RU2094148C1 - Pipe pressing method and apparatus - Google Patents

Abstract

FIELD: plastic working of metals, in particular, production of pipe on presses operating without piercing system. SUBSTANCE: method involves mounting centering sleeve in die; positioning mandrel into central opening of billet; placing billet in container of press; mounting washer; centering rear end of mandrel in pressing washer and front end in centering mandrel; pressing pipe into gap between mandrel and die. Apparatus has container, die, pressing washer, process washer, loose detachable connection and movable mandrel with stepped shank and centering sleeve. Stepped shank has cylindrical step of predetermined diameter and cylindrical rear end. Front and rear ends of mandrel are beveled. Spring is positioned adjacent to working part of mandrel. Centering sleeve is made in the form of conical spring with regulated diameters. Front end of pressing washer has annular concave portion. Curvature of this portion depends on that of die opening. End surface of process washer adjoining to pressing washer is equally spaced from curved portion, which is provided with variable section channels having regulated depth. Detachable connection may be formed as sleeve for loose joining of pressing washer with movable punch. Contacting surfaces of pressing washer and punch are made spherical. Die is rigidly fixed in immovable container. Detachable connection may be formed as ring adapted to connect die with immovable hollow punch. Pressing washer is fixed in movable container. EFFECT: increased efficiency, simplified method and construction and improved quality of pipes. 6 cl

Description

 The invention relates to the processing of metals by pressure and can be used to produce pipes on presses without a piercing system.

 A known method of producing thin-walled seamless pipes, comprising installing a movable mandrel in a tubular workpiece, placing the workpiece in a press container, sealing the gap between the die and the container, extruding the pipe into the gap between the die and the mandrel under the action of high-pressure fluid acting on the rear end of the mandrel (ed. St. USSR N 237786, class B 21 C, 1969).

 A device for implementing this method is known, containing a container, a conical matrix, a movable mandrel with a shank serving as a guide head, centered on the inner channel of the container and having an axial channel for passing high pressure liquid to the side surface of the workpiece (ed. St. USSR N 237786, class B 21 C, 1969).

 A disadvantage of the known method for producing pipes and a device for its implementation is the low yield, low productivity of the process and limited scope.

 A known method of hot pressing pipes, comprising installing a sleeve on the rear end of the mandrel to the shank of the centering cup on the front end of the mandrel, installing a movable mandrel in the Central hole of the heated billet, placing the workpiece in the press container, centering the front end of the mandrel with the glass in the matrix and pressing the pipe into the gap between the matrix and the mandrel under the action of the stroke of the stamp (ed. St. USSR N 1530278, CL B 21 C 23/04, 1989) prototype.

 A device for hot pressing pipes containing a container, a conical matrix, a press washer and a movable mandrel with a shank, equipped with a sleeve located at the shank, and a cylindrical centering glass worn on the front end (ed. St. USSR N 1530278, class B 21 C 23/04, 1989) prototype.

 The advantages of this method and device include the possibility of increasing the length of the container and the workpiece to 1/2 of the stamp stroke compared to 1/3 of the stamp stroke in other solutions.

 The disadvantages are the formation of a pressure switch and the low accuracy of the rear end of the pipe, which reduces the yield. The disadvantages also include the difficulty of extracting the mandrel after pressing, which makes it fundamentally impossible to use non-tube-type production presses for pressing pipes, although such a need arises at present with the current state of the industry.

 The objective of the invention is to increase the yield when pressing pipes, including when using equipment (presses) of non-tubular production.

 In the practice of the invention, the exact alignment of the mandrel along the axis of the pressing is achieved during the entire deformation process, the formation of a press residue is prevented, the hydrodynamic shock is suppressed at the time of pressing and the subsequent separation of the mandrel from the pressed pipe is simplified.

 The proposed method and device provide both direct and reverse pressing of pipes on equipment that is not related to pipe production.

 The proposed method of pressing pipes includes installing the mandrel in the Central hole of the workpiece, placing the workpiece in the press container and pressing the pipe into the gap between the matrix and the mandrel.

 Unlike the prototype, a centering cup is pre-installed in the matrix, after placing the mandrel in the workpiece, a technological washer is put on it, and before pressing, the rear end of the mandrel is centered in the press washer and the front in the centering cup.

 This method is carried out in a device containing a container, a matrix, a press washer and a movable mandrel with a shank, equipped with a centering glass.

 Unlike the prototype, the mandrel shank is made stepped in the form of a cylindrical protrusion, the diameter of which is greater than the diameter of the working part of the mandrel, but less than the diameter of the hole of the matrix, and continues the working part of the mandrel of the cylindrical rear end. At the front and rear ends of the mandrel, conical shaped sections are made. The centering cup is made in the form of a conical spring cup, the outer diameter of the open end of which is larger than the diameter of the matrix hole by the amount of springing, and the inner diameter is larger than the diameter of the working part of the mandrel also by the amount of springing. The mandrel is equipped with a spring adjacent to the cylindrical protrusion from the side of the working part.

 An annular curved concave section is made at the front end of the press washer, the angle between the tangent to the generatrix of which and the pressing axis at any point is less than or equal to the angle between the tangent to the generatrix of the curved convex surface of the matrix hole and the pressing axis at the corresponding point.

на торце пресс-шайбы до нуля на расстоянии 0,2 0,1 высоты криволинейного участка,
где h_max- максимальная глубина канавки, мм;
d_ц.в. диаметр цилиндрического выступа хвостовика оправки, мм;
d_з.к. диаметр заднего конца оправки, мм.On the curved section of the press washer, grooves of variable cross section are made, the depth of which decreases from the maximum

at the end of the press washer to zero at a distance of 0.2 0.1 the height of the curved section,
where h _max is the maximum depth of the groove, mm;
d _t.v. the diameter of the cylindrical protrusion of the mandrel shank, mm;
d _c.c. diameter of the rear end of the mandrel, mm

 The device is equipped with a technological washer, the rear end surface of which is equidistant to the adjacent front end surface of the press washer adjacent to it.

 The device is equipped with a free detachable connection.

 In a device designed for direct pressing, a detachable connection connects the press washer with the punch. It is made in the form of a screw and has 4 degrees of freedom. The contacting surfaces of the press washer and punch are made spherical. The matrix in this case is rigidly fixed in a stationary container.

 In a device designed for back pressing, a detachable connection connects the die with a stationary hollow punch. It is made in the form of a ring and has 4 degrees of freedom. In this case, the press washer is rigidly fixed in the movable container.

 The proposed method and device for its implementation provide high accuracy of centering the mandrel in the container even before being pressed, at the initial moments of movement of the punch, and maintaining the achieved accuracy of centering of the mandrel along the pressing axis during the entire deformation process. In this case, a complete extrusion of the workpiece metal into the pipe is achieved and, at the end of the process, shock absorption (blanking) of the hydrodynamic shock is achieved, and after the end of the pipe exits the matrix, the mandrel spontaneously separates from the finished pipe.

 The execution of the centering cup conical with an outer diameter of the open upper end exceeding the diameter of the hole of the matrix, and the installation of the cup in the hole of the matrix before loading the workpiece assembly, when pulling the mandrel onto the cup, the inner diameter of the open end of which exceeds the diameter of the mandrel, to capture and due to the springing properties of the glass that also hold it in the matrix, immediately accurately center the front end of the mandrel along the axis of the matrix until the front end of the tube exits the gauge belt of the matrix.

 The execution of the mandrel shank in steps, with a cylindrical rear end with a diameter greater than the diameter of the working part of the mandrel, but smaller than the diameter of the matrix hole, and with a length exceeding the height of the technological washer, makes it possible to center the rear end of the mandrel in the press washer after installing the technological washer already at the moment of sliding mandrel.

 The presence of lead-in conical sections at the front and rear ends of the mandrel makes it easy to pair with other elements of the device.

 In direct pressing, the spherical shape of the rear end of the press washer in contact with the punch surface reflected by it, and the loose connection of the press washer with the punch by a fastener (detachable connection) made in the form of a screw having two degrees of freedom in translational and two in rotational directions , while simultaneously rigidly installing the matrix in the container, they provide self-installation of the press washer along the internal channel of the container. Due to this, the press washer is centered along the pressing axis already at the initial moments of the punch movement, even before being pressed, and its self-centering is constant during the pressing process, which ensures the high accuracy of centering the rear end of the mandrel along the pressing axis during the entire pressing process.

 During back pressing, the matrix is freely connected with the stationary hollow punch by means of a fastening element (detachable connection) made in the form of a ring having four degrees of freedom, with the press washers rigidly fixed in the movable container, the matrix is self-mounted on the container and the spring cup is centered along the pressing axis at the initial moments of movement of the container, even before being pressed, and its constant self-centering in the process of pressing, which ensures the preservation of high accuracy centriro pressing the front end of the mandrel along the pressing axis during the entire pressing process.

 The execution on the front end of the press washer of a circular section of curvilinear concave shape, the generatrix of which is in a certain predetermined dependence on the generatrix of the convex surface of the matrix, and the execution of the rear surface of the technological washer of the equidistant said front surface of the press washer leads to the potential energy released at the moment the end of the pressing process, it is spent on extruding the technological washer, as a result of which hydrodynamic shock is amortized.

 The grooves of the regulated form made on the surface of the press washer provide more rapid shock absorption.

 The number and total transverse area of the grooves at the end of the press washer are selected depending on the physical properties of the pipe material and the process washer and constitute the know-how of the invention.

 The installation of a technological washer of a certain shape, depending on the shape of the press washer, in addition to damping the hydrodynamic shock, prevents the formation of a press residue and facilitates the separation of the mandrel and the finished pipe.

 A spring located on the working part of the mandrel and adjacent to the cylindrical protrusion of the shank is compressed during pressing. And after the back end of the pipe exits the matrix (under the influence of the pressed washer material), the compressed spring pushes several millimeters from the mandrel due to the stored potential energy, which simplifies the subsequent extraction of the mandrel.

 Comparison of the proposed method and device with known technical solutions shows compliance with the eligibility criteria of the invention of "novelty."

 The proposed set of essential features of the invention, considered relative to the existing level of technology, shows compliance with the eligibility criteria of the invention "inventive step".

 In FIG. 1 shows a device for direct pressing of pipes at the beginning of pressing; in FIG. 2 end of pressing; in FIG. 3 mandrel; in FIG. 4 is a view AA in FIG. one; in FIG. 5 is a view of BB in FIG. 4; in FIG. 6 is a view BB of FIG. one; in FIG. 7 device for back pressing pipes.

 The pipe pressing device comprises a container 1, a die 2, a press washer 3, and a movable mandrel 4 with a shank provided with a centering cup 5.

The mandrel 4 includes a working part 6 of variable cross section with a tapered inlet front end 7 and a stepped shank consisting of a cylindrical protrusion 8 and a cylindrical rear end 9 with a conical rear portion 10. The mandrel is equipped with a spring 11 located on its working part near the cylindrical protrusion 8 , and a centering conical spring cup 5 installed in the hole of the matrix 2. The diameter of the cylindrical protrusion d _{C. C.} less than the diameter of the calibrating hole of the matrix d _m

The outer diameter of the open end of the glass d $\genfrac{}{}{0ex}{}{\text{n}}{\text{st}}$ more than the diameter of the calibrating hole of the matrix d _m by the amount of springing, and the inner diameter d $\genfrac{}{}{0ex}{}{\text{dy}}{\text{st}}$ more than the diameter of the working part of the mandrel d _op also by a given amount of springing.

где d_ц.в. диаметр цилиндрического выступа хвостовика оправки, мм;
d_з.к. диаметр заднего конца оправки, мм.The press washer 3 and the front and rear end surfaces are made of complex shape. The front end has a flat section 12 and an annular curved concave section 13, the angle α between the tangent and the generatrix of which and the pressing axis at any point is less than or equal to the angle b between the tangent to the generatrix of the curved convex matrix surface 14 and the pressing axis at the corresponding point. On the curved section 13 of the press washer grooves 15 are made of variable cross section. The depth of the grooves on the end face 12 of the press washer is

where d _t.v. the diameter of the cylindrical protrusion of the mandrel shank, mm;
d _c.c. diameter of the rear end of the mandrel, mm

 At a distance l of 0.2 0.1 of the height L of the curved section 13, the depth of the groove 15 goes to zero.

 In the device for direct pressing of pipes (Fig. 1 and 2), the rear end 16 of the press washer 3 is made spherical, the press washer 3 is freely connected to the movable punch 17 by a detachable connection made in the form of a screw 18. The matrix 2 is rigidly mounted in a stationary container 1 In the device for back-pressing pipes (Fig. 7), the matrix 2 is freely connected to the stationary hollow punch 17 of the detachable connection, made in the form of a ring 19. The press washer 3 is rigidly fixed in the movable container 1.

 The device is equipped with a technological washer 20, the rear end surface of which is equidistant to the front end surface of the press washer 3.

 The proposed method of pressing pipes is as follows.

 The centering spring cup 5 is placed in the matrix 2. The mandrel 4 together with the spring 11 is installed in the opening of the workpiece 21 and the technological washer 20 is put on. The assembly is placed in the container 1. The back end of the mandrel 9 is centered by the initial movement of the mandrel 9 in the press washer 3 along the container and the front the end of the mandrel in the glass 5 on the matrix 2. As a result, the workpiece 21 is set strictly along the pressing axis. Then, the pipe 22 is pressed and finally pressed into the gap between the matrix 2 and the mandrel 4. The centering cup 5 is held in the matrix 2 due to springing until the front end of the pipe 22 exits the gauge belt of the matrix. In the process of direct pressing, the press washer 3 self-installs along the container 1 and, as a result, the rear end of the mandrel is self-centered along the pressing axis. In the process of back-pressing, the matrix 2 self-installs along the container 1 and, as a result, the front end of the mandrel is self-centered along the pressing axis.

 During the pressing process, the force is transmitted to the rear end of the pipe billet (checkers) 21 through the technological washer 20, the cylindrical protrusion 8 of the mandrel and the spring 11. At the end of the pressing process, the rear end of the pipe 22 is pressed out through the hole of the matrix 2 under the action of the material of the technological washer 20. After the rear the end of the pipe 22 and the cylindrical protrusion 8 of the mandrel from the matrix 2, the pipe is separated from the working part of the mandrel under the action of the spring 11.

 The industrial applicability of the proposed method and device for pressing pipes is confirmed by the following example of a specific implementation.

 The D6150M press with a force of 10,000 tf is designed for pressing consumable electrodes from a titanium sponge. The press does not have a piercing system and devices for separating the press residue, which does not allow the production of pipes by known methods.

 Using the proposed method and device allows you to extrude pipes without changing the design of the press and retrofitting it with special devices.

 In accordance with the proposed method, a Ti-3Al-2.5V ⌀ 370 mm alloy billet having a central (axial) hole of o 152 mm is loaded into the container after installation of a centering cup of o 193 mm in the matrix o 190 mm. Then, a mandrel o 150 mm is installed in the central hole of the workpiece, the front end of which is placed in a centering cup having o 153 mm. Then install the technological washer (copper-graphite). The container is mounted on the pressing axis and, when the punch is moved, the press washer is self-mounted on the walls of the container and then, with the further movement of the punch, the rear end of the mandrel shank is installed along the opening of the press washer and, accordingly, the axis of the container. Next, the billet is pressed out without difference and the pipe is pressed. The front end of the pipe passing through the gauge ring of the matrix pushes the centering cup, while the front end remains centered in the matrix and the rear end in the press washer. By further moving the press washers, the entire volume of the workpiece is pressed into the pipe. The mandrel is extruded after the pipe under the action of the material of the technological washer extruded through the grooves in the press washer, while the possibility of water hammer is simultaneously eliminated. At the end of pressing, thanks to the spring, the finished pipe is removed from the mandrel, and the punch with the press washer is removed with the press from the container, and the remainder of the process washer during subsequent pressing is a grease washer. Then the container is shifted from the axis of pressing and the pressing process is repeated. Implementation of the proposed method allows to increase the length of the workpiece up to 800 mm and produce extruded titanium pipes weighing up to 300 kg.

 When using known methods with a fixed mandrel, the length of the workpiece does not exceed 500 mm, and the weight of the pressed pipes is 200 kg.

 The assembly of the proposed device can be carried out both on the extrusion line and outside the extrusion line. In the latter case, the length of the workpiece can be increased to 0.8 0.9 the length of the stroke of the punch.

 Thus, the invention provides an increase in yield when pressing pipes on presses without a piercing system and makes it possible to use any non-tube-type presses, both horizontal and vertical, for example, vertical presses for pressing electrodes for vacuum arc remelting of metals with the implementation of direct and reverse pressing methods.

Claims (6)

 1. The method of pressing pipes, including installing the mandrel in the Central hole of the workpiece, placing the workpiece in the press container and pressing the pipe into the gap between the die and the mandrel, characterized in that the centering cup is installed in the matrix first, after placing the mandrel in the workpiece, a technological washer is put on it and before pressing, the rear end of the mandrel in the press washer and the front in the centering cup are centered.  2. A device for pressing pipes containing a container, a matrix, a press washer and a movable mandrel with a shank, equipped with a centering cup, characterized in that it is equipped with an additional technological washer, the end surface of which adjacent to the press washer is equidistant to the latter and free detachable connection, the mandrel shank is made stepwise in the form of a cylindrical protrusion, the diameter of which is larger than the diameter of the working part of the mandrel, but less than the diameter of the matrix hole, and the cylindrical rear end of the def wakes, and the front end of the working part and the rear end of the mandrel have conical sections, the centering cup of the mandrel is made in the form of a conical spring cup, the outer diameter of the open end of which is larger than the hole diameter by the amount of springing and the inner diameter is larger than the diameter of the working part of the mandrel by the amount of springing, the front end of the press washer has an annular curved concave section, the angle between the tangent to the generatrix of which and the axis of pressing at any point is less than or equal to the angle ezhdu tangent to the generatrix of the curved convex surface of the die opening and the extrusion axis at the corresponding point.  3. The device according to p. 2, characterized in that the detachable connection is made in the form of a screw and freely connects the press washer with a movable punch, the contacting surfaces of the punch and press washers are made spherical, and the matrix is rigidly mounted in a stationary container.  4. The device according to p. 2, characterized in that the detachable connection is made in the form of a ring and freely connects the matrix with a stationary hollow punch, and the press washer is rigidly fixed in a movable container. 5. The device according to any one of paragraphs.2 to 4, characterized in that on the curved concave section of the press washer grooves of variable cross section are made, the depth of which decreases from the maximum, established from the ratio

at the end of the press washer to zero at a distance of 0.2 0.1 the height of the curved section,
where h _{m a x} groove depth, mm;
d _{c . in.} the diameter of the cylindrical protrusion of the mandrel shank, mm;
d _{s. k.} diameter rear end of the mandrel, mm.  6. The device according to any one of paragraphs.2 to 5, characterized in that the mandrel is equipped with a spring adjacent to its cylindrical protrusion from the side of the working part.

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