RU2108881C1 - Method and hydraulic press for hot extrusion of hollow products at active action of friction forces - Google Patents

Abstract

FIELD: plastic metal working, namely hot extrusion of hollow products widely used in aircraft construction, chemical machine engineering, ship making and so on. SUBSTANCE: method comprises steps of heating hollow blank, placing it in sleeve of container into which through cavity of said blank needle is passed; extruding blank by means of short extrusion ram through annular gap restricted by die hole and said needle and determining shape and dimension of ready product; at extrusion process sustaining ratio of container motion speed Vc to motion speed Vr of short extrusion ram equal to 1.01 -1.4, ratio of needle motion speed Vm to Vr equal to 1.01 -1.05, ratio of Vc to Vm equal to 1.02-1.33. Hydraulic extrusion press includes frame, front and rear cross pieces, container mounted with possibility of reciprocation motion. Power cylinder of press is stationary secured to said rear cross piece. Main traverse bar and plunger secured to it are joined with additional cylinder supporting said short extrusion ram. Hollow long extrusion ram is mounted on front cross piece coaxially relative to said short ram. In cavity of said short ram needle with needle holder are arranged. Press is also provided with flanged broach. EFFECT: enhanced efficiency of method, improved design of press. 25 cl, 8 dwg

Description

 The invention relates to the field of metal forming, and in particular to a method for hot extrusion of hollow products with the active action of friction and a hydraulic press for its implementation, and can be used to obtain hollow products that are widely used in aircraft, chemical engineering, shipbuilding, etc. d.

 Conventional method for hot extrusion of hollow bodies (see prospectus from Strang- und Rohrpressanlagen, SMS Schloemannsiemag Aktiengesellschaft, Düsseldorf und Hilchenbach. 1000/12/81. Printed in the Federal Republic of Germany by Servicedruck Kleinherne KG Düsseldorf: heating the hollow billet in the furnace, feeding it into the container, passing the needle through the cavity of the billet, and squeezing the billet with a press stamp through the annular gap formed by the matrix channel and the needle, with the simultaneous movement of the stamp, needle and container. cooling, and avshiysya press residue is separated from the matrix and placed in the waste. This method is the inverse to the movable needle.

 With this method, there is no need to overcome the frictional forces between the container and the workpiece, and between the needle and part of the workpiece in the area from the press washer to the crimp zone, therefore, the implementation of the reverse method requires significantly less energy costs.

 However, when extruding products in the absence of friction, the surface layers of the workpiece are not updated. The surface quality of such a product depends on the state of the surface of the original workpiece.

 The resulting products have no internal defects, but extrusion requires blanks with machined inner and outer surfaces, which requires additional costs.

 However, for the above-described extrusion method, in view of the presence of a significant gradient of velocities in the compressing part of the plastic zone, a non-uniform distribution of the structure and physicomechanical properties along the length and cross section of the articles is characteristic.

 In addition, the surface quality of the products is deteriorated due to the elimination of the action of shear deformations and the occurrence of significant tensile stresses on the surface of the products, which can lead to cracking.

 A press is known for implementing the above method (see prospectus of the company SMS Hasenclever. Fachbericht Strang- und Rohrpressen. Aufbau und Arbeitsweise einer neuen Indirekt Strang- und Rohrpresslinie fur Aluminum. Sonderdrbck aus Aluminum 60 (1984) 6, s. 424/430. SMS Hasenclever Maschinenfabrik GmbH. Witzelstrasse 55. Postfach 5529 D-4000 Düsseldorf 1), which contains a container mounted on the bed, having the possibility of reciprocating movement along its longitudinal axis, and a crosshead with a hollow plunger of the main power cylinder fixedly mounted on it on the rear cross member. Inside the plunger of the main power cylinder there is a cylinder with a plunger of the power drive for moving the needle. On the rear cross member there are two container moving cylinders, the plungers of which are rigidly fixed to the container. A hollow baler is firmly fixed to the traverse, making contact with the container and locking the container during extrusion. On the other side of the container, a hollow long press stamp is fixed coaxially with it, fixedly mounted on the front crosshead. The internal cavities of the hydraulic power cylinders are connected through a junction box to the high and low pressure lines.

 The heated billet is captured with a tick feed device and lifted onto the axis of the press. Idling the container towards the feeder, the workpiece is partially pushed into the container. Next, the needle is passed into the cavity of the workpiece, and then remove the feed device to its original position.

 The final supply of the workpiece into the cavity of the container sleeve is carried out by moving the container. Then, a die is fed onto the hollow die and the extrusion process is started in the reverse way.

 The return cylinders for moving the container are opened, and the high pressure liquid is supplied to the main and power cylinders of the needle. Under the influence of the press stamp (stopper), the workpiece is squeezed out through the gap between the die channel and the needle. At this moment, the speeds of the pressing beam, container and needle are equal, because the cork moves the container at the same time, and the needle, under the constant influence of high-pressure fluid on the plunger of the needle cylinder, is in its frontmost position and therefore moves with the speed of the pressing beam. After reaching the specified value of the press residue, the process is stopped. The press residue is removed from the container by the cylinders for moving the container and separated. Products are removed and the cycle repeats.

 The above method does not allow to obtain hollow products with high quality internal and external surfaces, and the design of the press does not allow the extrusion of metal with the active action of friction. Therefore, the products are obtained with the worst quality of the internal and external surfaces of the hollow products, a reduced level of mechanical properties compared to the direct method. Significant in magnitude of the velocity of the outflow of metal in comparison with the same direct method cannot be achieved on this installation.

 There is another method for hot extrusion of hollow products, which improves the quality of the inner surface of hollow products through the use of a free-floating (loose) needle (see, for example, Laue K. Zeitschrift für Metallkunde, 1959, N. 9, s. 495).

 In contrast to the reverse method with a movable needle, in this method the needle is not fixed and has the possibility of free axial movement in the direction of the outflow of metal.

During the extrusion of hollow products, depending on the ratio of the friction forces acting on the needle, at the initial stage it moves with the speed of the press stamp. In this case, the surface of the workpiece within the compressing part of the plastic zone (. Figure 1 border area indicated by the line CC) having friction force resisting action τ _t, and on the needle surfaces within the crimping zone - active action of friction forces τ _a. Under the influence of all these forces, the needle tends to move towards the outflow of the metal, but at the initial stage of the process these forces are insufficient due to the large contact surface, so the needle moves with the speed of the stamp. As the contact surface of the workpiece decreases during extrusion, the needle gradually begins to outpace the stamp, inducing friction forces τ _am on the surface of the workpiece from the stamp to the crimp zone (CC). In this case, the needle speed gradually increases and tends to the rate of metal outflow, which leads to the intensification and localization of shear deformation, and as a result to increased structural inhomogeneity, expressed as a large-crystalline rim. The use of loose needles can significantly improve the quality of the inner surface of the hollow products on a limited part of their length mainly at the final stage of the process. Thus, most of the hollow product is obtained with an inner surface quality identical to the reverse method.

 There is another method for hot extrusion of hollow products with the active action of friction forces (see SU N 504574, class B 21 C 23/08, 1976, p.2), which includes heating a hollow billet to be extruded, placing in the sleeve of the container into which a needle is passed through the cavity of this preform, squeezing the preform with a short press stamp through the annular gap formed by the matrix channel and the needle, which determines the shape and geometric dimensions of the finished product, during extrusion, the ratio of the speed of movement of the stamp, container Nera and needles support in a certain interval.

The friction forces of the active action τ _ac , are induced on the outer surface of the workpiece from the container throughout the entire process, and on the inner surface of the workpiece, the same forces τ _am arise after pressing a certain part of the workpiece when the conditions for exceeding the speed of the needle over the speed of the stamp are satisfied. Such kinematic conditions make it possible to somewhat equalize the flow rates of the metal in the gap between the matrix and the needle, which makes it possible to obtain better products.

 It was experimentally established that the effectiveness of this process depends on the conditions of interaction of the container and the needle with the workpiece. Therefore, during extrusion, when the speeds of the container and the needle significantly exceed the speed of the short press stamp, an excessive shift of the contact layers of the workpiece is observed. This circumstance causes an intensive flow of the near-contact layers of the billet towards the matrix, which leads to a decrease in the permissible extrusion rate, to structural heterogeneity and to a deterioration in the quality of hollow products, for example, pipes. In addition, the choice of a large ratio of the speed of movement of the container and the needle to the speed of movement of the press stamp requires a reduction in the initial length of the workpiece, which leads to a decrease in the productivity of the press, or an increase in the length of the container and the needle, which complicates the design of the press, its cost and the resistance of the needles .

 A known press for the extrusion of hollow products (pipes) using the active action of friction forces (see "News of higher educational institutions" N 11, Ferrous metallurgy, 1972, S. 107 - 109).

 A hydraulic extrusion press for producing hollow products contains upper and lower crossbars rigidly mounted on the bed, a container mounted with the possibility of reciprocating movement along the longitudinal axis of the press, a main movable crosshead with a plunger rigidly fixed to it, at least one ram, housing which is fixedly mounted on the upper cross member, and the inner cavity is connected with high and low pressure lines, an additional cylinder connected to the main movable a reverse, and the internal cavity of which is connected via a throttling device to the low-pressure line, a short stamp is fixed on the plunger of the additional cylinder, and a hollow long press is fixed on the lower cross member coaxially with the short press stamp. The specified press can be performed both in horizontal and vertical versions, which does not change the essence of its work. The figure shows the vertical source.

 In the initial position, the plunger of the additional cylinder is extended as far as possible from the cylinder, and the needle is retracted to the extreme position by means of a spring.

The heated hollow billet is fed to the axis of the press and is pushed into the container using a hollow long press stamp with a matrix. The needle is then passed through the cavity of the workpiece. High pressure fluid is fed into the master cylinder and the crosshead together with the container is lowered down. Extruding begins. At this moment, the speeds of the container, needle and stamp are the same. There is a process of pressing in the reverse way. After the outflow of metal begins, the throttle is opened and the liquid from the additional cylinder begins to flow into the low-pressure line. The plunger of the additional cylinder is heated, which ensures the displacement of the container relative to the workpiece. The friction forces of the active action τ _ac are induced on the side surface of the workpiece. When extruding pipes according to this scheme, depending on the stage of the process, the speed of movement of the needle relative to the workpiece changes.

 This press allows the extrusion process to be carried out using the bilateral active action of the friction forces.

 At the same time, in order to achieve high performance of the press, to obtain high quality of the inner surface of the hollow products and to ensure a high level of physical and mechanical properties of the products, it is necessary to maintain the optimum ratio of the speed of movement of the container and the stamp during extrusion. This press does not allow you to accurately maintain this ratio. The regulation of the speed of movement of the container relative to the stamp is carried out by releasing the liquid from the additional cylinder through the throttle to the low pressure line.

 On this press, during the extrusion process, it is necessary to open and close the throttle. If the ratio of the speeds of movement of the container and the press stamp is deviated from the optimum, hollow articles with defects can be obtained (cracks, uneven distribution of structure and physical and mechanical properties along the length of the products).

 The nature of the change in the speed of movement of the loose needle placed inside the cavity of the short press stamp does not allow the frictional forces of the active action to be induced on the inner surface of the hollow product, therefore, the quality of the inner surface is low and nothing at all on the part of the hollow product pressed under these conditions differs from the method of extruding hollow articles with a movable needle, when the speeds of the needle and the short stamp are equal. However, the final stage of the process is characterized by the formation of an increased quality of the inner surface of the hollow products in comparison with the initial stage. A sharp increase in the speed of the needle and its gradual approach to the rate of metal outflow leads to the localization of shear deformation at the final stage and, as a result, to structural heterogeneity in the back of the hollow product.

 The present invention is the creation of such a method of hot extrusion of hollow products with the active action of friction forces and a hydraulic extrusion press for its implementation, which would be due to the optimal ratio of the speeds of movement of the container, the stamp and the needle would significantly increase the productivity of the process of obtaining hollow products while increasing their physical and mechanical properties, the quality of the inner surface and the accuracy of the geometry.

 This problem is solved due to the fact that in the method of hot extrusion of hollow articles with the active action of friction forces, the hollow preform to be extruded is heated, placed in the container sleeve, in which a needle is passed through the cavity of this preform, and the preform is extruded using a short stamp through the formed the matrix channel and the needle annular gap, which determines the shape and geometric dimensions of the finished product, in the process of extrusion, the ratio of the speeds of movement of the stamp, container and needle kept in a certain interval, and according to the invention during the extrusion process, the speed of movement of the container and the speed of movement of the needle exceed the speed of movement of the short press stamp.

 During the extrusion process, the speed of movement of the container exceeds the speed of movement of the short press stamp 1.01-1.4 times, and the speed of movement of the needle exceeds the speed of movement of the short stamp 1.01-1.05 times. At the same time, the speed of movement of the container exceeds the speed of movement of the needle by 1.02-1.33 times, depending on the coefficient of drawing and the temperature gradient.

 This allows you to increase the productivity of the process compared to all known methods, to improve the quality of the external and internal surfaces of the hollow products and the level of their mechanical properties and to ensure the receipt of products with a given distribution of physical and mechanical properties along the length and cross section of the hollow product.

 During the extrusion process, the ratios of the speed of movement of the container and the speed of movement of the short press stamp, the speed of movement of the needle and the speed of movement of the short press stamp are changed. This makes it possible to control the volumetric effect of the active action of the friction forces throughout all stages of the process, maintaining quasi-established conditions for the flow of the deformable material, which in turn makes it possible to increase the uniform distribution of the physicomechanical properties of the product material along their length.

 In the process of extrusion, the ratio of the speed of movement of the container and the speed of movement of the short stamp is reduced from 1.4 to 1.01 depending on the drawing ratio of the hollow product.

 This makes it possible to obtain hollow products with a given distribution of mechanical properties along the length of the finished product.

 During the extrusion process, the ratio of the speed of the needle to the speed of the short press can be reduced from 1.05 to 1.01.

 This makes it possible to improve the quality of the inner surface of the hollow product along the entire length of the product in connection with a decrease in the degree of slipping of the needle relative to the workpiece.

 During the extrusion process, the speed of movement of the short stamp can be changed depending on the distribution of the temperature gradient along the length of the workpiece.

 This makes it possible to even out the distribution of physicomechanical properties along the length of hollow products.

 In this case, it is rational to heat the front end of the workpiece in the temperature range from 0.75 to 0.9 of the temperature of the upper boundary of the range of technological plasticity of the extrudable material, and to heat the rear end of the workpiece in the temperature range from 0.6 to 0.7 of the temperature of the upper boundary of the technological plasticity range extrudable material depending on the wall thickness of the extrudable workpiece.

 It also allows an additional approximately 20% increase in the productivity of the process and to even out the distribution of physical and mechanical properties along the length of the products.

 Before extrusion, the heating temperature of the container is set in the range from 1 to 0.95, the heating temperature of the front end of the workpiece.

 This allows you to further increase the degree of realization of the active action of the friction forces, reduce the slippage of the sleeve relative to the workpiece, and also eliminate the cooling of the rear end of the workpiece resulting from its interaction with a short stamp.

 During the extrusion process, the needle is informed of a cyclic translational movement in the direction of metal flow due to cyclic loading.

 This eliminates the sticking of the extrudable material to the needle, which increases the resistance of the needle, as well as the quality of the inner surface of the hollow product.

 This problem is also solved due to the fact that the hydraulic extrusion press for producing hollow products contains front and rear cross members rigidly mounted on the bed, a container mounted with the possibility of reciprocating movement along the longitudinal axis of the press, the main movable crosshead with a plunger fixed to it, at least one power cylinder, the casing of which is fixedly mounted on the rear cross member, and the internal cavity is connected to the high and low pressure lines, a cylinder connected to the main movable traverse, and the inner cavity of which is connected via a throttling device to the low pressure line, a short press stamp fixed to the plunger of the additional cylinder, and a hollow long press stamp fixed to the front cross member coaxially with the short press stamp , and also according to the invention, the short press stamp is hollow and integral with the press washer, a needle is installed in its cavity with a needle holder connected to the plunger of the needle power cylinder and its movable the traverse placed inside the main movable traverse, the press is equipped with a piercing with a flange, a cylindrical sleeve with collars made respectively on its inner and outer surfaces, and a spring-loaded element placed between the body of the short press stamp and the outer surface of the cylindrical sleeve, while the piercing with the flange is installed inside the short press stamp and is rigidly connected to the cylindrical sleeve, and the needle is placed inside the piercing and is made with a cylindrical collar, the outer diameter of which corresponds to the inner diameter of the cylindrical sleeve, and is rigidly connected to the needle holder by means of a shank.

 This ensures the automatic execution of the specified kinematic modes of operation of the press during the extrusion process and eliminates the leakage of metal between the needle and the stamp.

 The plunger of the additional cylinder is installed inside the main movable crosshead, made hollow and provided with a centering shank passing through the bottom of the cylindrical body of the additional cylinder.

 This allows you to get the necessary ratio of the speeds of movement of the container and the short press stamp, improve alignment and simplify the design.

 The main throttling device of the additional cylinder contains at least one stabilizing cylinder, which is a cylindrical body, in the inner cavity of which a plunger is located, and one of these elements of the stabilizing cylinder is mounted on the rear cross member, and the other is rigidly connected to the main movable traverse, and the internal cavity the stabilizing cylinder communicates hydraulically with the internal cavity of the additional cylinder.

 This ensures that the optimal ratio of the speed of movement of the container and the speed of movement of the short press stamp during the extrusion process is automatically obtained.

For a given constant value of the ratio of the speed of movement of the container and the speed of movement of the short press stamp, the cross-sectional area F _{2 of the} stabilizing cylinder may be equal to
F ₂ = F ₁ (1 - 1 / K _v1 ),
Where
F ₁ - the cross-sectional area of the additional cylinder;
F ₂ is the cross-sectional area of the stabilizing cylinder;
K _v1 is the ratio V _c / V _{r of the} speed V _{c of} movement of the container and the speed V _{r of} movement of the short stamp.

The length H _{1 of the} working cavity of the additional cylinder is
H ₁ = H _p (1 - 1 / K _v1 ,
Where
H ₁ - the length of the working cavity of the additional cylinder;
H _p - the maximum length of the stroke of the stabilization cylinder.

 This allows you to get the necessary ratio of the speed of movement of the container and the speed of movement of a short stamp.

 It is advisable for a constant ratio of the speed of movement of the container and the speed of movement of the short press stamp to determine the maximum value of this ratio based on the total cross-sectional areas of all pairs of cylinders that stabilize the speed of movement of the short press stamp.

 This provides the necessary ratio of the speed of movement of the container and the speed of movement of the short press stamp.

 A hydraulic extrusion press may contain at least two forcing-return cylinders, each of which is made in the form of a cylindrical body, in the inner cavity of which a plunger is located, and one of these elements of each forcing-return cylinder is fixedly mounted on one of the crossbars, and the other is rigidly connected to the main movable traverse, and the inner cavity of each of them communicates with the highway fluid low and high pressure, and the inner cavity of each force-return force th cylinder is hydraulically connected to the inner space of the auxiliary cylinder.

 This allows you to significantly save high-pressure fluid and return the main movable crosshead to its original position.

 The hydraulic press may contain one pair of needle return cylinders, consisting of a cylindrical body and a plunger, one of the elements of each of which is fixed to the main and the other to the movable needle traverse.

 This allows you to control the speed of the needle according to a given kinematic law.

 In addition, the press may contain an intermediate movable crosshead rigidly connected to the plunger of the additional cylinder, and intermediate cylinders, each of which consists of a cylindrical body and a plunger, in turn, the housing of each of which is placed on the main movable crosshead, and the plunger is rigidly connected to the intermediate movable traverse.

 This makes it possible to stabilize the speed of retraction of the needle back and expand the technological capabilities of the press.

 The cylinders for stabilizing the movement of the needle are force-returning power cylinders, consisting of a cylindrical body and a plunger, one of the elements of each of which is rigidly connected to the rear cross member, and the other is also rigidly connected to the main movable traverse.

 This allows us to simplify the design of the press and make it compact, as well as expand the range of variation of the kinematic coefficient.

 The inner cavity of the intermediate cylinder communicates with the inner cavity of the return cylinder of the needle, and the inner cavity of the power cylinder of the needle is hydraulically connected to the inner cavity of the force-return cylinder.

 This simplifies press management.

 In addition, the internal cavities of the return cylinders of the needle and the force cylinder of the needle are hydraulically connected through the corresponding valves to the high and low pressure lines.

 This saves high pressure fluid and simplifies press control.

 The line connecting the internal cavities of each stabilization cylinder and forcing-return cylinders hydraulically connected to the internal cavity of the additional cylinder, in addition, communicates with the high and low pressure lines through the corresponding valves.

 This simplifies press management.

 A hydraulic extrusion press may include at least one additional throttling device having a housing with inlet and outlet openings provided with at least one cover, and a spool spring with two through cavities spring-loaded from the side of this cover is installed inside this device, the configuration and geometric dimensions of each of which determine the magnitude of the speed of mutual movement of the container and the short press stamp, as well as the needle and the short press stamp, with one through The cavity is hydraulically connected through the corresponding openings to the internal cavity of the additional cylinder and the low pressure line, and the other through cavity, through other corresponding openings, is hydraulically connected to the internal cavity of the needle power cylinder and also to the low pressure line.

 This allows you to get variable ratios of the speeds of movement of the container, the short press stamp and the needle during the process.

 In addition, the spool of the additional throttling device has a window of variable cross section, inside of which jumpers are installed.

 This provides a pulsating translational movement of the needle and reduces the adhesion of the pressed metal to the needle.

 The press may contain at least one valve installed in the line connecting the internal cavity of the additional cylinder with an additional throttling device.

 This makes it possible to expand the technological capabilities of the press and simplify the management of the press.

 In addition, the press may contain at least one valve installed in the line connecting the inner cavity of the needle cylinder with an additional throttling device.

 This makes it possible to obtain variable values of the ratio of the speeds of movement of the needle and the short press stamp.

 In FIG. 1 schematically shows the effect of friction forces during the extrusion of hollow products according to the proposed method; in FIG. 2 is a flowchart illustrating the proposed method, FIG. 3 - hydraulic extrusion press for implementing the proposed method; in FIG. 4 - tool block of the proposed hydraulic press; in FIG. 5 is one embodiment of a hydraulic extrusion press according to the invention; in FIG. 6 - additional throttling device of the proposed hydraulic press; in FIG. 7a, b, c show the shape of the channels in the spool cavity of an additional throttling device according to the invention; in FIG. 8 is an embodiment of a hydraulic extrusion press with power stabilizing needle cylinders according to the invention.

In FIG. 1 - 8 the following notation is introduced:
1 - hollow billet, 2 - container sleeve, 3 - container, 4 - needle, 5 - die, 6 - short stamp, 7 - long stamp, 8 - piercing, 9 - bed, 10 - front cross member, 11 - the rear cross member, 12 - the column, 13 - the main movable crosshead, 14 - the plunger of the power cylinder for direct movement of the container, 15 - the plunger of the power cylinder of the reverse movement of the container, 16 - the cylindrical body of the power cylinder of the direct movement of the container, 17 - the cylindrical body of the power cylinder of the reverse movement container, 18 - window in the front popper rank, 19 - the cylindrical body of the main power cylinder, 20 - the plunger of the main power cylinder and at the same time the cylindrical body of the power cylinder for moving the needle, 21 - the cylinder body for the reverse movement of the beam, 22 - the plunger of the cylinder for the reverse movement of the beam, 23 - the cylindrical body of the stabilizing cylinder, 24 - plunger of the stabilizing cylinder, 25 - axial channels inside the plunger 24 of the stabilizing cylinder, 26 - pipeline, 27 - the internal cavity of the stabilizing cylinder, 28 - the internal cavity of the additional cylinder a, 29 - the body of the additional cylinder, 30 - the plunger of the additional cylinder, 31 - the centering shank of the plunger 30 of the additional cylinder, 32 - pushers, 33 - the press washer, 34 - the inner cavity of the power cylinder moving the needle, 35 - the plunger of the power cylinder moving the needle, 36 - needle holder, 37 - movable needle traverse, 38 - body of the return cylinder for moving the needle, 39 - plunger of the return cylinder for moving the needle, 40 - internal cavity of the main power cylinder, 41 - pipeline of the high pressure line, 42 - filling valve, 43 - p speed booster, 44 - inner cavity of the return cylinder for moving the needle, 45 - inner cavity of the cylinder for returning the movable beam, 46 - switchgear, 47 - low-pressure line, 48 - valve, 49 - valve, 50 - valve, 51 - valve, 52 - valve, 53 - pipeline, 54 - additional throttling device, 55 - pipeline, 56 - valve, 57 - valve, 58 - controlled valve, 59 - additional pipeline, 60 - valve, 61 - regulator, 62 - controlled valve, 63 - uncontrolled valve, 64 - pipeline, 65 - the internal cavity of the reverse cylinder container premises, 66 - internal cavity for direct movement of the container, 67 - pipeline, 68 - valve, 69 - pipeline, 70 - cylindrical groove, 71 - piercing flange, 72 - cylindrical sleeve, 73 - inner sleeve shoulder 72, 74 - external sleeve shoulder 72, 75 - spring-loaded element, 76 - groove, 77 - cylindrical shoulder of the needle 4, 78 - shank of the needle 4, 79 - needle holder, 80 - insert of the press washer, 81 - mechanism for feeding the workpiece, 82 - mechanism for removing and feeding the matrix, 83 - body of the forcing-return cylinder, 84 - stepped plunger of the forcing-return cylinder, 85 - inside the front cavity of the forcing-return cylinder, 86 — axial channels inside the plunger 84 of the forcing-return cylinder, 87 — pipeline, 88 — valve, 89 — pipeline, 90 — valve, 91 — valve, 92 — valve, 93 — high-pressure pipeline, 94 - case, 95 - inlet, 96 - inlet, 97 - outlet, 98 - outlet, 99 - spool, 100 - spool cavity, 101 - spool cavity, 102- spring element, 103 - power cylinder housing moving the spool 97, 104 - plunger of the power cylinder for moving the spool 97, 105 - pipeline, 106 - t ruboprovod, 107 - the inner cavity of the slide cylinder 97, 108 - the cover, 109 - jumpers, 110 - the spindle, 111 - the intermediate movable crosshead, 112 - the housing of the intermediate cylinder, 113 - the plunger of the intermediate cylinder, 114 - the inner cavity of the intermediate cylinder, 115 - valve, 116 - pipeline, 117 - pipeline, 118 - pipeline, 119 - valve.

 The proposed method for hot extrusion of hollow products with the active action of friction forces is as follows.

 The hollow billet 1 (Fig. 1, 2) to be extruded is heated. The heating of the hollow preform 1 can be carried out, for example, in induction furnaces, resistance furnaces, and gas flame furnaces (not shown in FIG. 2). The heating temperature range of the preform 1 is selected depending on the type of alloy of the preform 1 to be extruded.

For example, in the case of heating a preform 1 of hardly deformable aluminum alloys, the heating is carried out to a temperature of about 300 - 450 ^o C depending on the selected press force, the requirements for the physicomechanical properties of the products and the speed of extrusion.

 Heating the workpiece 1 before extrusion allows to reduce the resistance to deformation of the material of the workpiece, which reduces the energy consumption for the completion of the extrusion process. In addition, in a number of difficult-to-deform alloys exhibiting a press effect (structural hardening effect), in the case of processing these alloys by pressure using heating billets, the level of mechanical properties of the products increases. In addition to this, heating in some cases allows increasing the adhesive interaction of the workpiece 1 with the sleeve 2 of the container 3 and the needle 4, which leads to an increase in the friction forces, and this is very important for the proposed process, since in the considered method the friction forces between the sleeve 2 of the container 3, the needle 4 and workpiece 1 play a positive role by increasing the speed of the peripheral metal flow along the wall thickness of the hollow workpiece near the sleeve of the container 2 and the needle 4. Thus, their growth to a certain value helps to level the flow rates of the meta in the cross section of the workpiece near the gap between the channel of the matrix 5 and the needle 4. This allows you to increase the limiting velocity of the flow of metal. After heating, the preform 1 is fed to the press (Fig. 2, a), the needle 4 is passed through it, and then pushed into the cavity 2 of the sleeve of the container 3 of the press (Fig. 2, b). The length of the container 3 is selected in such a way that the whole blank 1, die 5 and short press stamp 6 can freely fit in it (Fig. 2, c, d). The length of the short stamp 6 is adopted taking into account the kinematics of the movement of the container 3 and the stamp 6.

To reduce the energy costs of the extrusion process before deformation, the container 3, the matrix 5 and the short press stamp 6, it is advisable to pre-heat. The heating temperature depends on the material of the extrudable billet 1. For example, when extruding difficult to deform aluminum alloys, it is approximately 300 - 400 ^o C.

Then begin to move the container 3, the needle 4 and the short press stamp 6 at the same time towards the matrix 5 mounted on the long press stamp 7, and the speeds of the container 3 and the needle 4 are greater than the speeds of the short press stamp 6 and piercing 8. After the short the press stamp 6, the hollow blank 1 and the die 5 are in contact, the unpressing of the blank 1 begins (Fig. 2, e). At this stage, the workpiece 1 occupies the entire bounding volume. The outer diameter of the workpiece 1 becomes equal to the inner diameter of the sleeve 2 of the container 3, and the inner diameter equal to the diameter of the needle 4. Then the metal begins to extrude into the gap between the channel of the matrix 5 and the needle 4. The configuration of the gap corresponds to the cross section of the resulting hollow product, but taking into account the thermal expansion of the matrix 5 and needles 4 as a result of their heating and some shrinkage of the metal after its cooling. At the stage of pressing the workpiece 1, the speed V _{c of the} movement of the container 3, the speed V _{m of the} movement of the needle 4 and the speed V _{r of the} movement of the short stamp 6 can be equal (in this case, the so-called reverse extrusion method is implemented).

After the beginning of the extrusion, the movement speed V _{c of the} movement of the container 3 and the speed V _{m of the} movement of the needle 4 are increased compared to the speed V _{r of the} movement of the short press stamp 6. The ratio V _c / V _{r of the} speed V _{c of the} movement of the container 3 to the speed V _{r of the} movement of the short press the stamp 6 is called the kinematic coefficient of the container K _v1 , and the ratio V _m / V _{r of the} speed V _{m of the} movement of the needle 4 to the speed V _{r of the} movement of the short press stamp 6 is called the kinematic coefficient of the needle K _v2 .

As a result of such mutual displacements, friction forces τ _ac appear on the side surface of the workpiece 1, which are directed toward the outflow of metal, which makes it possible to increase the velocity of the peripheral metal flow in the workpiece 1 and slow down the speed of the intermediate layer located between the sleeve 2 and the needle 4. Advance of the needle 4 of the short the stamp 6 increases the speed of the metal flow near the needle 4. This significantly changes the nature of the metal flow, which leads to a smoothing of the metal flow in the crimping part of the plastic zone W, and consequently flax and in the gap between the channel die 4 and needle 3 that affects an increase in metal outflow velocities and alignment structure.

It was experimentally established that in the case of extrusion, when the ratio V _m / V _{r is} more than 1, then compressive stresses τ _am are created on the inner cavity of the workpiece 1 in the direction from the short press stamp 6 to the boundary of the crimping zone CC, which favorably affects the quality of the inner surface , because under such conditions, the residual cast structure is removed near the contact surface of the workpiece 1. It also helps to reduce the surface roughness of the finished product.

A more uniform metal flow provides a decrease in tensile stresses τ _t on the inner and outer surfaces of the finished products. These stresses are the main limiting factor in the choice of the limiting rate of metal outflow for a number of difficultly deformed alloys, primarily aluminum. Thus, the reduction of tensile stresses on the workpiece τ _t near the needle and the matrix τ _td allows to increase the maximum permissible extrusion rates during extrusion of difficult to deform aluminum alloys by at least 10 - 40% compared with all known methods. In addition, such a favorable metal flow creates conditions that can increase the dispersion of the structure of the front end of the product and thereby reduce the uneven distribution of mechanical properties along the length and cross section of the products.

 Given that during the extrusion process under the conditions of the active action of friction forces, the material of the workpiece 1 experiences a slowdown of the intermediate metal flow adjacent to the needle 4 in the direction from the press stamp 6 to the crimp zone CC, and this contributes to an increase in the degree of dispersion of the structure and an increase in the dislocation density in the crystalline lattice of pressed metal, which increases the overall level of mechanical properties of hollow products. For example, when extruding hard-deformed aluminum alloys, ceteris paribus, the increase in the mechanical properties of hollow products is from about 10 to 25%.

 At the same time, the effectiveness of this process substantially depends on the interaction conditions of the sleeve 2 of the container 3 and the needle 4 with the workpiece 1, i.e., on the magnitude of the degree of realization of the active action of the friction forces.

 The predetermined geometry of the hollow articles is ensured by the conditions of centering of the needle 4, matrix 5 and container 3 mounted on the guides of the frame 9 between the front 10 and rear 11 cross members connected by four columns 12 (Fig. 3).

It was experimentally established that in the case of extrusion, when the ratio V _c / V _{r of the} speed V _{c of the} movement of the container 3 to the speed V _{r of the} movement of the press stamp 6 and the ratio V _m / V _{r of the} speed of movement V _{m of the} needle 4 to the speed V _{r of} the short press -stamps 6 exceed the maximum permissible values, there is an excessive shift of the sleeve 2 of the container 3 and the needle 4 relative to the workpiece 1. This circumstance causes an accelerated flow of metal near the surfaces of the sleeve 2 of the container 3 and the needle 4, which, in turn, leads to localization of the shear deformation and increased structural heterogeneity. This requires a reduction in extrusion speed.

Thus, the shift of the contact layers of metal near the sleeve 2 of the container 3 and the needle 4 should be strictly regulated. The extrusion process is carried out to a certain value of the press residue (Fig. 2, f), the height of which is mainly determined by the moment the formation of the press weights of the first kind begins, and depends on the direction of the stress τ _tr at the end of the workpiece.

 After the extrusion is finished, the finished product is separated from the press residue (Fig. 2, g), for example, by pressing needle 4 by piercing the pressostat 8. Press needle 4 together with the piercing from matrix 5 to the initial position before the piercing (Fig. 2, h), and then the main movable beam is diverted to a distance sufficient to enter the matrix removal mechanism (Fig. 2, g) with a press residue.

 Then, by moving the container 3 forward until it is pressed against the front cross member 10, the matrix 5 is pressed out with a press residue (Fig. 2, i). After that, a mechanism for removing the matrix 5 with a press remainder is fed to the axis of the press, which clamps the matrix 5 on the removal mechanism. Next, the main movable traverse 13 with the needle 4 is returned to its initial position (Fig. 2, j).

 Then, after the removal of the mechanism for removing the matrix 5 to its original position (Fig. 2, k), the press residue is separated from the matrix outside the press.

During the extrusion process, the container 3 can be moved at a speed V _c exceeding the speed V _{r of the} press stamp 6 1.03-1.4 times. It was experimentally established that in the case of extrusion, when the ratio V _c / V _{r of the} speed V _{c of the} movement of the container 3 and the speed V _{r of the} movement of the stamp 6 exceeds 1.4, an excessive shift of the container 3 relative to the workpiece 1 is observed. This circumstance causes an accelerated flow of peripheral layers of metal, which, in turn, leads to the localization of shear deformation, and, as a consequence of this, to a large structural heterogeneity. This leads to the need to reduce the speed of extrusion.

In addition, the choice of an excessively large ratio V _c / V _{r of the} speed V _{c of the} movement of the container 3 to the speed V _{r of the} movement of the short stamp 6 (more than 1.4) requires either a reduction in the initial length of the workpiece 1, which leads to a decrease in the productivity of the press, or increasing the length of the container 3, which increases the metal consumption of the press structure and its cost.

The use in the extrusion process of an excessively low ratio V _c / V _{r of} speed V _c , movement of the container 3 and speed V _{r of the} movement of the short press stamp 6 (below 1.01) leads to the localization of shear deformation only in the boundary layer of the workpiece 1, which reduces the volumetric the effect of friction. This leads to uneven flow of the metal and reduces the permissible level of extrusion speed, which leads to a deterioration in the quality of hollow products.

During the extrusion process, the needle 4 can be moved with a constant ratio V _m / V _{r of the} speed V _{m of the} movement of the needle 4 to the speed V _{r of the} movement of the press stamp 6, which is in the range from 1.01 to 1.05.

It was experimentally established that in the case of extrusion, when the ratio V _m / V _{r of the} speed V _{m of the} movement of the needle 4 and the speed V _{r of the} movement of the press stamp 6 exceeds 1.05, an excessive shift of the needle 4 relative to the workpiece 1 is observed. This circumstance causes an accelerated flow of the layers metal adjacent to the needle 6, which, in turn, leads to an increase in uneven flow. This forces a decrease in the speed of extrusion. The use of the ratio V _m / V _{r of the} speed V _{m of} the needle 4 and the speed V _{r of the} movement of the short press stamp 6 below 1.01 during extrusion leads to the localization of shear deformation only in the thin boundary layer of the workpiece 1, which reduces the volumetric effect of the friction forces and does not create sufficient compressive stresses on the inner surface of the workpiece, sufficient to eliminate contact defects.

During the extrusion process, the container 3 can be moved with a constant ratio V _c / V _{m of} speed V _{c of} movement of the container 3 to the speed V _{m of} movement of the needle 4, which is in the range from 1.02 to 1.33.

The level of the mechanical properties of the hollow products and their distribution along the length are affected by the initial temperature of the workpiece 1, the extrusion rate and the ratio V _c / V _{m of the} speed V _{c of the} movement of the container 3 and the speed V _{m of the} movement of the needle 4.

The leading movement of the container 3 relative to the needle 4 allows you to equalize the velocity gradient of the metal near the channel of the matrix 5, to increase the dispersion of the structure, the density of the dislocations of the crystal lattice of the metal and improve the level of mechanical properties of hollow products. Keeping constant the ratio V _c / V _{m of the} speed V _{c of the} movement of the container 3 and the speed V _{m of the} movement of the stamp 6 and the ratio V _m / V _{r of the} speed V _{m of the} movement of the needle 4 and the speed V _{r of the} movement of the short stamp 6 provides an even distribution of mechanical properties of the metal along the length of the products with the formation of a structure uniform in wall thickness.

As a result of numerous experiments, it was found that in the case where the ratio V _c / V _{m of the} speed V _{c of the} movement of the container 3 and the speed V _{m of the} movement of the needle 4 is higher than 1.33, the peripheral layers of the workpiece 1 undergo intensive shear deformation, which is accompanied by dynamic recrystallization. This leads to a decrease in the resistance to deformation of the extrudable metal in these layers, because the dislocation density in the structure of the crystal lattice decreases sharply, and the grain size increases several times, which leads to a decrease in the level of mechanical properties of the products.

The use of the ratio V _c / V _{m of the} speed V _{c of the} movement of the container 3 and the speed V _{m of the} movement of the needle 4 of less than 1.02 during extrusion leads to slight shear deformation in the thin boundary layer of the workpiece 1 and limits the effect on the central layers of the workpiece 1. The structure of these layers remains coarse-grained, and products have a reduced level of mechanical properties.

During the extrusion process, the ratios V _c / V _r , V _m / V _r can be changed.

 During deformation of the workpiece 1, taking into account its preliminary uniform heating, intense generation of deformation heat occurs, which leads to a decrease in the resistance of the metal to deformation and to an increase in the adhesion of the metal of the workpiece 1 to the metal of the sleeve 2 and the needle 4. This leads to additional shear deformations increasing along the length of the product. Under such conditions, the level of properties at the rear of the product is significantly higher than the level of the front.

The implementation of the variable ratios V _c / V _r and V _m / V _r allows you to control the effect of the release of deformation heat and to equalize the distribution of physical and mechanical properties along the length of the products. As a result of this, it is possible to further increase the productivity of the process as a whole compared with all known extrusion methods by a minimum of m. During the extrusion of the workpiece 1, the ratio V _c / V _{r of the} speed of movement of the container 3 and the speed V _{r of the} movement of the short press stamp 6 can be gradually reduced from 1.15-1.4 to 1.01-1.02 depending on the drawing ratio hollow products.

When extruding as a result of the work of deformation, the workpiece 1 generates heat depending on the degree of deformation, indirectly expressed through the coefficient λ _{m of the} hood. So, the higher the extraction coefficient λ _m , the greater the ratio V _c / V _{r of the} speed of movement of the container 3 and the speed V _{r of the} movement of the short press stamp 6, it is necessary to start the process (maximum 1.4) and gradually reduce it to the minimum value ( 1.01) with a decrease in the coefficient λ _{m of the} hood to the minimum allowable.

The value of the kinematic coefficient K _{v1 of the} container of more than 1.4 is impractical to use due to the excessive localization of shear deformation in the output part of the product, which leads to intensive dynamic recrystallization of the structure of the extrudable metal and, as a result, to a decrease in the level of mechanical properties of the products.

In the same way, it is impractical to start the process when the value of the kinematic coefficient K _{v1 of the} container is less than 1.15, because while the efficiency of the process is reduced, which affects the productivity of the process.

 In this case, the maximum value of the specified ratio should be chosen based on the value of the total cross-sectional area of all pairs of cylinders stabilizing the speed of movement of the short press stamp.

During the extrusion of the workpiece 1, the ratio V _m / V _{r of the} speed V _{m of the} movement of the needle 4 and the speed V _{r of the} movement of the stamp 6 can be gradually reduced from 1.05 to 1.01. When the hollow articles are deformed under the conditions of the active action of the friction forces, the friction stress τ _am gradually increases on the surface of the workpiece 1 at the needle 4, which leads to an additional shift of the metal. This leads to a large structural heterogeneity in the back of the hollow product. To reduce the intensity of the increase in the friction stress by the end of the process, it is possible to gradually decrease the speed V _{m of the} needle 4 to a ratio of V _m / V _r less than 1.01, since the level of compressive stresses at the rear of the surface of the workpiece 1 is insufficient to significantly improve the surface quality of the finished product.

During the extrusion of the workpiece 1, the speed V _{r of the} movement of the short press stamp 6 can be changed in accordance with the temperature field of the workpiece 1.

 Under conditions of extrusion through an insufficiently heated matrix 5 and a short press stamp 6 at a heating temperature of the container 3 below the heating temperature of the workpiece 1, the back of the workpiece 1 can cool down, and this, in turn, affects the level of mechanical properties of the products.

 To obtain uniform mechanical properties and increase productivity, it is necessary to smoothly change the extrusion speed during the process. For example, with decreasing temperature of the workpiece 1 during the process, it is necessary to increase the speed of extrusion.

 In the process of extrusion as a result of the work of deformation, the workpiece 1 is heated, which significantly increases its initial temperature. The amount of heat generated depends on the speed of extrusion.

 The change in temperature of the workpiece 1 during the extrusion process affects the conditions of the dynamic recrystallization of the structure occurring in it, which significantly affects the level of the mechanical properties of the metal and their distribution along the length of the products. This circumstance is in many cases undesirable. Heating the workpiece 1 according to the proposed method, when the temperature of the front end is about 1.2-1.5 times higher than the temperature of the rear end, allows you to compensate for the generated deformation heat. In the process of extrusion in the workpiece 1, heat exchange processes with the working tool take place, so the residence time of the workpiece 1 in the sleeve 2 of the container 3 should be as small as possible. Therefore, when using a high-speed extrusion method with the active action of friction forces, it is most effective to use gradient-heated preforms 1, extruded at a gradually increasing speed.

Heating the front end of the hollow billet 1 in the range of 0.75-0.9 from the temperature of the upper boundary of the range of technological plasticity of the extrudable material allows you to start the process with the required extrusion speed, while the products have no defects in the form of transverse cracks. For example, for difficult-to-deform aluminum alloys, this temperature is approximately 340-420 ^o C. If the front end of the billet is heated below 0.75 of the temperature of the technological plasticity of the extrudable metal, then there is a noticeable decrease in the speed of extrusion at the initial stage, which leads to a significant increase in force extruding. If the front end of the workpiece 1 is heated above 0.9 from the temperature of the upper boundary of the range of technological plasticity of the extrudable metal, then at the initial stage defects in the form of transverse cracks form on the products. To eliminate them, it is necessary to significantly reduce the speed of extrusion, which leads to a decrease in the productivity of the process.

 If the back end of the workpiece 1 is heated above 0.7 from the temperature of the upper boundary of the technological plasticity range of the extrudable material, then at the end of the process not all deformation heat is compensated, and the workpiece 1 begins to overheat. To eliminate the appearance of cracks on products, it is necessary to reduce the speed of extrusion.

 When the temperature of the rear end of the workpiece 1 is lower than 0.6 from the temperature of the upper boundary of the range of technological plasticity of the extrudable material, then by the end of the process the temperature of the workpiece 1 decreases. The energy cost of deforming the workpiece 1 increases, the extrusion force increases, and the process speed decreases. It also leads to reduced performance. In addition, a change in the temperature of the workpiece 1 during deformation leads to uneven distribution of mechanical properties along the length of the products.

 The choice of temperature gradient along the length of the workpiece 1 depends on the thickness of its wall. The thicker the wall of the workpiece 1, the smaller the temperature difference should be. The workpiece 1 with a smaller wall thickness quickly redistributes heat and cools more intensively, and therefore it is necessary to provide a larger temperature gradient along its length.

 In the process of extruding the preform 1, its temperature and the heating temperature of the container 3 can be set in the range from about 1.0 to 0.95 of the heating temperature of the front end of the preform 1.

 In the process of feeding the preform 1 to the sleeve 2 of the container 3, taking into account the conditions of its preheating, the initial temperature field in the preform can vary from interaction with the sleeve 2, the die 5, the needle 4 and the short press stamp 6 even before the extrusion begins. Typically, the heating temperature of all of the above tools is set below the temperature of the front of the gradient heated preform 1, because this contributes to the additional removal of heat generated from the crimp zone, which affects the increase in tool life.

 However, excessive cooling of the extrudable preform 1 can lead to significant cooling of the back of the preform 1, which will affect the increase in deformation resistance, lowering the temperature of the onset of recrystallization of the structure, which will cause a decrease in the speed of extrusion at the final stage of the process. At the same time, not only the productivity of the press decreases, but also the degree of dynamic recrystallization in the back of the products increases, which leads to a decrease in the level of physical and mechanical properties of the products.

 The heating of the sleeve 2 of the container 3 in the range of about 0.95-1.0 from the heating temperature of the front end of the workpiece allows you to create conditions close to isothermal in the crimp zone of the workpiece 1. Under these conditions, steady-state temperature conditions near the channel of matrix 5 are maintained throughout the process.

The heating of the container 3 in the range of 0.95-1.0 from the heating temperature of the front end of the workpiece 1 eliminates the possibility of cooling the back of the workpiece 1. For example, for hardly deformable aluminum alloys, the optimal temperature of the gradient heating of the workpiece is 380 ^o C for the front end and 280 ^{o for the back} C. Given the foregoing, in order to avoid cooling the rear end of the workpiece 1, it is necessary to heat the container 3 to a temperature of 380-360 ^o C.

If the front end of the workpiece 1 is heated above 380 ^o C, then at the initial stage defects may form on the products in the form of transverse cracks. To eliminate them, it is necessary to significantly reduce the extrusion rate, which leads to a decrease in the productivity of the whole process.

If the heating temperature of the container 3 is below 360 ^o C, then part of the heat from the front of the workpiece 1 is transferred to the sleeve 2 of the container 3. This entails an increase in the resistance of the metal to deformation, which leads to an increase in force and a decrease in the speed of extrusion.

 In the process of extruding the preform 1 to the needle 4, translational movement in the direction of metal flow during cyclic loading can be reported.

 As mentioned above, in the process of extrusion of hollow products under the conditions of bilateral active action of friction forces on the workpiece 1, friction forces directed towards the outflow of metal arise from both the sleeve 2 of the container 3 and the needle 4.

The distribution of the metal structure and the indicators of mechanical properties along the wall thickness of the hollow product will depend on the gradient of the speed of movement of the metal near the channel of the matrix. The gradient, in turn, depends on the drawing coefficient and the adhesive properties of the extrudable material. Partially, the gradient can be reduced by changing the ratios V _c / V _r , V _m / V _{r of the} moving speeds V _{c of the} container 3, V _{m of the} needle 4 and V _{r of the} short press stamp 6. For this, the container 3 is moved with a speed V _{c of a} higher speed V _{m of the} needle 4, while the conditions for the interaction of the material of the needle 4 and the container 3 are significantly different compared with all known methods.

 The displacement of the workpiece metal relative to the needle 4 in the area from the front end of the stamp 6 to the border of the crimp zone (CC) is insignificant (see Fig. 1), which contributes to the adhesion of the extrudable material to the needle 4, while deteriorating the quality of the inner surface of the hollow article for the possible formation of captives, stratifications and even surface cracks. Giving the needle 4 translational movement under cyclic loading reduces the adhesion of the extrudable material to the needle 4, reduces friction stress, and also reduces the forces perceived by the needle, which increases its resistance.

 Thus, the inventive new method of hot extrusion of hollow products with the active action of friction forces allows for the highest efficiency to obtain high-quality hollow products.

 With this method, the active friction forces entrain certain contact layers of the workpiece 1, creating accelerated metal flows near the sleeve 2 of the container 3 and the needle 4. The speed of the peripheral flows relative to the speed of the short press stamp 6 is advisable to change in optimal ranges by changing the ratios of the speeds of movement of the container 3 and a short press stamp 6, and a needle 4 and a short press stamp 6, taking into account the choice of optimal temperature and speed conditions of the process.

 By reducing tensile stresses on the metal at the edge of the matrix 5, the proposed method allows to obtain the flow rate of the metal, exceeding these values by 1.5-2 times compared with all known methods of extrusion.

 By choosing the optimal temperature, speed and kinematic conditions during extrusion, it is possible to obtain high mechanical properties according to the patented method with their uniform distribution along the length and cross section of the product, with a homogeneous structure in the absence of a large crystalline rim, which are unattainable by any other extrusion methods.

 Due to the use of active friction forces on the contact surface of the end face of the workpiece at a short press stamp and their optimal regulation, it is possible to practically slow down the process of forming a press-tension and, therefore, reduce the press balance by more than 2 times and thereby increase the yield of products to 90-95%.

By creating compressive stresses τ _ac, τ _am on the surfaces of the preform 1 _, some surface microscopic defects of the products can be eliminated. In addition, optimal extrusion modes can reduce residual stresses on product surfaces. These circumstances make it possible to obtain products with increased corrosion resistance and high quality internal surface.

 In addition, the proposed method allows to achieve high speeds of extrusion and thereby reduce the residence time of the workpiece in the container, not exceeding one minute. Such conditions make it possible to use blanks with gradient heating along the length with high efficiency, which in turn makes it possible to further increase the productivity of the entire process by about 15–20%.

 The patented hydraulic extrusion press comprises a bed 9 (Fig. 3) with a front 10 and a rear 11 cross members connected by tie rods 12. On the guide rails of the bed (not shown in Fig. 3), the container 3 is mounted with the possibility of axial reciprocating movement main movable beam 13.

 The container 3 from the side of the front cross member 10 interacts with plungers 14 and 15 of the power cylinders for the reverse and direct movement of the container 3, the cylindrical bodies 16 and 17 of which are mounted on the front cross member 10. In the front cross member 10 there is a window 18 into which the extrudable product passes.

 In the nest of the front cross member 10 on the intermediate plate (the plate is not shown in FIG. 3), a long hollow press stamp 7 is installed, which together with the matrix 5 enters the cavity of the sleeve 2 of the container 3. Power cylinders are installed on the rear cross member 11: the main power cylinder, having a cylindrical body 19 and a plunger 20, and traverse reverse cylinders, having a cylindrical body 21 and plungers 22. The main plunger 20 and the return cylinder plungers 22 are rigidly connected to the main movable traverse 13.

 At least one stabilization cylinder is mounted on the rear cross member 11, having a cylindrical body 23 and a plunger 24. To reduce the overall dimensions of the press and taking into account the technology used, two or more stabilization cylinders can be installed on the press.

 In FIG. 3, as an embodiment of the inventive press, two stabilization cylinders are shown. On the rear cross member 11, as well as one of the press embodiments, cylindrical bodies 23 of stabilization cylinders can be mounted, having plungers 24 rigidly connected to the main movable traverse 13. Axis channels 25 are made in the plungers 24, which communicate with the pipeline 26. Pipelines 26 connect the inner cavity 27 of the stabilization cylinders with the inner cavity 28 of the additional cylinder having a cylindrical body 29 and a hollow plunger 30 with a shank 31 passing through the bottom of the cylindrical body 29 of the additional qi the cylinder, the cylinder 29 and the plunger 30 with the shank 31 are coaxially mounted on the main movable traverse 13.

 Pushers 32 are fixed on the traverse 13, which move the container 3. The plunger 30 of the additional cylinder has a hollow short press ram 6 mounted coaxially with the main cylinder and the press washer 33 rigidly fixed on it, inside the cavity of which the spring-loaded stitch 8 and the needle 4 are placed.

 The plunger 20 of the main power cylinder 19, as an option, is simultaneously a power cylinder for moving the needle 4. In the inner cavity 34 of the power cylinder for moving the needle 4 there is a plunger 35, rigidly connected with the needle holder 36 and with its own movable traverse 37 of the needle 4, which are installed inside the main movable traverses 13.

 The beam 37 of the needle 4 is rigidly connected with the return cylinders of the movement of the needle 4, consisting of a cylindrical body 38 and a plunger 39, one of the elements of each of which is fixed to the main movable beam 13, and the other on the movable beam 37 of the needle 4.

 From the two opposite sides, a short press stamp 6 with a press washer 33 and a needle 4 can enter the cavity of the sleeve 2 of the container 3, and, on the other hand, a long hollow press stamp 7 with a die 5, between which the pressed blank 1 is located.

 On pipelines suitable for the inner cavity 40 of the main power cylinder of the high-pressure line 41, a filling valve 42 and a speed controller 43 for moving the main movable crosshead 13 are installed.

 The inner cavity 40 of the master actuator cylinder, the inner cavity 34 of the actuator needle 4, the inner cavity 44 of the return cylinder for moving the needle 4 and the inner cavity 45 of the return cylinder of the crosshead 13 through the filling valve 42 and the dispenser 46, as well as through the corresponding valves 48, 49, 50, 51 are connected to high 41 and low 47 highways.

A valve 52 is installed on the pipe 26 connecting the inner cavity 28 of the additional cylinder with the inner cavity 27 of the stabilization cylinder, which is connected through the pipe 53 to the additional throttling device 54. In addition, the additional throttling device 54 is connected by high pressure pipes 55 and 67 through the valves 49 and 56 sec. the inner cavity 34 of the power cylinder moving the needle 4. This provides a drain of fluid from the cavity 34 of the power cylinder moving the needle 4 to maintain a given ratio V _m / V _r ck The axis V _{m of the} movement of the needle 4 and the speed V _{r of the} movement of the short press stamp 6.

 Safety valves 57 and 58 are installed in the high-pressure lines, which ensure the discharge of liquid into the low-pressure pipelines when exceeding the maximum permissible values of the liquid pressure in the line.

 On an additional pipeline 59, connecting the cavity 27 of the stabilization cylinder, a valve 60 is installed, as well as a regulator 61, in which a controlled valve 62 and a spring-loaded valve 63 are placed.

 The inner cavity 45 of the return cylinder of the movable beam 13 by a pipe 64 is connected to the high-pressure line 41. The internal cavities of 65 and 66 cylinders of the return and forward stroke of the container are connected to the same highway. The pipe 64 through the valve 68 connects the cavity 45 of the return cylinder with the pipe 41 of the high pressure line. The supply of high pressure liquid from the switchgear 46 to the inner cavity 44 of the return cylinder for moving the needle 4 is carried out through valves 50, 51 and pipe 69.

 The operation of the proposed press is provided by the tool block, shown in detail in FIG. 4.

 The tool block contains a hollow short press stamp 6, on the inner surface of which a cylindrical groove 70 is made. Inside the cavity of the short press stamp 6, a piercing 8 is installed with a flange 71 rigidly connected to the cylindrical sleeve 72 having an inner 73 and an outer 74 collar, respectively on its inner and outer surfaces. Between the housing of the short press stamp 6 and the outer surface of this sleeve 72, a spring-loaded element 75 is placed. This element 75 interacts with the outer bead 74, which is able to move inside the short press stamp 6 along the groove 70.

 The needle 4 is placed inside the piercing 8, has a cylindrical collar 77, the diameter of which corresponds to the diameter of the outer cavity of the cylindrical sleeve 72, and is equipped with a shank 78 that is rigidly connected with the needle holder 79. In the initial position, under the action of the spring element 75, the piercing end 8 is retracted to the leftmost position and is flush with the insert plane 80 of the press washer 33 and the end of the short press stamp 6.

 Press for the extrusion of hollow products with the active action of the friction forces together with the tool block (Fig. 4) works as follows.

 In the initial position, the plunger 30 of the additional cylinder is extended as far as possible from the housing 29 (to the right in Fig. 3), and the plunger 20 of the main power cylinder, plunger 35 of the power cylinder for moving the needle 4, plungers 24 of the stabilizing cylinders and plungers 22 of the return cylinders for moving the needle 4 are in the extreme left position. The container 3 at this moment is in the extreme right position.

 The heated hollow preform 1 (Fig. 2) is laid on the feeding mechanism (Fig. 5) and fixed so that approximately one third of the preform 1 is cantilevered from the side of the container 3 (Fig. 2, a). In this position, the workpiece 1 is fed to the axis of the press in the direction of arrow A. At this moment, the main movable crosshead 13 is in the extreme left position, the plunger 30 of the additional cylinder is in the extreme right position, and the needle 4 from the extreme left position is partially inserted inside the hollow workpiece 1.

 Further, by moving the container 3 to the left, the free end of the workpiece 1 is pushed into the cavity of the sleeve 2 (Fig. 2, b). After that, the feed mechanism 81 (see Fig. 5) of the workpiece 1 is retracted to its original position (Fig. 2, c). Then, the container 3 is shifted to the extreme left position, pushing the workpiece 1 completely into the sleeve 2. In this case, the hollow long press stamp 7 is released. After that, the matrix 5 is fed to the press axis using the pick-up and feed mechanism 82 (Fig. 2, d) .

 Then, through the filling valve 42, liquid is supplied from the low-pressure line 47 to the cavity 40 of the master ram. In this case, the main movable crosshead 13 makes a small idle stroke, pushing the die 5, the workpiece 1 and the short press stamp 6 with the needle 4 into the cavity of the sleeve 2 of the container 3. In this case, the pushers 32 on the main movable crosshead 13 are in contact with the container 3 and all of these movable the elements move to the right at the same speed (according to Fig. 3), and the matrix 5 after a right shift returns to its original position (Fig. 2, e).

 After clearing the gaps between the workpiece 1, the die 5 and the press washer 33, liquid is supplied from the high-pressure line 41 into the internal cavity 40 of the master ram through the same filling valve 42. In this case, the internal cavities 66 of the power cylinders of the reverse movement of the container 3 and the internal cavities 45 of the return cylinders of the movable beam 13 are first connected to the pipelines of the low-pressure line 47, and then to the pipeline of the high-pressure line 41. Thus, the idle speed passes to the compression stage, and then to the outflow of metal into the gap between the channel of the matrix 5 and the needle 4 (Fig. 2, e). At this time, fluid is discharged from cavities 45 and 66 to low-pressure line 47.

When moving to the right, the main movable yoke 13 moves the plungers 22 and 24 of the return cylinders of the yoke 13 and the stabilizing cylinders. At this moment, space 27 is gradually freed up in the cylindrical housings 23 of the stabilizing cylinders. Since pressure is transmitted through the blank 1 to the short press stamp 6, and he, in turn, transfers it to the plunger 30 of the additional cylinder, the liquid from the inner cavity 28 of the additional cylinder flows through the channel 25 into the freed inner cavity 27 of the stabilizing cylinders. This causes a smooth uniform entry of the plunger 30 into the housing 29 of the additional cylinder, which leads to the lag of the short press stamp 6 from the movement of the container 3 and the needle 4. At this point, the cavity 34 of the power cylinder of the needle 4 is closed using the valve 49. The speed V _{r of} movement short press stamp 6 at this time is determined as the difference between the speed V _{b of the} movement of the main movable crosshead 13 and the speed V _{a of the} movement of the plunger 30 of the additional cylinder
V _r = V _b - V _a (1),
where V _b is the speed of movement of the main movable beam 13;
V _a - the speed of the plunger 30 of the additional cylinder.

The speed V _{c of} movement of the container 3 is equal to the speed V _{b of the} main movable beam 13. The speed V _{b of} movement of the beam 13 and the speed V _a of the plunger 30 entering the housing 29 of the additional cylinder are oppositely directed. Therefore, the value of the kinematic coefficient K _{v1 of the} container is expressed by the formula
K _v1 = V _c / V _r = V _b / (V _b - V _a ) (2),
where K _v1 is the kinematic coefficient of the container 3;
V _c - the speed of movement of the container 3:
V _r - the speed of movement of the short press stamp 6;
V _b - the speed of movement of the main movable beam 13;
V _a - the speed of the plunger 30 of the additional cylinder.

The ratio V _c / V _{r of the} speed V _{c of the} movement of the container 3 and the speed V _{r of the} movement of the short press stamp 6 is automatically kept constant throughout the extrusion cycle.

 In this case, it is only necessary to stabilize the speed of movement of the plunger 20 of the main power cylinder 19 using the speed controller 43. This ensures the appearance on the side surface of the workpiece 1 of the friction forces of the active action.

The ratio V _c / V _{r of the} speed V _{c of the} movement of the container 3 and the speed V _{r of the} movement of the short press stamp 6 is determined by the dimensions of the inner cavity 28 of the additional cylinder and the inner cavity 27 of the stabilizing cylinders.

Closing the valves 52, 49 ensures equality of the ratios V _c / V _r , V _m / V _r .

The magnitude of the kinematic coefficient K _{v1 of the} needle is expressed by the formula
K _v2 = V _m / V _r = V _b / (V _b - V _a ) (3),
where V _m - the speed of movement of the needle 4.

 Under the above kinematic conditions, friction forces of active action arise on the inner surface of the workpiece 1 in the area from the press washer 33 to the boundary of the crimp zone C-C (see Fig. 1).

The hydraulic circuit provides for extrusion under the conditions of unilateral active action of the friction forces when the speed V _{c of} movement of the container 3 is greater than the speeds V _{r of the} short stamp 6 and V _{m of the} needle 4 (V _c > V _r = V _m ). In this case, a rigid connection of the needle holder 6 with the centering shank of the plunger 30 of the additional cylinder is provided. To implement such kinematic conditions, a special tool is required (Fig. 4).

When locking the liquid in the cavity 28 of the additional cylinder and the cavity 34 of the cylinder of the needle 4 by means of a switchgear 46 and valves 52, 49, a reverse extrusion scheme can be implemented when V _r = V _c = V _m .

It is possible to reduce the magnitude of the kinematic coefficient K _{v2 of the} needle to a predetermined value (1.01-1.05) using an additional throttling device 54. For this purpose, valves 50, 51 are opened and the high-pressure liquid flows through the distribution device 46 through the pipe 69 and through the channels in the plungers 39 in the inner cavity 44 of the return cylinder for moving the needle 4. The movement of the needle 4 towards the rear cross member 11 occurs when the valves 49, 56 are opened.

The law of change in the ratio V _m / V _{r of the} speed V _{m of the} movement of the needle 4 and the speed V _{r of the} movement of the short press stamp 6 is chosen in the optimal interval indicated above, and depending on the extrudable material and technological parameters of the process.

 After the extrusion is completed (Fig. 2, f), the fluid supply from the high-pressure line 41 is stopped by closing the filling valve 42, while the inner cavity 40 of the master cylinder through the same filling valve 42 is connected to the low-pressure line 47, and the valve 56 closes. When the valves 48, 49, 50, 51 are opened, high-pressure fluid is supplied into the inner cavity 34 of the needle-moving cylinder 4, which, moving forward, with its shoulder 77 acts on the flange 71 of the piercing 8 and advances it in the same direction. In this case, using the firmware, the press residue is separated and the product is pushed out of the matrix 5 (Fig. 2, g).

 Further, the internal cavities 45 of the return cylinders of the movable beam 37 are connected via valves 68 to the high-pressure line 41, while the short press stamp 6 and the needle 4 are moved to the left, and the cylindrical sleeve 72 remains in the extended right position (Fig. 2, g). After the shoulder 77 of the needle 4 touches the inner shoulder 73 of the cylindrical sleeve 72, the latter moves to the left and returns the piercing 8 to its original extreme left position. Fixing the position of the firmware 8 in the initial position is provided by the spring element 75.

 Then, the main movable crosshead 13 is retracted by an amount sufficient to ensure the removal of the matrix 5 with the press balance (Fig. 2, h). Then, using plungers 17, the container 3 is moved to the right until it is pressed against the front crosshead 10. This operation can be carried out with the simultaneous removal of the main movable crosshead 13. In this case, the press balance and the matrix 5 are removed from the cavity of the sleeve 2 of the container 3 and are kept from falling in this needle position 4.

 After that, the matrix is removed with a press residue and the removal mechanism and the matrix is fed 82 (see Fig. 5). In accordance with this, the matrix is clamped (Fig. 2, i) and the needle 4 is retracted together with the main movable traverse 13 to its original position (Fig. 2, j). Further, the matrix 5 with the press residue moves to the press scissors until the matrix 5 stops in the locking element, where the matrix 5 is separated from the press residue (Fig. 2, k).

 When the main movable crosshead 13 moves from the inner cavity 27 of the stabilization cylinders, the liquid is forced into the inner cavity 28 of the additional cylinder, with the extension of the plunger 30 of the additional cylinder to its original position.

 Further the cycle can be repeated.

The use of stabilizing cylinders hydraulically connected to the inner cavity of 28 additional cylinders allows automatically without any external adjustment to obtain the optimal constant value K _v1 , i.e., to fully implement the proposed extrusion method. The design of the press allows you to automatically maintain the necessary optimal ratio K _v1 even with a constant change in the speed of the plunger 20 of the main power cylinder and, accordingly, the main movable crosshead 13.

 The design of the stabilizing cylinders is very simple and they can be installed without any difficulty on any press.

 Additional pipe 59 provides the main movable crosshead 13 the ability to idle any size. In the absence of this connection, when the yoke 13 moves in the internal cavities 27 of the stabilizing cylinders, space is freed up, while there is no pressure on the short press stamp 6. This leads to the fact that in the inner cavity 27 of the stabilization cylinders can be created vacuum.

For a given value of K _v1, the cross-sectional area F _{2 of the} plunger 24 of the stabilizing cylinder is selected from the relation
F ₂ = F ₁ (1 - 1 / K _v1 ) (4),
where F ₂ is the cross-sectional area of the plunger 24 of the stabilizing cylinder;
F ₁ - the cross-sectional area of the plunger 30 of the additional cylinder;
K _v1 - the ratio V _c / V _r .

The length H _{1 of the} inner working 28 cavity of the additional cylinder is
H ₁ = H _p (1 - 1 / K _v1 ) (5),
where H ₁ is the length of the inner working cavity 28 of the additional cylinder;
H _p - the maximum length of the stroke of the plunger 24 of the stabilizing cylinder and the main movable crosshead 13.

In the presence of several stabilization cylinders, the area F _{2 of} their cross section is summed ΣF ₂ .
At least two forcing-returning power cylinders can be installed on the hydraulic extrusion press (Fig. 5), each of which is made in the form of a cylindrical body 83 with a step plunger 84 located therein. One of these elements of each forcing-returning power cylinder can be fixedly mounted on one of the cross members 11, and the other on the main movable traverse 13, while the inner cavity 85 of each of them communicates with the high 41 and low 47 fluid pressure lines.

 With this embodiment, the hydraulic press, if necessary, to idle the liquid from the high-pressure line 41 is supplied only to the internal cavity 85 of the forcing-return cylinders. At this time, only liquid from the low-pressure line 47 enters the inner cavity 40 of the master cylinder.

 To make the working stroke of the main movable crosshead 13 into the inner cavity 40 of the main power cylinder, the fluid supply from the low-pressure line 47 is stopped and the liquid begins to flow from the high-pressure line 41. It is possible to continue to supply liquid from the high-pressure line 41 to the boost-return cylinders if only the main ram cylinder is sufficient for extruding hollow products. In this case, liquid is supplied from the low-pressure line 47 to the internal cavities 85 of the boost-return cylinders.

 In a hydraulic extrusion press, the internal cavity 85 of each of the boost-return cylinders can be hydraulically connected through the axial channel 86 in the plunger 84, pipe 87, valve 88 and pipe 89 with the internal cavity 28 of the additional cylinder.

 This hydraulic coupling allows the use of boost-return cylinders in addition to stabilizing cylinders.

 In a hydraulic extrusion press, the internal cavities 85 and 27 are connected via lines 89 and 26 to the internal cavity of the additional cylinder. The cavities 85 and 27 are also connected through an additional pipe 59 to the high 41 and low 47 pressure lines using valves 60, 90, 91.

 Before starting the press, valves 60 and 90 are open. At the beginning of idling of the main movable crosshead 13 through the valves 90, 91 into the internal cavity 85 of the forcing-return cylinders, fluid flows from the high-pressure line 41. At the same time, fluid is supplied through the valve 60 to the stabilization cylinders from the low pressure line 47.

 During idling of the main movable crosshead 13 and the subsequent stage of extrusion of the workpiece 1, the valves 52 and 88 are closed. After the unpressing of the workpiece 1, the valves 60 and 90 are closed, and the valves 52 and 88 open. In this case, the plunger 30 displaces the liquid from the inner cavity 28 into the inner cavity 27 of the stabilization cylinder and the inner cavity 85 of the boost-return cylinder.

As already described above, as a result of this, the plunger 30 of the additional cylinder makes a return stroke at a given speed. In this case, the speed V _{r of the} movement of the short stamp 6 becomes less than the speed V _{c of the} movement of the container 3. On the surfaces of the workpiece 1 there are friction forces of the active action τ _ac directed towards the outflow of the metal. Since in addition to the stabilization cylinders, fluid flows from the inner cavity 28 of the additional cylinder into the cavity 85 of the forcing-return cylinders, the lag of the short press stamp 6 will be greater than if only stabilizing cylinders are connected. This allows you to expand the intervals of the ratios V _c / V _r and V _m / V _r .

Thus, using various combinations of the inclusion of stabilizing and boost-return cylinders, performed using valves 52 and 88, it is possible to automatically obtain different ratios V _c / V _r , V _m / V on the press within the working stroke of the main movable crosshead 13 _r .

The hydraulic extrusion press may contain an additional throttling device (Fig. 6), consisting of a housing 94 with four holes: two inlet 95, 96 and two outlet 97, 98. A slide valve 99 with two through cavities 100, 101 is installed inside the housing. On the right side a spring element 102 acts on the spool 99. On the left side, the spool 99 is limited by the housing 103 of the hydraulic actuator for moving the spool. The plunger 104 of this cylinder is rigidly fixed at one end to the spool 99. The configuration and geometric dimensions of the through cavities 100, 101 determine the ratios V _c / V _r and V _m / V _r .

 The cavity 100 by means of a pipe 93 through an opening 95 in the housing 94 is connected with the internal cavity 28 of the additional cylinder, and the cavity 101 by means of a pipe 67 through a similar hole is connected with the internal cavity 34 of the force cylinder of the needle 4. On the opposite side are through cavities 100, 101 in the spool 99 through the outlet openings 97, 98 in the housing 94 are connected to the lines 47 of low pressure using pipelines 105, 106.

The inner cavity 107 of the power cylinder moving the spool 99 using the pipe 53 is also connected with the inner cavity 28 of the additional cylinder. A cover 108 is mounted on the housing 94 of the additional throttling device 54 from the side of the spring element 102, which provides for the adjustment of the compression force of the spring element 102, which allows you to set the necessary ratios V _c / V _r , V _m / V _r . The spool 99 (see Fig. 6) may have through windows 100, 101 of variable cross section, both solid and with jumpers 109 (Fig. 7). The internal cavities 28, 34, through valves 92, 56 are connected with the through cavities 100, 101 of the spool 99. Additional adjustment of the throttling device is carried out using the lead screw 110 by choosing one or another ratio V _c / V _r and V _m / V _r . The lead screw 110 is fixedly mounted on the end face of the spool 99 from the side of the spring element 102. The cover 108 has a through hole for the passage of the lead screw 110.

 Such a press works as follows.

 After placing the heated workpiece 1 (Fig. 5), high pressure is supplied to the sleeve 2 of the container 3 in the internal cavities 85 of the forcing-return cylinders through the open valves 91, 90. After that, the main movable crosshead 13 starts to idle. While the valve 60 is open, and the filling valve 42 is closed to the high pressure fluid and open to the low pressure fluid. Therefore, low-pressure liquid enters the inner cavity 40 of the master ram and the inner cavities 27 of the stabilizing cylinders. In this case, the valves 52, 56, 88 and 92 are closed. After the short press stamp 6 comes into contact with the workpiece 1, and that, in turn, with the matrix 5, the filling valve 42 opens the high-pressure line and closes the low-pressure line.

The stage of extrusion and the outflow of metal into the gap between the channel of the matrix 5 and the needle 4 begins. At the same time, the valves 60, 90, 91 are closed, and the valves 52, 88, 92 and 56 open all at once or in a certain sequence. The liquid from the inner cavity 28 of the additional cylinder begins to flow into the cavities 27, 85 of the stabilizing and boost-return cylinders and through the valve 92 it goes to the through hole 100 in the spool 99 and to the inner cavity 107 of the power cylinder for moving the spool 99. At the same time, the valves 51, 50 and the high-pressure fluid through the dispenser 46 enters the internal cavities 44 of the return cylinders for moving the needle 4. In the event that the valve 49 is closed, the needle 4 moves during the extrusion process otovki container 1 with a speed of 3 (V _m = V _c). To fulfill the condition (V _m <V _c ), valves 49, 56 are opened and the liquid from the inner cavity 34 of the needle movement cylinder 4, under the pressure created in the inner cavities 44 of the needle return cylinder, begins to be displaced through the opening 101 in the spool 99 and through the outlet 98 and pipeline 106 enters the low pressure line 47. In this case, the needle 4 together with the needle holder 36 and the plunger 35 is retracted backward and its speed V _{m of} movement towards the outflow of metal will be less than the speed V _{c of} movement of the container 3 (V _m <V _c ).

Under the influence of the extrusion force transmitted to the press stamp 6 and the needle 4, the working fluid is displaced from the cavities 28 and 34 of the additional and power cylinders for moving the needle through open valves 52, 88, which ensures that the ratios V _c / V _r and V _m / V _r .

 The fluid from the inner cavity 28 of the additional cylinder simultaneously acts on the plunger 104 of the additional throttling device 54, while the plunger 104 acts on the spool 99, moving it to the right (Fig. 6). This movement is counteracted by the spring element 102, which abuts against the spool 99 on one side and the cover 108 on the other. During the extrusion process, the side surface of the workpiece 1 decreases, so the proportion of the force transmitted to the workpiece 1 through the container 3 also decreases, and the proportion of the force transmitted through a short stamp 6, increases. As a result, the pressure in the inner cavity 28 of the additional cylinder is constantly increasing, and therefore, the force on the plungers 30 and 104 of the additional and power cylinders for moving the spool 99 increases. Under the influence of this force, the plunger 104 and the spool 99 continuously move to the right, compressing the spring element 102. When moving the spool 99, its through holes 100, 101 at different points in time will be differently located relative to the input 95, 96 and output 97, 98 holes in the housing 94 additional dross a liating device (Fig. 6).

Through holes 100, 101 (Fig. 7, a) are made of constant or variable cross-section along the length of the spool 99. The hole associated with the inner cavity 34 of the force cylinder for moving the needle 4 has jumpers 109 (see Fig. 7, b, c), providing translational movement of the needle 4 during its cyclic loading. This allows you to reduce the adhesion of the metal to the needle 4, which improves the quality of the inner surface of the resulting hollow product. As a result of this, the reverse speed of the plungers 30, 35 of the additional and power cylinders for moving the needle will be variable. Thus, the ratios V _c / V _r , V _m / V _r can be both variable and constant throughout the extrusion cycle.

 The above additional throttling device is universal, providing additional displacement of fluid from the cavities 28, 34 both simultaneously and separately.

The design of the press (Fig. 8) includes a system for stabilizing the speed V _{c of the} movement of the needle 4 with respect to the speed V _{r of the} movement of the short press stamp 6.

 This system includes: an intermediate movable yoke 111 fixed to the hollow plunger 30 of the additional cylinder, rigidly connected to at least one intermediate cylinder, consisting of a cylindrical body 112 and the plunger 113. One of the elements of this cylinder is rigidly connected to the intermediate movable yoke 111, and the other with the main movable traverse 13. The inner cavity 114 of the intermediate cylinder through the valve 115 and the pipe 116 is connected with the inner cavity 44 of the return cylinder of the needle 4. Additionally, the inner spine 44 of the return cylinder through the valves 50, 51, conduit 69 and the dispenser 46 is connected to the high pressure manifold 41.

 The cavity 34 of the power cylinder for moving the needle 4 through the valves 49 and 119 and the pipe 117 is connected to the internal cavity 85 of the forcing-return cylinders, and through the valve 91 to the high-pressure line 41. The connection of the other cylinder cavities with the lines and the arrangement of the valves are identical to the hydraulic circuits described above, shown in FIG. 3 and 5.

 The operation of the press shown in FIG. 8 is basically similar to that described above in FIG. 5.

 Before extrusion begins, the internal cavity 28 of the additional cylinder communicates with the low-pressure line 47 through a pipe 26, a valve 52, a channel 25 in the plunger 24 of the stabilizing cylinder and its cavity 27, valves 60, 91 and the filling valve 42. An inner cavity 114 of the intermediate cylinder is connected to the same line through valves 115, pipeline 116, a channel in the cavity of the plunger 39 of the return cylinder for moving the needle 4, pipe 69, valves 51, 50 and switchgear 46. At this point, valve 49 is temporarily closed.

 After supplying the workpiece 1 to the cavity of the sleeve 2 of the container 3, the valve 49 opens and the dispenser 46 is actuated so that the fluid enters the cavity 34 of the force cylinder for moving the needle 4. As a result, the plunger 35 moves the needle holder 36 and the needle 4 through the hollow short stamp 6 and the hole in the workpiece 1 and sets the needle in the channel of the matrix 5. After that, using the valve 49, the pipe 55 is closed, while the working fluid remains in the cavity 34 of the needle cylinder, and with the valve 52 - the pipe 26, while cavity 28 of the additional cylinder also remains the working fluid.

If necessary, to extrude under conditions of equal speeds of movement of the container 3 and the needle 6 (V _c = V _m ), the working fluid in the inner cavity 34 of the force cylinder moving the needle 4 is locked using the valve 49. During the extrusion process, together with the main movable traverse 13 moves as one the whole additional cylinder, and the pushers 32 fixed on the traverse 13 abut their ends against the container 3, bringing the latter into joint movement.

To fulfill the specified ratio V _m / V _r , valves 115 and 49 are opened. Since the internal cavities 114 and 44 of the intermediate precise and return cylinders are disconnected from the high-pressure line 41 by closing the valve 51 before extruding, the fluid from the inner cavity 34 of the needle moving cylinder 4 under the action of the plunger 39, the return cylinder enters through the valve 49, pipe 117, valve 119 into the internal cavity 85 of the boost-return cylinder. In this case, the valve 68 is open and the fluid from the cavity 45 of the return cylinder of the movable crosshead is forced into the low-pressure line 47. Moreover, the closed valve 60 eliminates the possibility of draining the fluid into the low-pressure line 47 from the stabilizing cylinders during the working stroke of the main movable crosshead 13.

The extrusion speed is determined by the difference in the speed of movement of the main movable crosshead 13 and the speed of the reverse stroke of the plunger 30 of the additional cylinder. The stabilizing cylinder 23 provides a constant difference between the speed V _{s of the} movement of the container 3 and the speed V _{r of the} movement of the short press stamp 6.

Additional possibilities for changing the kinematic coefficient K _{v1 of the} container appear when using an additional throttling device 54 (its operation is described above).

The displacement of fluid from the inner cavity 114 of the intermediate cylinder through the valve 115 into the inner cavity 44 of the return cylinder 4 to move the needle 4 and the simultaneous flow of fluid from the inner cavity 34 of the power cylinder to move the needle 4 into the inner cavity 85 of the force-return cylinder with the valves 49, 119 open and the valve closed 90 ensures the fulfillment of a predetermined ratio V _m / V _r .

In this case, the following kinematic conditions are satisfied
V _c > V _m > V _r
K _v1 = V _c / V _r = const,
K _v2 = V _m / V _r = const,
K _v3 = K _v1 / K _v2 = V _c / V _m = const.

The scheme is universal and allows you to quickly switch to the reverse extrusion method by locking the liquid in the internal cavities 28 and 34 of the additional and power cylinders for moving the needle 4 using valves 49, 51, 52 and 115. In this case, the speed of movement of the short press stamp 6, container 3 and needles 4 are equal (V _r = V _c = V _m ).

The calculation of the parameters of all cylinders is based on the fact that the plunger 20 of the main power cylinder makes the stroke by the same amount as the plunger 84 (F ₄ ) of the forcing-return cylinder and the cylindrical body 23 (F ₂ ) of the stabilizing cylinder. The plunger 30 of the additional cylinder (F ₁ ) when making a reverse stroke moves to the length of the working cavity equal to H ₁ . Therefore, to maintain K _v1 constant, it is necessary to maintain the relations
F ₁ H ₁ = F ₂ H _p (6),
F ₂ = F ₁ (H ₁ / H _p ) (7),
where F ₁ is the cross-sectional area of the plunger 30 of the additional cylinder;
F ₂ - the total cross-sectional area of the plungers 24 stabilizing cylinders;
H ₁ - the length of the working cavity 40 of the main cylinder of the press.

Given that
K _v1 = H _p / (H _p -H ₁ ) (8),
H ₁ / H _p = 1-1 / K _v1 (9),
hence
F ₂ = F ₁ (1-1 / K _v1 ) (10)
A similar relationship is established between the areas F _{3 of the} plunger 35 of the force cylinder for moving the needle 4 and F _{4 of the} plunger 84 of the forcing-return cylinder.

To ensure the constancy of the kinematic coefficient K _v3
K _v3 = H _p / (H _p -H ₂ ) (11)
the condition is necessary
F ₄ = F ₃ (1-1 / K _v3 ) (12),
where F ₃ - the cross-sectional area of the plunger 35 of the power cylinder moving the needle 4;
F ₄ - the total cross-sectional area of the plungers 84 forcing-return cylinders;
H ₂ - the amount of movement of the needle 4 relative to the stamp.

When the needle 4 moves in the opposite direction, the plunger 35 of the force cylinder for moving the needle 4 and the body 38 of the return cylinder for moving the needle (F ₅ ) make the same movement H ₂ equal to the length of the working part of the inner cavity of the power cylinder for moving the needle 4. This is a movement for plungers 113 (F ₆ ) the intermediate cylinders is equal to the length of the working part of the inner cavity 28 of the additional cylinder. Then the relations
F ₆ H ₁ = F ₅ H ₂ (13),
F ₆ = F ₅ (H ₂ / H ₁ ) (14),
H ₁ = H _p (1-1 / K _v1 ) (15),
H ₂ = H _p (1-1 / K _v2 ) (16),
F ₆ = F ₅ (H _p (1-1 / K _v3 ) / H _p (1-1 / K _v1 ) (17)
F ₆ = F ₅ (1-1 / K _v3 ) / (1-1 / K _v1 ) (18),
where F ₅ is the total cross-sectional area of the plungers 39 return needle movement cylinders;
F ₆ is the total cross-sectional area of the plungers 113 of the intermediate cylinders.

 The design of the patented hydraulic press is simple and reliable due to the use of dependent drives for moving the container, a short press stamp and a needle, when the specified kinematic conditions are automatically maintained throughout the work cycle, regardless of the speed of movement of the main movable crosshead. The extrusion force in this case is 15-20% lower than the direct extrusion method and 5-10% higher than the reverse method.

 Placing an additional cylinder inside the main movable traverse allows up to 20% reduction in the length of the press compared to presses with separate drives for moving the container, the stamp and the needle.

 Performing the functions of forcing, returning and stabilizing cylinders with one pair of universal cylinders significantly simplifies the design of the press, reduces its metal consumption, facilitates its maintenance and reduces the overall dimensions of the press.

 The use of an easy-to-use universal hydraulic additional throttling device designed to fulfill the specified kinematic conditions for both the container and the needle allows you to significantly expand the technological capabilities of the press without the use of complicated electronic programmed speed controllers.

 A new solution is the use of a cylinder system that stabilizes the speed of movement of the container and the needle.

 In the proposed press, by simply switching the valves installed on the high and low pressure lines, one or another ratio of the speeds of the container, the short press stamp and the needle necessary for the manufacture of specific products is achieved.

 The cost of manufacturing a press is 10-15% higher than the cost of manufacturing a back press, but this is offset by an increase in productivity and an improvement in the quality of the resulting products.

 The proposed hydraulic extrusion press due to the rational design has small overall dimensions due to low metal consumption, has a small auxiliary time and a high utilization rate of the workpiece metal. The productivity of such a press is 2-2.5 times higher than the productivity of a direct-acting press and 1.3-1.8 times the productivity of a reverse-acting press.

Claims (25)

1. The method of hot extrusion of hollow products with the active action of friction, including heating the hollow billet to be extruded, placing a container in the sleeve into which a needle is passed through the cavity of this billet, extruding the billet using a short press stamp through the matrix channel and the needle formed the annular gap, which determines the shape and geometric dimensions of the finished product, during extrusion, the ratio of the speeds of movement of the stamp, container and needle is maintained in a certain interval, characterized in that during the extrusion rate v _c transferring the container exceeds the speed v _r displacement short ram 1.01 - 1.4 times, and the velocity v _m move the needle exceeds speed v _r displacement short ram 1 , 01 - 1.05 times, while the ratio of the speed v _{c of} moving the container and the speed v _{m of} moving the needle is selected in the range of 1.02 - 1.33 depending on the drawing coefficient and temperature gradient. 2. The method according to claim 1, characterized in that during the extrusion process the ratios v _c / v _r , v _m / v _{r of the} speed v _{c of} movement of the container and the speed v _{r of} movement of the short press stamp, and also the speed of v _{m of} the needle movement are changed and speed v _{r the} movement of the short stamp. 3. The method according to claim 1 or 2, characterized in that in the extrusion process, the ratio v _c / v _r of the container moving speed and the moving speed v _{r of} the short press stamp varies from 1.01 to 1.4 according to any given law, depending on the magnitude of the hood coefficient and the accepted temperature and speed conditions of the process. 4. The method according to claim 2 or 3, characterized in that in the extrusion process, the ratio v _m / v _{r of} speed v _{m of} movement of the needle and speed v _{r of} movement of the short press stamp is reduced from 1.05 to 1.01. 5. The method according to any one of claims 1 to 4, characterized in that during the extrusion process, the speed v _{r of the} movement of the short press stamp is changed depending on the distribution of the temperature gradient along the length of the workpiece.  6. The method according to any one of claims 1 to 5, characterized in that the front end of the preform is heated in the temperature range from 0.75 to 0.9, the temperature of the upper boundary of the interval of technological plasticity of the extrudable material, and the rear end of the preform is heated in the temperature range 0, 6 to 0.7 of the temperature of the upper boundary of the range of technological plasticity of the extrudable material, depending on the wall thickness of the extrudable workpiece.  7. The method according to claim 6, characterized in that before extrusion the heating temperature of the container is set in the range from 0.1 to 0.95 of the heating temperature of the front end of the workpiece.  8. The method according to any one of claims 1 to 7, characterized in that the needle is informed of a cyclic translational movement in the direction of metal outflow due to cyclic loading. 9. The method according to any one of claims 1 to 8, characterized in that for a constant ratio of the speed v _{c of} moving the container to the speed v _{r of} moving the short press stamp, the maximum value of this ratio is determined by the total cross-sectional area of all pairs of cylinders that stabilize the speed v _c moving the short stamp.  10. A hydraulic extrusion press for producing hollow products, comprising front and rear cross members rigidly mounted on the bed, a container mounted with the possibility of reciprocating movement along the longitudinal axis of the press, a main movable crosshead with a plunger rigidly fixed to it, at least one power cylinder , the casing of which is fixedly mounted on the rear cross member, and the internal cavity is connected to the high and low pressure lines, an additional cylinder associated with the main movable a traverse, the inner cavity of which is connected through a throttling device to the low-pressure line, a short stamp fixed on the plunger of the additional cylinder, and a hollow long press stamp fixed on the front cross member coaxially with the short press stamp, characterized in that the short press -the stamp is hollow and at the same time with a press washer, a needle is installed in its cavity with a needle holder connected to the plunger of the force cylinder of the needle and its movable traverse located inside the main movable the traverse, the press is equipped with a piercing with a flange, a cylindrical sleeve with collars made respectively on its inner and outer surfaces, and a spring-loaded element located between the body of the short press stamp and the outer surface of the cylindrical sleeve, while the piercing with the flange is installed inside the short press stamp and rigidly connected to the cylindrical sleeve, and the needle is placed inside the piercing and is made with a cylindrical shoulder, the outer diameter of which corresponds to the inner diameter of the cylindrical tulkus and rigidly connected to the needle holder by the shank.  11. The press of claim 10, characterized in that the plunger of the additional cylinder is installed inside the main movable beam, made hollow and provided with a centering shank passing through the bottom of the cylindrical body of the additional cylinder.  12. The press according to claim 10 or 11, characterized in that the main throttling device of the additional cylinder contains at least one stabilizing cylinder, which is a cylindrical body, in the inner cavity of which a plunger is located, and one of these elements of the stabilizing cylinder is mounted on the rear cross member and the other is rigidly connected to the main movable traverse, and the inner cavity of the stabilizing cylinder communicates hydraulically with the inner cavity of the additional cylinder. 13. The press of claim 12, wherein the stabilizing cylinder has a cross-sectional area equal to
F ₂ = F ₁ (1 - 1 / K _{v 1} ),
where F ₁ is the cross-sectional area of the additional cylinder;
F ₂ is the cross-sectional area of the stabilizing cylinder;
K _{v 1} - a given constant value of the ratio v _c / v _r speed v _{c the} movement of the container and speed v _{r the} movement of the short stamp. 14. Press according to claim 12 or 13, characterized in that the total cross-sectional area of all pairs of cylinders stabilizing the speed v _{r of} movement of the short press stamp is equal to
ΣF ₂ = F ₁ (1-1 / K _{v1 max} ),
where F ₁ is the cross-sectional area of the additional cylinder;
ΣF ₂ is the total cross-sectional area of all pairs of stabilizing cylinders;
K _{v 1 m a x} is the maximum ratio v _c / v _{r of} speed v _{c of} movement of the container and speed v _{r of} movement of the short press stamp.  15. Press according to any one of paragraphs.10 to 14, characterized in that it contains at least two forcing-returning power cylinders, each of which is made in the form of a cylindrical body, in the inner cavity of which there is a plunger, one of these elements of each forcing - the returnable power cylinder is fixedly mounted on one of the crossbars, and the other is rigidly connected to the main movable traverse, the internal cavity of each of them communicates with the high and low pressure fluid lines, and the internal cavity of each force the discharge-returning power cylinder is hydraulically connected to the internal cavity of the additional cylinder.  16. The press according to claim 10 or 15, characterized in that it contains one pair of return needle cylinders, each of which consists of a cylindrical body and a plunger, one of the elements of each cylinder being fixed to the main one and the other to the movable needle traverse.  17. The press according to claim 15 or 16, characterized in that it is equipped with an intermediate movable traverse rigidly connected to the plunger of the additional cylinder, and intermediate cylinders, each of which consists of a cylindrical body and plunger, the body of each of the cylinders is placed on the main movable traverse and the plunger is rigidly connected to the intermediate movable traverse.  18. Press according to claim 17, characterized in that the needle stabilization cylinders are force-returning power cylinders consisting of a cylindrical body and a plunger, one of the elements of each of them is rigidly connected to the rear cross member, and the other is also rigidly connected to the main movable traverse.  19. The press according to claim 17 or 18, characterized in that the inner cavity of the intermediate cylinder communicates with the inner cavity of the return cylinder of the needle, and the inner cavity of the power cylinder of the needle is hydraulically connected to the inner cavity of the boost-return cylinder.  20. Press according to any one of paragraphs.17 to 19, characterized in that the internal cavity of the return cylinders of the needle and the force cylinder of the needle are hydraulically connected through the corresponding valves to the high and low pressure lines.  21. Press according to any one of paragraphs.12 to 20, characterized in that the line connecting the internal cavities of each stabilization cylinder and forcing-return cylinders hydraulically connected to the internal cavity of the additional cylinder, in addition, is connected to the high and low pressure lines through the corresponding valves .  22. Press according to any one of paragraphs.12 to 21, characterized in that it comprises at least one additional throttling device having a housing with inlet and outlet openings provided with at least one cover, and spring-loaded from the side of the cover is installed inside this device a spool with two through cavities, the configuration and geometric dimensions of each of which determine the magnitude of the speed of mutual movement of the container and the short press stamp, as well as the needle and short press stamp, while one through Single cavity hydraulically connected via corresponding holes to the inner space of the auxiliary cylinder and the low pressure manifold, and the other cavity through the through-holes other appropriate fluid communication with the interior of the power cylinder of the mandrel and the low pressure manifold.  23. The press according to claim 22, characterized in that the spool of the additional throttling device is made with a window of variable cross section, inside of which jumpers are installed.  24. The press according to claim 22 or 23, characterized in that it comprises at least one valve installed in the line connecting the internal cavity of the additional cylinder with an additional throttling device.  25. Press according to any one of paragraphs.22 to 24, characterized in that it contains at least one valve mounted in the line connecting the inner cavity of the needle cylinder with an additional throttling device.

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