EP0268681B1 - Double action screw-press - Google Patents

Abstract

Double action screw-press in which the mechanism (23) for braking the external slider (9) when it approaches the lowermost position is mounted on the butt-end surface of said slider. The mechanism (23) includes a plate (24) provided with an arrangement for movement along the longitudinal axis of the screw (3), four elastic elements (31) mounted on the plate (24), two of which are kinematically connected, through a traverse (26), to a second stop (30). The latter is rotatably mounted in the traverse (26) and interacts, by its end face, with the end face of a first stop (22). The press is further provided with a third stop, rigidly connected to the frame (1) and interacting with the plate (24) when the external slider (9) approaches its lowermost position.

Description

Technical field

The present invention relates to the field of mechanical engineering and in particular relates to a double-acting screw press.

This invention can most advantageously be used in drop forging, in particular when forging individual parts in closed double dies.

The invention can be used to manufacture precision parts of complex configuration from common and difficult-to-deform metals and alloys for gear pumps, gears, clutches, stepped rollers, T-pieces, cross pieces, gas turbine engines and fuel control devices, among others. used with success.

Workpieces are machined according to the hot-die press process in closed double dies by deforming cylindrical blanks during one stroke. When using double-acting screw presses for forging in closed double dies, when the outer tappet approaches the lower end position, the die halves collide elastically, causing the outer tappet to rebound together with the upper die, which leads to the opening of the joint between the die halves. At the moment of rebound of the outer tappet, the inner tappet, with the tool attached to it, begins to move downward at increased speed, deforming the blank between the die halves when the parting joint is open, causing the metal to spill out of the die cavity and thus usually Committee leads.

Underlying state of the art

Attempts to solve the problem of the outer tappet slowing down as it approaches the lower end position, and in particular the speed of the outer tappet Bringing the die halves equal to or close to zero at the moment of joining together led to the construction of a double-acting screw press according to SU copyright certificate no. 854740, cl. B30b I / 18, published in the sheet "Discoveries, inventions, designs, trademarks" no. 30, 1981.

The screw press contains a frame with guides, a first spindle being rotatably accommodated along the longitudinal axis thereof. One end of the spindle is kinematically connected to the tappets and the other end of the spindle is rigidly connected to a flywheel which is set in rotation by any known drive. In the guides of the frame there is an outer plunger coaxial with the first spindle, which has two interconnected cavities. An internal plunger is housed in one of them, namely in the lower cavity facing the tool, and in the other cavity there is a supporting element which represents the body of a nut which is in engagement with the first spindle. The mother's body is rigidly connected to a hollow spindle, in the interior of which the first spindle is freely arranged. The hollow spindle engages with a nut which is rigidly connected to the inner plunger.

In the known screw press, a braking device is provided for braking the outer tappet as it approaches the lower end position. This braking device includes a traverse which is arranged in the guides mounted on the press frame so as to be displaceable along the longitudinal axis of the screw press, and at least two elastic elements which are rigidly attached to the frame above the outer plunger in its upper end position. A threaded hole is made in the crossbeam. The mother's body is facing the flywheel Side a screw thread that is opposite to the screw thread on the spindle. The threaded part of the nut body engages with the threaded hole in the crosshead.

When the outer tappet approaches the lower end position, the crossbeam is moved over its guides through the mother's body, which crossbeam interacts with the elastic elements.

The known construction of the double-acting screw press has a reduced efficiency because of the energy losses for overcoming the frictional forces that result in the threaded connection of the body of the mother with the cross-member when the outer plunger approaches its lower end position, when the inner plunger is displaced in order to carry out the deformation process and occur when the inner plunger returns to its original position with respect to the outer plunger.

The increased energy losses in the threaded connection can be explained by the fact that this connection has a constantly large contact area between the body of the nut and the crossbeam, which leads to an increased torque resistance of the body of the nut and the crossbeam.

In addition, the thread present on the body of the nut necessitates the production of the same from expensive alloy steel, which makes the screw press more expensive.

The attempts to increase the efficiency of the double-acting screw press due to reduced friction losses led to the creation of a screw press construction according to SU copyright certificate No. 1027056, IPC⁴ B30 BI / 18, published in the sheet "Discoveries, Inventions, Designs, Trademarks" No. 25, 1983.

The well-known screw press contains a frame Guides, wherein a spindle is rotatably supported along the longitudinal axis thereof. One end of the spindle facing the tool is kinematic with the tappets, but the other end of the spindle is rigidly connected to a flywheel which is set in rotation by any known drive. In the guides of the frame, an outer plunger is arranged concentrically to the spindle, which has two interconnected cavities. An internal plunger is housed in one cavity facing the tool and in the other cavity is a load-bearing element which represents a body of a nut which is in engagement with the first spindle. The mother's body is rigidly connected to a hollow spindle, in the interior of which the first spindle can be moved freely. The hollow spindle engages another nut which is rigidly connected to the inner plunger. On the outer wall of the mother's body, two stops are attached symmetrically to its axis. The support surface of each of these stops has an inclination with respect to the longitudinal axis of the spindle which is opposite to the inclination of the helix of the first spindle. In the known screw press, a braking device is provided for braking the outer tappet as it approaches the lower end position. This braking device contains two fixed crossbeams, each of which is rigidly connected to the frame and has at least two windows, a T-shaped groove being provided in the central part, and two movable crossbeams, each of which lies over one of the fixed crossbeams. Each of the movable trusses is spaced from each of the fixed ones, which is adjusted by adjusting screws, and has a T-shaped groove in its central part. In the T-shaped grooves of each of the movable or fixed A crossbar is attached, the lower end of which rests freely on the upper level of the outer tappet, while a stop is provided at the other end thereof, which is intended to interact with a movable bar. On the movable bar, on the side facing the mother's body, there is in its lower part a stop which is rotatable about its axis and is intended to interact with the stop which is located on the mother's body surface. Elastic elements are housed in the windows of each fixed crossbeam, with which the movable crossbeam interacts via the plungers.

When the outer plunger moves into the lower end position, each bar moves freely together with the same until the upper stop cooperates with the movable crossmember.

If the outer plunger is moved further, the stops on the body of the mother interact with the lower ledge stops before the die halves are joined. The upper ledge stops interact with the movable crossbeams, which compress the elastic elements via the plunger, creating resistance forces between the lower ledge stops and the nut body stops, the vectors of which are perpendicular to the plane of interaction of the stops. The horizontal components of the resistive forces create a torque that forces the nut body to rotate.

During operation of the known screw press, there is no rebound of the outer ram when the die halves are joined. Due to the design of the braking device in the form of two pairs of fixed and movable crossbeams, which are not kinematically connected, extended However, the changeover time of the braking device when changing the type of the parts to be manufactured, which reduces the performance of the screw press.

This design of the braking device precludes a simultaneous interaction of the lower stop of each bar of the fixed crossmember with the corresponding stop on the nut body, which leads to the generation of bending moments in the threaded connections of the nut enclosed in the body with the spindle and the nut of the inner tappet with the hollow Spindle leads, ie Canting in the threads causes. The latter shortens the life of the screw press.

Disclosure of the invention

The invention has for its object to provide a double-acting screw press, in which the braking device of the outer tappet would ensure the compensation of angular velocities of the load-bearing elements and the spindle as it approached the lower end position, thereby eliminating the rebound of the outer tappet when the die forces were combined without reducing the performance and operational reliability of the screw press and reducing the efficiency of the same. The object is achieved in that in the double-acting screw press, which has a frame with guides, a spindle being rotatably mounted along the longitudinal axis thereof, while in the frame guides, an outer tappet with guides for an inner tappet and with two is concentric with the spindle interconnected cavities, the inner plunger being in the one cavity facing the tool and the other being a supporting element with at least two symmetrical with respect to the axis of the first spindle and housed on the outer surface of the first stops, the support surface of each of which has an inclination with respect to the longitudinal axis of the spindle which is opposite to the inclination of the helix of the first spindle, which element engages with a first spindle which is in engagement with the first spindle Mother and rigidly connected to a hollow spindle, which comprises the first spindle and engages with a second nut rigidly mounted in the inner plunger, and a braking device for braking the outer plunger as it approaches the lower end position, which braking device with the supporting element is kinematically connected, according to the invention the braking device is attached to the face of the outer plunger facing the first stops and includes a plate which is coaxial with the spindle and has a through hole in which the supporting element is received, and also with one r device for displacing the first spindle along the longitudinal axis is equipped, with elastic elements being attached to the plate, a pair of which is kinematically connected via a crossbar to a second stop which is arranged dreneably in the crossbar and via its end face to the first stop cooperates, this end face is inclined and its angle of inclination corresponds to the angle of inclination of the surface of the first stop, and that further third stops are provided which are rigidly connected to the frame and when the outer plunger approaches the lower end position with the plate work together.

This design of the screw press ensures minimal energy losses due to friction, because two second stops in the traverse are arranged with two first stops on the load-bearing element Stops only cooperate within a limited section, namely within the braking section of the outer plunger as it approaches the lower end position, which leads to an increase in the efficiency of the screw press according to the invention.

The attachment of the second stops on the plate ensures their simultaneous interaction with the stops on the supporting element, which precludes the generation of bending moments in the threaded connections of the nut of the supporting element with the spindle and the nut of the inner plunger with the hollow spindle, i.e. Tilting in the threads prevented.

The only plate provided in the braking device facilitates and accelerates the changeover of the screw press when changing the type of the parts to be manufactured, which leads to an increase in the performance of the screw press. Furthermore, the mounting of the third stops in the spindle press frame, namely in the stands thereof, increases the rigidity of the braking device, which prevents canting between the plate and the frame when the stops on the supporting element interact with the second stops when braking the outer tappet.

The arrangement of the plate on the upper end face of the outer tappet ensures the same an unimpeded displacement up to the upper or lower end position, which simplifies the construction of the screw press, its metal content and the dimensions are reduced. In addition, the arrangement of the plate on the outer plunger shortens the plate stroke in the guides and reduces the dimensions of the same.

On the outer surface of the load-bearing element, two profile surfaces forming a cam are to be provided, which interact with two spring-loaded push elements which are symmetrical with respect to the axis of the load-bearing element, each of them in guides on the plate surface is arranged, which is opposite to the surface in which it cooperates with the third stop, and has an inclined surface, which is intended to cooperate with the inclined surface of the third stop at the end of braking of the outer plunger.

The execution on the outer surface of the load-bearing element of two profile surfaces and the presence of two abutment elements, which are arranged on a plate and interact with the third stops fixed in the frame, ensure a successive displacement of the inner and outer plunger during their upward movement after the deformation process has ended, what leads to a stable production process of die forging, namely to maintain the specified sequence of movements of the tools: the die connected to the inner plunger and the upper die connected to the outer plunger. This ensures reliable removal of the finished forgings from the die. When producing forgings with animal cavities, the punch "grips" through the workpiece, which prevents the upward movement of the inner tappet with respect to the outer tappet and the removal of the workpiece from the punch. This in turn leads to an even stronger adherence of the workpiece to the punch when it cools down, which means that the spindle press has to be switched off for the inevitable removal of the workpiece from the punch and rejects and a reduction in the spindle press performance.

worin bedeutet:

• R₁ _ mittlerer Halbmesser des Spindelgewindes;
• R₂ _ Abstand von der Spindelachse bis zur Achse des zweiten Anschlags;
• α₁ _ Neigungswinkel der Schraubenlinie am mittleren Durchmesser des Spindelgewindes.

It is recommended that the angle of inclination of the end face of the second stop, which corresponds to the angle of inclination of the support surface of the first stop and which is opposite to the inclination of the spindle helix to the horizontal plane, is given by the following relationship:

in which means:

• R₁ _ medium radius of the spindle thread;
• R₂ _ distance from the spindle axis to the axis of the second stop;
• α₁ _ angle of inclination of the helix on the average diameter of the spindle thread.

Only with such a ratio of the angles of inclination, the shutdown of the outer tappet and minimal energy losses when braking the outer tappet are guaranteed the angular velocity of the spindle is recovered, which ensures that the outer tappet is braked until it is completely stopped. This design of the brake device ensures maximum efficiency of the screw press.

Brief description of the drawings

• Fig. 1 eine schematische Darstellung der erfindungsgemäßen doppeltwirkenden Spindelpresse, mit einem teilweisen Längsschnitt;
• Fig. 2 den Schnitt nach der Linie II-II von Fig. 1;
• Fig. 3 den Schnitt nach der Linie III-III von Fig. 1;
• Fig. 4 den Schnitt nach der Linie IV-IV von Fig. 2; mit den beiden Stößeln in der unteren Endlage;
• Fig. 5 die Zusammenwirkungsebene des ersten Anschlags mit dem zweiten Anschlag und die bei deren Zusammenwirkung entstehenden Kräfte;
• Fig. 6 ein Diagramm der Änderungen der linearen Bewegungsgeschwindigkeit V des Außenstößels, der Winkelgeschwinsigkeit ω₁ der Spindel und der Winkelgeschwindigkeit ω₂ der hohlen Spindel über der Bremszeit t des Außenstößels.

The essence and the advantages of the invention are explained in the following specific exemplary embodiment thereof with reference to the accompanying drawings; it shows:

• Figure 1 is a schematic representation of the double-acting screw press according to the invention, with a partial longitudinal section.
• Figure 2 shows the section along the line II-II of Fig. 1.
• 3 shows the section along the line III-III of Fig. 1.
• Figure 4 shows the section along the line IV-IV of Fig. 2. with the two plungers in the lower end position;
• 5 shows the level of interaction of the first stop with the second stop and the forces which arise when they interact;
• Fig. 6 is a diagram of the changes in the linear movement speed V of the outer plunger, the angular velocity ω₁ of the spindle and the angular velocity ω₂ of the hollow spindle over the braking time t of the outer plunger.

Best embodiment of the invention

The double-acting screw press designed according to the invention is intended for die forging precision parts of complicated configuration made of common and difficult-to-deform metals and alloys, for example of gear wheels, couplings, T-pieces, cross pieces, etc. in closed double dies. The screw press contains a frame 1 (FIG. 1) with guides 2, a spindle 3 being rotatably mounted along the longitudinal axis thereof. One end of the spindle 3 is rigidly connected to a flywheel 4, which is set in rotation by any known drive. In a cross member 5 of the frame 1, a thrust bearing 6 and a thrust bearing 7 are present, in which the spindle 3 rotates. The guides 2 are arranged on stands 8 of the frame 1. An external plunger 9 is slidably arranged in these guides and has two interconnected cavities 10 and 11. An inner plunger 13 is accommodated in the cavity 10 facing a tool 12, and in the cavity 11 there is a part of a load-bearing element which is a bimetallic nut 14, namely its threaded part 15 made of bronze and its body 16 made of steel or cast iron is made, which mother is engaged with the spindle 3. The lower end of the spindle 3 is freely guided through a through bore 17 of a hollow spindle 18 which is rigidly connected to the body 16 of the nut 14. The hollow spindle 18 engages with a second nut 19 rigidly attached in the inner tappet 13 and is supported with its flange 18a on a track pin 20 which is rigid with the outer tappet 9 connected is. In the cavity 11 of the outer plunger 9, a thrust bearing 21 is provided on the flange 18a of the hollow spindle 18. On the outer surface of the body 16 of the nut 14, at least two first stops 22 are mounted symmetrically to the axis thereof, the supporting surface of each of them having an inclination with respect to the longitudinal axis of the spindle 3 which is opposite to the inclination of its helix.

In said screw press, a braking device 23 is provided for braking the outer plunger 9 as it approaches the lower end position. The brake device 23 mentioned contains a plate 24 which has a continuous central bore 25 which surrounds the body 16 of the nut 14 and runs coaxially with the spindle 3, and two crossbeams 2b which are kinematically connected to the plate 24. On the surface of the plate 24 (FIG. 2), spring-loaded thrust elements 28 are arranged in guides 27, which are symmetrical with respect to the axis of the body 16 of the nut 14. Furthermore, there are two sleeves 29 on the plate 24, in each of which a second stop 30 is received, and four elastic elements 31 (FIG. 1), one of which is kinematically connected to the second stop 30 via one of the cross members 26 . Each of the stops 30 is rotatably arranged in the crossmember 26 and interacts with this first stop 22 via one of its end faces, which is designed to be inclined and whose angle of inclination α₂ corresponds to the angle of inclination α₂ of the surface of the first stop 22, while using its other End face via a track bearing 32, the cross member 26, set screws 33 and a disc 34 cooperate with two elastic elements 31.

worin bedeutet:

• R₁ _ mittlerer Halbmesser des Spindelgewindes;
• R₂ _ Abstand von der Spindelachse bis zur Achse des zweiten Anschlags;
• α₁ _ Neigungswinkel der Schraubenlinie am mittleren Durchmesser des Spindelgewindes.

The angle α₂ is given by the following relationship:

in which means:

• R₁ _ medium radius of the spindle thread;
• R₂ _ distance from the spindle axis to the axis of the second stop;
• α₁ _ angle of inclination of the helix on the average diameter of the spindle thread.

Each of the crossbeams 26 is supported on the upper surface of the outer plunger 9 by means of second set screws 35. In addition, the plate 24 (FIG. 3) can be moved along the spindle axis, for which purpose it is provided with two ribs 36, each of which is accommodated in a guide 37 fastened to the outer plunger 9.

The stands 8 (Fig. 1) of the frame 1 of the screw press contain stops 38 (Fig. 4) to limit the displacement of the plate 24 (Fig. 1) as the outer plunger 9 approaches the lower end position and stops 39 (Fig. 4) Prevention of displacement of the outer plunger 9 in the upward direction until the moment when the inner plunger 13 (FIG. 1) assumes its upper end position.

On the outer surface of the body 16 of the nut 14 there are two profile surfaces 40 (FIG. 2) which form a cam and which interact with the two thrust elements 28. Each of the push elements 28 has, on the side opposite to the interaction with the cam, an inclined surface 41 which is provided for cooperation with the stop 39 (FIG. 4). Each of the push elements 28 has an interior 42 in which a spring 43 is accommodated which is connected at one end to the pushing element and at its other end presses against a pin 44 pressed into the plate 24.

The screw press works in the following way.

Before starting work, the outer plunger 9 (FIG. 1) and the hollow spindle 18, nut 14 connected to it and plate 24 raised to the upper end position. The inner plunger 13 assumes an upper end position with respect to the outer plunger 9, here the push elements 28 (FIG. 2) are pressed against the profile surfaces 40 of the cam, the first stops 22 (FIG. 1) press with their inclined surfaces against the upper one Part of the second stops 30, but with their lower end faces via the thrust bearing 32, cross members 26, set screws 33 and the second set screws 35 against the outer plunger 9.

When the spindle press drive (not shown in the drawing) is switched on, the flywheel 4 and the spindle 3 connected to it begin to rotate at high speed, and the spindle 3 unscrews the nut 14 by turning its body 16, the hollow spindle 18, the inner plunger 13 and the outer plunger 9 with the plate 24 attached to the same and the push elements 28 connected to the same, the guide sleeves 29, the second stops 30, the cross members 26, the elastic elements 31 and the set screws 33 and 35 are displaced in the downward direction . The body 16 of the nut 14 does not rotate during this downward descent stroke because it is braked (the brake is not shown).

The joint movement of the outer plunger 9 and the plate 24 continues until the latter touches the stops 38 (FIG. 4), whereupon the plate 24 comes to a standstill and remains immobile. Here, however, the outer plunger 9 (FIG. 1) does not reach its lower end position, it is an amount δ away from it and therefore continues its downward movement. The amount δ is regulated with the aid of the second set screws 35, which are adjusted after the set screws 33 have been set, which determine the end position of the body 16 of the nut 14 before starting work. The set screws are then tightened in any known manner (in the drawing not shown) locked.

The first stops 22 act on the elastic elements 31 via the second stops 30, cross members 26, first set screws 33 and washers 34. There is a force F (Fig. 5), which resists the displacement of the first stops 22 and the parts connected to them _ the body 16 of the nut 14, the hollow spindle 18, the outer plunger 9 and the inner plunger 13 and is normal to the plane of contact of the first stops 22 and the second stops 30.

worin bedeutet:

• F₂ _ horizontale Komponente der Kraft F, die auf die ersten Anschläge 22 einwirkt;
• R₂ _ Wirkungsnalbmesser der Kraft F₂ auf die ersten Anschläge 22, der dem Abstand von der Spindelachse bis zur Achse des zweiten Anschlags gleich ist.

Under the action of a force F₂, which is a component of the force F, a torque is generated on the body 16 of the nut 14:
$$\text{M₂ = F₂ · R₂}$$

in which means:

• F₂ _ horizontal component of the force F, which acts on the first stops 22;
• R₂ _ impact signal of the force F₂ on the first stops 22, which is the same distance from the spindle axis to the axis of the second stop.

worin bedeutet:

• F₁ _ vertikale Komponente der Kraft F, die auf die ersten Anschläge 22 einwirkt;
• R₁ _ mittlerer Halbmesser des Gewindes der Spindel 3;
• α₁ _ Neigungswinkel der Schraubenlinie am mittleren Durchmesser des Gewindes der Spindel 3.

$$\text{F₁ = F₃,}$$

wo F₃ eine von den elastischen Elementen 31 erzeugte Kraft bedeutet.The force F 1, which is a component of the force F, is transmitted from the first stops 22 attached to the body 16 of the nut 14 to the spindle 3 and thereby generates a torque:
$$\text{M₁ = F₁ · R₁: tg α₁,}$$

in which means:

• F₁ _ vertical component of the force F, which acts on the first stops 22;
• R₁ _ medium radius of the thread of the spindle 3;
• α₁ _ angle of inclination of the helix on the average diameter of the thread of the spindle 3rd

$$\text{F₁ = F₃,}$$

where F₃ means a force generated by the elastic elements 31.

wo α den Neigungswinkel der Stirnfläche eines jeden der ersten Anschläge 22 zur horizontalen Ebene bedeutet, der dem Neigungswinkel der Stirnfläche eines jeden der zweiten Ansbhläge 30 gleich ist.Then:
$$\text{F₂ = F₃ · tgα₂,}$$

where α is the angle of inclination of the end face of each of the first stops 22 to the horizontal plane, which is the same as the angle of inclination of the end face of each of the second stops 30.

The torques M₁ and M₂ are directed in the direction of rotation of the spindle 3 and generate a total torque M, which drives the nut 14 to an ever faster rotation in the direction of rotation of the spindle 3.
$$\text{M = M₁ + M₂}$$

worin bedeutet:

• F₃ = c·S _ von den elastischen Elementen 31 erzeugte Kraft;
• c _ reduzierte lineare Steifigkeit der elastischen Elemente 31;
• S _ Verformung der elastischen Elemente 31 beim Beschleunigen der Mutter 14.

By inserting (3) and (4) in (5) with consideration of (1) and (2), one obtains:
$$\text{M = F₃ (R₁ · tgα₁ + R₂ · tgα₂),}$$

in which means:

• F₃ = c · S _ force generated by the elastic elements 31;
• c _ reduced linear stiffness of the elastic elements 31;
• S _ deformation of the elastic elements 31 when the nut 14 accelerates.

Under the action of the total torque M, the nut 14 begins to rotate at an increased speed in the direction of rotation of the spindle 3.

worin bedeutet:

• ω₁ _ Winkelgeschwindikeit der Spindel 3;
• ω₂ _ Winkelgeschwindikeit der Mutter 14;
• h₁ _ Gewindesteigung der Spindel 3.

The displacement speed of the outer plunger 9 decreases and is determined by the following relationship:

in which means:

• ω₁ _ angular velocity of the spindle 3;
• ω₂ _ angular velocity of the nut 14;
• h 1 _ thread pitch of the spindle 3.

The angular velocity of the nut 14 can also be determined by solving the following equation of motion;

• a = R_1′tgα₁
• b = R_2′tgα₂
• ω₀ _ die Frequenz der freien Schwingungen des Systems

worin y* das reduzierte Trägheitsmoment der beweglichen Teile bedeutet.in which means:

• a = R _{1 '} tgα₁
• b = R _{2 '} tgα₂
• ω₀ _ the frequency of the free vibrations of the system

where y * means the reduced moment of inertia of the moving parts.

ω₂ = max bei cos ω₀t = -1,
Dann

bzw 2a = a + b,From the equation (8), the parameters are calculated in which the angular velocity of the nut 14 reaches the angular velocity of the spindle 3:

ω₂ = max at cos ω₀t = -1,
Then

or 2a = a + b,

So:

Mostly R₁ and α₁ are predetermined, and R₂ is determined constructively, then applies;

The braking process of the outer plunger 9 is composed of two stages. In the first stage, when the rotational speed of the nut 14 is low, the compression of the elastic elements 31 takes place with the accumulation of the potential energy of the elastic deformation of the elastic elements 31. In the second stage, the nut 14 is accelerated and the plunger 9 is braked due to the stored potential energy of the elastic elements 31, which is converted into the kinetic energy of the rotation of the nut 14.

The braking distance δ of the outer tappet 9 is predetermined in such a way that during the braking stroke of the outer tappet 9 when the potential is completely released Energy of elastic deformation of the elastic elements 31 for accelerating the nut 14, the angular velocity ω₂ (Fig. 6) of the nut 14, the angular velocity ω₁ of the spindle 3 is the same.

At the end of the braking stroke of the outer plunger 9 is ω₁ = ω₂, and the displacement speed V of the same is zero.

In this way, the baking of the jaws of the work tool 12 takes place smoothly.

wo h₂ die Gewindesteigung der hohlen Spindel 18 bedeutet.At the moment the jaws of the working tool 12 are joined, the displacement speed of the inner plunger 13 is 13

where h₂ means the thread pitch of the hollow spindle 18.

During the braking stroke, the body 16 of the nut 14 rotates at an angle at which the cam profile surfaces 40, which are attached to the body 16 in a controllable manner (not shown in the drawing), act on the push elements 28 with inclined surfaces, as a result of which they are forced to act to move in the radial direction up to the contact with the inclined surfaces of the stop 39. Upon further rotation of the body 16, the cam profile surfaces 40 come into contact with the abutment elements 28 on a surface of a constant radius, so that the abutment elements 28 do not make any displacements. At this moment, the working tool 12 meets the workpiece (not shown in the drawing), and a deformation stroke takes place until the energy of the moving parts has completely transferred to the deformation work on the workpiece. At the end of the deformation stroke, the body 16 of the nut 14 comes to a standstill, the drive, the flywheel 4 and the spindle 3 are reversed in the direction opposite to the angle of rotation of the body 16 during the working stroke.

The movement of the outer plunger in the upward direction is only possible in the case when the body 16 of the nut 14 has been rotated in the direction of rotation of the spindle 3 up to a position of the cam profile surfaces 40 which ensure the displacement of the push elements 28 towards the center. The rotation of the body 16 enables the inner plunger 13 to be raised into the upper end position with respect to the outer plunger 9, the first stops 22 coming into contact with the inclined surfaces of the second stops 30 via their inclined surfaces. Then the body 16 of the nut 14 comes to a standstill and the moving parts are raised to the upper end position. When the moving parts approach the upper end position, the drive is switched off and the brake of the flywheel 4 (not shown in the drawing, is switched off when the "downward stroke" working cycle is switched on). The work cycle has ended.

Commercial usability

The construction of the double-acting screw press proposed according to the invention ensures the specified workflow, i.e. a bumpless connection of the working tool and the successive movement of the inner plunger in the upper end position with respect to the outer plunger and the subsequent joint movement of the two plungers in the upward direction after the deformation stroke has ended. This makes it possible to expand the technological possibilities of the equipment, to ensure the production of high-quality parts and to reduce the loads on the elements of the die and the screw press, but to increase their service life.

The construction of the screw press makes it possible to simplify its construction and operation, because this specialized equipment for forging in closed double dies under conditions of series and small series production is determined, which is characterized by frequent changing of the technological equipment and changing the device for bumplessly connecting the jaws and for successively moving the inner plunger with respect to the outer plunger.

• eine Metalleinsparung um 25-35%;
• eine Erhönung der Arbeitsproduktivität um 30%;
• eine Senkung des Arbeitsaufwandes um 20-25% durch Senkung der Anzahl der nachfolgenden Operationen;
• eine Verringerung der technologischen Kraft um das 1,5-2 fache;
• eine erhöhte Schmiedestückpräzision um eine Qualitätsstufe;
• eine vereinfachte Mechanisierung und Automatisierung des Gesenkschmiedevorganges.

Furthermore, the screw press is successfully used for the production of such individual parts as bushings with a flange, gear wheels with countersunk-pressed teeth. Compared to the processing of similar workpieces using the ridge drop forging process, the following is achieved:

• a metal saving of 25-35%;
• a 30% increase in labor productivity;
• a 20-25% reduction in workload by reducing the number of subsequent operations;
• a reduction in technological power by 1.5-2 times;
• increased forging precision by one quality level;
• a simplified mechanization and automation of the drop forging process.

Claims (3)

1. Double-action screw press which has a frame (1) with guideways (2), there being pivoted along the longitudinal axis of the frame a first screw (3) and there being arranged in the guideways (2) of the frame (1) so as to be concentric to the first screw (3) an outer slide (9) with guideways for an inner slide (13) and with two hollow spaces (10, 11) which communicate with each other, the inner slide (13) being accommodated in the hollow space (10) facing the tool (12), whilst there is arranged in the other hollow space a carrying element with at least two first stops (22) which lie symmetrically relative to the axis of the first screw (3) and which are provided on the outer surface of the same, the supporting surface of each of them having a slope relative to the longitudinal axis of the screw (3), opposed to the slope of the helix of the first screw (3), which element is rigidly connected with a first nut (14), which is engaged with the first screw (3), and with a hollow screw (18), which encompasses the first screw (3) and is engaged with a second nut (19) rigidly installed in the inner slide (13), and also contains a braking arrangement (23) for braking the outer slide (9) when it approaches the lower end position, which braking arrangement is kinematically connected with the carrying element, characterised in that the braking arrangement (23) is provided on the face of the outer slide (9) facing the first stops (22) and includes a plate (24) which lies coaxially relative to the screw (3), has a through bore (25) in which the carrying element is received and is also equipped with an arrangement for the purposes of displacement along the longitudinal axis of the first screw (3) and upon which there are provided elastic elements (31), one pair of which is kinematically connected by way of a cross-member (26) with a second stop (30) which is rotatably arranged in the cross-member (26) and cooperates by way of its sloping face with the first stop (22), its angle of slope corresponding with the angle of slope of the surface of the first stop (22), that, furthermore, third stops (38, 39) are provided which are rigidly connected with the frame (1) and cooperate with the plate (24) when the outer slide (9) approaches the lower end position.

2. Double-action screw press according to claim 1, characterised in that there are provided on the outer surface of the carrying element two profiled surfaces (40) which form a cam and which cooperate with two spring-mounted pushing elements (28) which lie symmetrically relative to the axis of the carrying element and each of which is arranged in guideways (27) on the surface of the plate (24), which is opposite to its surface of cooperation with a third stop (39), and has a sloping surface (41) which is intended for cooperation with the sloping surface of a third stop (38) at the end of the braking process of the outer slide (9).

3. Double-action screw press according to claims 1, 2, separately or taken in combination, characterised in that the angle of slope (α₂) of the face of the second stop (30), which corresponds with the angle of slope (α₂) of the supporting surface of the first stop (22) and is opposite to the slope of the helix of the first screw (3), is given by the following relationship:

where:

R₁ signifies mean radius of the screw thread;

R₂ signifies distance from the screw axis to the axis of the second stop;

α₁ signifies angle of slope of the helix on the mean diameter of the screw thread.

Images