and connects between the rear end face of the cylindrical main body and the support plate 2c. Instead, a compression spring may be used and may be interposed between the front end surface of the cylindrical main body 8 and the bottom of the bottomed hole 21. The inner surface of the cylindrical main body 8 is formed with an inclined surface 81 so that the cross-sectional area becomes gradually smaller toward the rear in the axial direction, and has an inner flange-shaped stopper 80 at the front end.

 In this embodiment, the material retainers 9 and 9 are formed of two pieces, each having a predetermined length so as not to locally deform the pipe material at the time of gripping, and a concave portion corresponding to the contour of the pipe material W on each inner surface. 90, and the outer surface has an inclined surface formed at an angle corresponding to the inclined surface 81.

The material retainers 9 and 9 are urged by a resilient member 9a disposed on the bottom wall of the bottomed hole 21 such as a compression spring toward the tightening side, that is, the cross-sectional area reducing side of the cylindrical body 8. . A tensile force of not less than 1.5 o / _{0 of the} yield stress is given by the elastic member 9a. Therefore, an arbitrary tensile force can be obtained by selecting the spring constant of the elastic member 9a to be used.

 In this embodiment, several elastic members 9a are used for each of the material retainers 9, 9, but all the material retainers 9, 9 are attached using a single cylindrical coil spring or disc spring. You may make it go.

The inclined surface of the cylindrical body 8 or the inclined surfaces of the material retainers 9 and 9 are preferably made of metal or a sheet having a low friction coefficient for smooth relative sliding. Bearing elements 92 are provided.

 The supporting wall 2c is provided with an actuator 11 for expanding the material pressers 9, 9. The actuator 11 is, for example, a hydraulic cylinder, and the operating rods 110, 11 (1 are connected to or abut on the rear ends of the material holders 9, 9). In the embodiment, the material is held in a ring shape because it is shared by the material pressers 9 and 9. However, the shape is not limited to this and may be various.

 In this embodiment, two material retainers 9 and 9 are arranged vertically, and as shown in FIG. 11, springs 93 and 9 are provided between the material retainers 9 and 9 to urge them in the separating direction. 3 are interposed. However, when the material pressers 9 and 9 are displaced 90 degrees from those shown in the figure, that is, on the left and right sides, the springs 93 and 93 are not necessarily required.

 The elastic members 9a, 12 and 16 may be made of a compressible material such as urethane rubber or a hydraulic cylinder having a cushioning property such as an air cylinder.

 Next, a shearing method to which the present invention is applied will be described. The shear stroke is shown in FIG. 10 and FIGS. 12 to 14.

For shearing, first, with the floating core 13 inserted in the pipe material W, the pipe material W is inserted from the pipe material insertion holes 20 and 20 through the material retainers 9 and 9. The state at this time is shown in FIG. 10. Since the stripper 15 is pressed from behind by the elastic member 16, the tip of the stripper is located at a position matching the end face of the fixed core 14, and the pipe material W The tip surface is in contact with the strip bar—tip. Floating mandrel 13 presses air from behind pipe material W 1

The fixed core 14 is brought into contact with the fixed core 14 by inserting or pecking with a stick or the like. At this time, both the actuator 11 and the actuator of the clamp mechanism 6 are not operating, and the material retainers 9, 9 are pressed by the elastic members 9 a and positioned in the minimum cross-sectional area of the cylindrical main body 8. I have. Also, the holding surface of the material holder 60 is lightly in contact with the outer surface of the stripper 15 or is in a non-contact state.

 Next, when the actuator 11 is operated in this state, the material holders 9, 9 are pressed by the operation rods 110, 110 being advanced as shown in FIG. 12, and the elastic members 9a are attached. The pipe material W moves forward along the tapered surface 81, that is, in the pipe material feeding direction, against the force, and the material pressers 9, 9 are expanded, whereby the pipe material W is released from the constraint. Since the material retainers 9 and 9 come into contact with the stopper 80 of the cylindrical main body 8 when moving, the cylindrical main body 8 resists the force of the elastic member 12 until it comes into contact with the base end face of the guide hole 210. And are forcibly moved.

 By operating the feeder 10 in this state, the pipe member W is advanced, and the tip of the pipe member W enters the through hole 40 from the end face position of the movable blade 4. The stripper 15 which is in contact with the tip of the pipe material W retreats against the biasing force of the elastic member 16 and the rear end flange 150 contacts the sensor 4d. As a result, the sensor 4d is turned on, and the signal is sent to the drive unit of the feeder 10 via the controller to stop the driving, so that the pipe member W is set.

When the stripper 15 comes into contact with the sensor 4d and is turned on as described above, the drive signal is sent from the controller to the drive system of the clamp mechanism 6. Is sent. In this embodiment, since a fluid pressure cylinder is used as an actuator, the electromagnetic switching valve of the fluid supply circuit is switched, and a pressurized fluid, for example, compressed air is supplied to the bore 64. As a result, as shown in FIG. 13, the material presser 60 moves in the hole 63, so that the tip end region of the pipe material in the through hole 40 of the movable blade 4 is restrained from a direction perpendicular to the axis.

 Slightly later than this, the operation of the actuator 11 is turned off by a signal from the controller. In this example, since a fluid pressure cylinder is used as the actuator 11, the solenoid switching valve is switched to release the cylinder pressure.

 As a result, the compression load on the elastic member 9a is released, so that the material pressers 9, 9 move rightward, that is, in the direction opposite to the pipe feeding direction, along the tapered surface 81 by the reaction force of the elastic member 9a. As a result, the material retainers 9 and 9 are reduced in diameter, and the pipe material W is firmly bound from the outer periphery by the approaching material retainers 9 and 9.

 At the same time, the cylindrical body 8 is released from the position holding state by the above-mentioned movement of the material retainers 9, 9, and is moved rightward, that is, in the anti-pipe material feeding direction by the force of the elastic member 12. As a result, the material retainers 9 and 9 further move in the anti-pipe material feeding direction. For this reason, the pipe material W whose tip is clamped by the clamp mechanism 6 as described above is forcibly pulled in the axial direction, and an axial tensile force of 1.5% or more of the yield stress is applied.

The ON signal of the sensor 4d is also sent to the drive section of the press via the controller, whereby the ram R is driven at a high speed. State with directional tensile force applied The pipe material W is sheared by the movable blade 4.

 This shearing proceeds as described above by a mechanism in which the upper part of the pipe material W separates, then the lower part separates, and finally the left part separates.However, since the shear rate is high as lm / sec or more, The cracks that occur after the shear surface has been formed with anyone will be communicated within the short stroke. In addition, the crack extends linearly toward the opposite tool edge. For this reason, the degree of unevenness on the cut surface is reduced.

 Moreover, during the shearing process, the pipe member W is forcibly applied with an axial tensile force of 1.5% or more of the yield stress by the clamping mechanism 6 and the pulling mechanism 7. For this reason, at the moment when a crack is formed after the shear surface is formed, the retainer side and the off-force side are separated in the axial direction so as to promote the propagation of the crack. The side slightly escapes in the axial direction. For this reason, the upper area of the cut surface on the offcut side does not come into contact with the lower area of the cut surface on the retainer side, and abrasion due to rubbing is prevented. Also, there is no burning due to frictional heat.

After the material is separated, the operation of the actuator of the clamp mechanism 6 is turned off as shown in FIG. 14, and the restraint on the off cut side is released. When the movable blade 4 descends and the fixed core metal 14 reaches the position corresponding to the concave portion 31 of the fixed blade 3, the stripper 15 moves forward by the reaction force of the elastic member 16 and is cut off. W 'is discharged outside the mold. Next, when the ram R rises, the movable blade 4 is returned by a pushing force of the cushion 4b until a predetermined position, that is, the through holes 40, 30 of the movable blade 4 and the fixed blade 3 become concentric, whereby The state shown in Fig. 10 is reached. Hereinafter, by repeating the above-described series of operations, it is possible to obtain a high-precision cut surface without crushing, with small unevenness, and without scratches. Examples Examples

Next, examples of the present invention will be described.

 Example 1

 Using the equipment shown in Fig. 10 and Fig. 11, four types of steel pipes with an outer diameter of 22 round ø and an inner diameter of 10 mm ø are sheared at an off-cut length of 40 mm at a shear rate of 0.02 to 7 m / sec. did.

 The shearing conditions were as follows: the outer diameter of the floating core was 9.6 mm, the inner diameter of the tool (movable blade and fixed blade) was 22.1 mm, and the clearance between the fixed blade and the movable blade was 0.1 mm. Shearing was performed by applying an axial tensile stress equivalent to 2.5% of the yield stress of each material by the clamping mechanism and the traction mechanism.

Table 1 shows the results. In Table 1, X indicates poor and perpendicularity failure, Δ indicates good crushing and perpendicularity, but has unevenness, O indicates small and good unevenness, and ◎ indicates best with smooth fractured surface. Neither scuff nor scorch occurred. It can be seen that good shearing is performed when the shear rate is 1 m / sec or more. O

ο

2 丄

 Example 2

 Using the apparatus shown in Fig. 10 and Fig. 11, S 45 C pipe material with an outer diameter of 22 mm0 and an inner diameter of 10 mm ø was sheared at an off cut length of 40 mm at a shear rate of 1. Om / sec.

 The shear conditions were as follows: the outer diameter of the floating core was 9.6 mm, the inner diameter of the tool (movable blade and fixed blade) was 22.1 mm, and the clearance between the fixed blade and the movable blade was 0.1 mm. Shearing was performed while applying an axial tensile stress equivalent to 0 to 10% of the yield stress of the material.

The result is shown in FIG. On the shear surface, the presence or absence of burns that can be visually judged is li i ² or more. In Fig. 15, it can be seen that by applying an axial tensile force equivalent to 1.5% or more of the yield stress of the material, burning due to shearing can be prevented.

 Under the above shearing conditions, when the axial tensile stress was set to 0.5% of the tensile stress of the material, some filings were observed. No outbreak was observed.

 Based on the above results, in addition to using the core metal, when shearing at a shear rate of lm / sec or more and applying an axial tensile force of 1.5% or more of the yield stress of the material, shearing is reduced, and It can also be seen that a high-precision cut surface without scratches or burns can be obtained. Industrial applicability

INDUSTRIAL APPLICABILITY The method and apparatus for precision shearing pipe material of the present invention are suitable as a method for obtaining a pipe material having a desired length used as a material for forging. Applicable in any case where a degree cut face is required. Shearing targets include nonferrous metals such as aluminum and its alloys, copper and its alloys, titanium and its alloys, as well as iron-based pipes represented by S45C, S20C, S15C, etc. Is also applicable to non-metallic pipes.

Claims

The scope of the claims 1. A precision shearing method for pipe material, wherein the pipe material is sheared using a core metal, and high-speed shearing is performed with a tensile force applied in the axial direction of the pipe material.  2. The method according to claim 1, wherein the tensile force in the axial direction is 1.5% or more and less than 100% of the yield stress of the material, and the shear rate is lm / sec or more.  3. Insert the floating core (13) inside the pipe (W) through the fixed blade (3) and insert it into the movable blade (4) by the length of the off-cut into the movable core (4). 14) and shearing the pipe material by moving the movable blade (4) along the surface where the fixed core (14) and the floating core (13) meet. With the fixed core metal (14) and the floating metal core (13) in contact with each other, clamp the pipe material tip area inside the movable blade (4) and pull the pipe material (W) in the axial direction. 3. The method for precision shearing pipe material according to claim 1, wherein the method is continued from the start of shearing until the output portion is sheared off. 4. A fixed blade (3) fixed to the shearing frame (2) and provided with a hole (30) through the pipe (W) at a predetermined position, and a floating core inserted in the pipe (W) A movable blade (4) having a metal (13), a hole (40) passing through the pipe material (W) and a fixed core (14) concentric with the hole (40), and a movable blade (4) fixed to the ram (R) ), The tip of the pipe (W) fitted to the fixed core (14) is fitted to the holder (4a). While the clamp mechanism (6) for restraining is provided, the pipe material (W) is gripped in the shearing frame (2) behind the fixed blade (3) to apply traction in the axial direction. A precision shearing device for pipes, which incorporates a traction mechanism (7) that is scalable and movable in the axial direction. 5. The clamp mechanism (6) is composed of a material presser (60) having a presser surface conforming to the contour of the pipe material and an actuator for moving the material presser (60), and the traction mechanism (7) is a material pipe feeder. A bottomed hole (21) provided in the shearing frame (2) concentrically with the line, and a cylindrical body (8) slidably fitted in the bottomed hole (21); A plurality of material retainers (9) inserted into the cylindrical body (8) so as to be relatively slidable; an elastic member (12) for urging the cylindrical body (8) in a direction of feeding the pipe material; An elastic member (9a) that urges the material retainer (9) in the direction opposite to the pipe material feed direction, and moves the material retainer (9) in the pipe material feed direction by staking the urging force of the elastic member (9a). The cylinder body (8) is provided with an actuator (11) for expanding the material presser (9), and the inside of the cylindrical body (8) is inclined (8) so that the cross-sectional area decreases in the direction opposite to the pipe feed direction. Each material presser (9) has a concave portion corresponding to the contour of the pipe material on the inner surface, and the outer surface has an angle corresponding to the inclined surface (81) of the cylindrical main body (8). 5. The precision shearing device for pipe material according to claim 4, wherein the device has an inclined surface.  6. The precision shearing device for pipe material according to claim 5, wherein the elastic member (9a) for urging the material retainer (9) in a direction opposite to the pipe material feeding direction is a tension spring.  7. The precision shearing device for pipe material according to claim 5, wherein the actuator of the clamp mechanism (6) is a hydraulic cylinder. 8. Hold the vacant space (4 1) closed by the end wall (43) with the holder (4a) The fixed core (14) has a proximal end fixed to the end wall (43). A sleeve-like stripper (15) is slidably fitted on the outer periphery of the fixed core (14), and the strip (15) is a portion located in the empty chamber (41). The stripper (15) has a front end movable in a normal state by being urged by an elastic member (16) disposed between the flange (150) and the end wall (43). 6. The precision shearing device for pipe material according to claim 4 or 5, including one protruding to a position matching the end face of the blade (4). 9. The holder (4a) has an empty space (41) closed by the end wall (43) on the non-movable blade side, and the base end of the fixed core (14) is fixed to the end wall (43). ing. A sleeve-shaped stripper (15) is slidably fitted around the outer periphery of the fixed cored bar 14, and the stripper (15) has a flange (150) at a portion located in the empty chamber (41). When the flange (150) is urged by the elastic member (16) disposed between the flange (150) and the end wall (43), the tip of the stripper (15) normally contacts the end of the movable blade (4). When the stripper (15) retracts along with the feed of the pipe material (W) on the end wall (43), at least the clamping mechanism (6) and the traction mechanism ( 6. The pipe material precise shearing device according to claim 4, including a device provided with a sensor (4d) for sending a drive signal to 7).