Drawing carriage for a drawing machine and drawing machine

Abstract

A drawing carriage for a drawing machine, comprising two clamping jaws (23, 24) and a clamping jaw displacement device (41) for an opening and closing movement of the clamping jaws (23, 24), is characterized in that the clamping jaw displacement device (41) has at least one torque motor (29), at least one drive shaft (36) that can be driven in rotation by the at least one torque motor (29), a front part (43) that can be moved directly or indirectly via the drive shaft (36), and position detection means (48), wherein the position detection means (48) are designed to directly or indirectly detect the position of the front part (43) and / or the associated clamping jaws (23, 24). A drawing machine comprising a drive unit for driving at least two drawing carriages (1), is characterized by at least one drawing carriage (1) designed according to the invention.

Description

[0001] The invention relates to a drawing carriage for a drawing machine according to the preamble of claim 1 and to a drawing machine according to the preamble of claim 9.

[0002] Drawing machines are used to draw elongated metal objects, namely the drawn material, such as rods or tubes, through a drawing tool using at least one drawing carriage that holds the metal object. In the drawing tool, the drawn material undergoes deformation to a smaller diameter, so that, for example, a wire can be produced. Such drawing machines can therefore also be designed as wire drawing machines.

[0003] EP 3 487 644 B1 discloses a drawing carriage and a drawing machine of the type mentioned above. Two drawing carriages are arranged on a machine frame of the drawing machine and are moved by drive means in a periodic back and forth movement along a common straight line. The movement of the drawing carriages is controlled in such a way that they pull the drawn material in hand-in-hand operation, enabling an essentially continuous drawing movement. A first of the drawing carriages grips the drawn material and pulls, while the second drawing carriage moves to a starting position in order to grip the drawn material when the first drawing carriage has reached a transfer position. When the second drawing carriage begins the drawing process, the first drawing carriage has already released itself from the drawn material and in turn moves back to its starting position in order to grip and pull the drawn material again. The movement of the drawing carriages parallel to the drawing direction can, for example,by means of spatial cam gears with drawing curves or by means of linear motors.

[0004] The drawing carriages grip the material to be drawn by means of a pair of clamping jaws, which grip the material between them. According to EP 3 487 644 B1, a linear motor attached to the respective drawing carriage is used for the opening and closing movement of the clamping jaws. Compared to a pneumatic or hydraulic solution, this can result in lower costs in terms of the required mechanical components and maintenance effort. Mechanical adjustment of the clamping jaws can be eliminated. In addition, with a linear motor, the clamping jaws can be positioned more precisely, and the system's response time is shorter. Furthermore, the influence of temperature on the system is reduced or can be completely ignored.Compared to an electric motor with a rotary drive as an alternative, the advantage is that the conversion of a rotational movement into a translational movement with the necessary gear devices is not required.

[0005] JP S56 47 210 A discloses a method for producing a spiral groove with a cold-drawn cutting edge on a smooth inner surface of a metal tube. For this purpose, a tube blank is drawn through a die with the aid of a lathe chuck, with a tenon provided with spiral ribs simultaneously arranged inside the tube blank. With this movement, the diameter of the tube blank is reduced by the die, while at the same time, the ribs of the tenon continuously cold-form the spiral groove in the inner surface of the tube blank. A torque motor is used to drive the lathe chuck for its rotational movement. The closing and opening of the lathe chuck, however, is carried out by means of a hydraulic cylinder.

[0006] The invention is based on the object of providing a drawing carriage with a further improved locking mechanism for the clamping jaws. A further object is to correspondingly improve a drawing machine having at least two drawing carriages. This object is achieved with respect to the drawing carriage by the characterizing feature of claim 1.

[0007] Accordingly, it is proposed that the clamping jaw moving device has a torque motor.

[0008] The torque motor according to the invention is an electric motor optimized for high torques, preferably without its own sensor for measuring the angular position between the rotor and stator. The torque motor is preferably an electric direct drive from the group of slow-speed motors, more preferably with a high number of poles. The torque motor can be designed, for example, as a DC electric motor or as a permanently excited three-phase synchronous motor. The torque motor preferably has two essential components, namely a stator and a rotor, preferably designed as a hollow-shaft rotor. Mechanical transmission elements, in particular gears, are omitted from the torque motor, which can therefore be mounted directly on a drive shaft, so that the motor function and service life are completely unaffected by any acceleration that occurs. In addition, torque motors can have a very high power density.Depending on the motor type, the torque that can be generated can be 5 to 10 times higher than that of alternative motors, such as servo motors, of the same size. This means that the torque motor can be operated without overload, significantly increasing its service life.

[0009] The torque motor can be designed in such a way that its function and service life are completely unaffected by the accelerations it encounters. This reduces maintenance requirements and increases service life compared to alternative drive systems.

[0010] Furthermore, the clamping jaw displacement device comprises at least one drive shaft that can be rotationally driven by the at least one torque motor, a front part that can be moved directly or indirectly via the drive shaft, and position detection means, wherein the position detection means are configured to directly or indirectly detect the position of the front part and / or the associated clamping jaws. The additional effort required to provide separate position detection means compared to a servo motor is surprisingly more than compensated for by the advantages associated with the use of the torque motor.

[0011] By incorporating position sensing means, the torque motor can be designed without a rotary encoder. Limitations regarding permissible maximum accelerations that typically apply to torque motors with encoders can thus be avoided. Compared to servomotors, a torque motor offers the possibility of freely selecting the drive shaft, which also allows for improved adaptability to the specific operating conditions of a drawing carriage for a drawing machine, especially a wire drawing machine.

[0012] It is particularly advantageous that the bearing of the drive shaft can be chosen largely freely.

[0013] The drawing carriage according to the invention can be designed so that the drive shaft is mounted by means of a tapered roller bearing. This allows for a rigid mounting of the drive shaft without any problems. Alternative bearing designs are also conceivable.

[0014] For this purpose, the stator of the torque motor can be fixed to a housing part of the drawing carriage, while the rotor is fixed to the drive shaft in a rotationally fixed manner.

[0015] Furthermore, the drawing carriage according to the invention can be designed such that a transmission element is provided that converts a rotational movement of the drive shaft into a translational movement of the front part of the clamping jaw displacement device. The transmission element can be, for example, a recirculating ball sleeve, for which the drive shaft can have a threaded spindle-shaped section.

[0016] The position detection means enable control of the clamping jaw traversing device. The control system can be adapted so that the front part of the clamping jaw traversing device can essentially be formed from a simple rigid block. With regard to the drawing process, however, there is the problem that at the start of the drawing process, the clamped material exerts an enormous force on the clamping jaws and the wedge elements supporting the clamping jaws. So that after the clamping jaws close, the wedge elements and the parts of the clamping jaw traversing device engaging the wedge elements are displaced relative to the housing of the drawing carriage, counter to the drawing direction.

[0017] Therefore, the drawing carriage according to the invention can be designed such that the front part has a bridge element for transmitting the translational movement of the front part to the clamping jaws, wherein the bridge element is elastically mounted in the front part. With the elastic mounting configured for the direction of the translational movement, the force acting on the clamping jaws from the clamped drawing material at the start of the drawing process can be adequately absorbed. The elastic mounting can be implemented, for example, using disc springs.

[0018] Furthermore, the drawing carriage according to the invention can be designed such that the front part of the clamping jaw traversing device is guided on at least one linear guide aligned in the drawing direction. Position detection, for example, is possible on the linear guide.

[0019] The drawing carriage can have a drawing device and / or an inlet hopper for the drawn material. The drawing device itself can also be motor-driven, e.g., by means of a linear motor. The inlet hopper serves as a positioning aid for the drawn material to be fed into the drawing carriage.

[0020] With regard to a drawing machine, the technical problem is solved by the characterizing features of claim 9, according to which the drawing machine, which has a drive unit for driving at least two drawing carriages, is characterized in that at least one of the drawing carriages is formed according to one of claims 1 to 7. The drive unit can have a main shaft that is driven during operation and rotates about a longitudinal axis and has at least one drive web that drives one of the drawing carriages in a translational movement parallel to the drawing direction, forming a drawing curve. Alternatively, the at least one drawing carriage on the drawing machine can also be driven in another way, e.g. with a linear motor.

[0021] The drive unit can be configured so that the position of the drawing carriage is unique for a given rotational position of the drive unit. For example, in the case of a drive unit with a rotating main shaft, the moment at which the torque motor moves the clamping jaws of the drawing carriage to open or close them can be determined from the rotational position of the main shaft, which can be determined, for example, via an angle sensor. Alternatively, the position of the drawing carriage can of course be monitored directly, for example, using optical or electrical sensors.

[0022] In the following, an advantageous embodiment of the drawing carriage and an exemplary embodiment of the drawing machine are illustrated by way of example using figures.

[0023] It shows Fig. 1: a drawing carriage with torque motor in perspective, Fig. 2: the drawing carriage according to Fig. 1 in side view, Fig. 3: in plan view a lower part of the drawing carriage according to Fig. 1 without top plate and clamping jaw movement device, Fig. 4: top view of a clamping jaw moving device, Fig. 5: the clamping jaw movement device in a lateral cross-section, Fig. 6 the clamping jaw movement device in front view, Fig. 7: a drawing machine known from the prior art in plan view.

[0024] A drawing machine known from the prior art according to EP 3 487 644 B1 is shown in plan view in Fig. 7. Two drawing carriages 1a and 1b are arranged on the drawing machine. Fig. 7 The right-hand, front drawing carriage 1a has a pulling clamp for the drawn material 2 (not clearly shown here), while the rear drawing carriage 1b comprises an inlet hopper 3 which facilitates the transfer of the front end of the drawn material 2 from the front drawing carriage 1a to the rear drawing carriage 1b. To drive the drawing carriages 1a and 1b parallel to the drawing direction, a main shaft 5 is rotated by means of a main shaft motor 4, e.g. an electric motor, and gear means not shown in detail here, on which main shaft 5 two drive webs 6 and 7 are arranged in a rotationally fixed manner. These would be invisible in the selected view, but are also shown here for better illustration. The main shaft 5 with the drive webs 6 and 7 serve as a drive unit for the drawing carriages 1a and 1b.

[0025] The drive webs 6 and 7 are each encompassed by one of the drawing slides 1a and 1b in such a way that the latter are forced into the desired translational back and forth movement when the main shaft 5 rotates.

[0026] For the wire drawing process, a wire is drawn at the front end of the drawing machine (in Fig. 7 right), the usually sharpened drawing material 2 is fed through a drawing die (not shown here) to the drawing-in gripper of the front drawing carriage 1a. Alignment motors 8 and 9 can be provided for the correct alignment of the drawing die. Subsequently, the main shaft 5 is rotated, forcing the drawing carriages 1a and 1b into a back-and-forth movement. The front drawing carriage 1a moves in Fig. 7 gripping the drawn material 2 with the pulling tongs, initially from right to left. Before the main shaft forces the front drawing carriage 1a back to the right, the pulling tongs open and the front drawing carriage 1a moves back to the right with the clamping jaws then opened (not shown in detail here), so that the front drawing carriage 1a can then also grasp the drawn material 2 with its clamping jaws. Alternatively, the pulling tongs can also be moved relative to the clamping jaws, e.g., by means of another motor (not shown here), until the clamping jaws can grasp the drawn material 2.

[0027] When the front drawing carriage 1a with the drawn product 2 between the clamping jaws then reaches its left position again, the drawn product is transferred to the second drawing carriage 1b, which executes a translational movement opposite to that of the drawing carriage 1a. For the transfer of the drawn product 2, the front drawing carriage 1a is therefore in its rearmost position, while the rear drawing carriage 1b is in its frontmost position. Therefore, exactly one of the two drawing carriages 1a or 1b with closed clamping jaws always pulls the drawn product 2 into Fig. 7 to the left while the other pulling carriage 1 a or 1b moves back to its front position with open clamping jaws.

[0028] The clamping jaws of the drawing carriages 1a and 1b according to the cited prior art are moved by means of linear motors 10 and 11, respectively.

[0029] Fig. 1 shows in perspective and Fig. 2 shows a side view of an embodiment of a drawing carriage 12 according to the invention. Such drawing carriages can be used, for example, on a drawing machine as shown in Fig. 7, can be used instead of the linear motor driven drawing carriages shown there. Fig. 1 to 6 corresponds in its function to the drawing carriage 1b of the prior art according to Fig. 7. Of course, a drawing carriage with the function of the drawing carriage 1a of the prior art can also be equipped in a corresponding manner with the clamping jaw displacement device (41) according to the invention, which is explained below.

[0030] In Fig. 2 downwardly projecting projections 13 and 14 are provided, which engage the associated drive web 7 of the wire drawing machine (see Fig. 7) and each having a rolling element 15 or 16 rolling on the drive web 7. Instead of the rolling elements 15 and 16, sliding elements or other guide elements are also conceivable.

[0031] In addition, the drawing carriage 12 has guide elements, here, for example, in the form of guide rollers 17 to 20, which serve to guide the drawing carriage on the frame of the drawing machine. Between an upper plate 21 and a lower plate 22 there is a space through which the wire 2 ( Fig. 7) during operation of the wire drawing machine and in which clamping jaws 23 and 24 are arranged. The clamping jaws 23 and 24 are more clearly visible in the top view of the lower plate 22, where they are in the closed state. Wedge elements 25 and 26, each supporting one of the clamping jaws 23 and 24, are guided along one of the ball tracks 27 and 28. The wire 2 ( Fig. 7) enters the intermediate space through an inlet funnel 35.

[0032] A torque motor 29 ensures, in a manner to be described later, a movement of a bridge 30 in the wire drawing direction. Engaging elements 31 and 32 are arranged on the bridge 30, each of which engages in a corresponding engagement slot 33 or 34 of the wedge elements 25 and 26, which are best positioned in Fig. 3. The torque motor 29, the bridge 30, and the engagement elements 31 and 32 are components of a clamping jaw movement device 41, which is used for the controlled movement of the clamping jaws 23, 24.

[0033] If the wedge elements 25 and 26 are connected by means of the bridge in Fig. 3 is moved to the left, the clamping jaws 23 and 24 open, whereby a wire 2 ( Fig. 7) is released. During the opposite movement back to the right, the wedge elements 25 and 26 and thus the clamping jaws 23 and 24 are closed in order to clamp any wire 2 that may be located therebetween.

[0034] The clamping jaw technology with wedge elements 25 and 26 guided on ball tracks 27 and 28 is known per se from the state of the art.

[0035] Fig. 4 shows the clamping jaw moving device 41 in plan view, the Fig. 5 in lateral cross-section and Fig. 6 in a front view. The bridge 30 and thus the wedge elements 25 and 26 are driven by the torque motor 29, which is located in the Fig. 4 and Fig. 5, via a drive shaft 36, which can be implemented, for example, with a threaded spindle. The torque motor 29 does not have its own motor shaft. Rather, the drive shaft 36 takes over the function of the motor shaft, for which purpose the drive shaft 36 is rigidly connected to the rotor 37, e.g., by screwing. The stator 38 of the torque motor 29 is rigidly connected to a housing part 39 of the drawing carriage 12.

[0036] The drive shaft 36 passes through a shaft bearing device 40 with bearing elements 42, e.g., tapered roller bearings, and reaches a transmission sleeve 44 belonging to a front part 43 of the clamping jaw displacement device 41, with which the movement of the drive shaft 36 is converted into a translational movement of the front part 43. In the case of a threaded spindle as the drive shaft 36, the transmission sleeve 44 can be, e.g., a recirculating ball sleeve.

[0037] The bridge 30 is mounted in the front part 43 of the clamping jaw displacement device 41 via elastic elements 45, here designed as disc springs, in such a way that it is movable parallel to the wire drawing direction to a small extent relative to the remaining front part 43 in order to counteract a movement of the wedge elements 25 and 26 occurring at the beginning of the wire drawing process carried out by the drawing carriage 12 (see e.g. Fig. 3). The movement of the wedge elements 25 and 26 is a result of the high forces occurring at the beginning of the drawing process with the wire 2 clamped between the clamping jaws (see Fig. 7).

[0038] The bridge 30 is guided on guide rails 46 and 47, e.g., with ball, roller, or plain bearings. The position of the bridge 30 on the guide rails 46 and 47 is detected by a position detection unit 48 arranged, for example, on the guide rail 47. A suitable integrated measuring system for ball and roller rail guides is available, for example, from Bosch Rexroth AG. List of reference symbols 1 pulling carriage 2 Drawn goods 3 entry funnels 4 Main shaft motor 5 Main shaft 6 Drive bridge 7 Drive bridge 8 Alignment motor 9 Alignment motor 10 linear motor 11 Linear motor 12 pulling carriages 13 projections 14 projections 15 rolling elements 16 rolling elements 17 Leadership role 18 Leadership role 19 Leadership role 20 Leadership role 21 upper plate 22 lower plate 23 clamping jaw 24 clamping jaw 25 wedge elements 26 wedge elements 27 Marble Run 28 marble run 29 Torque motor 30 Bridge 31 engagement element 32 engagement element 33 Access slot 34 access slot 35 entry funnels 36 Drive shaft 37 Rotor 38 Stator 39 Housing part 40 Shaft bearing device 41 Clamping jaw movement device 42 bearing element 43 front part 44 Transfer sleeve 45 Elastic element 46 Guide rail 47 Guide rail 48 Position detection unit

Claims

[1] Draw carriage for a drawing machine, comprising two clamping jaws (23, 24) and a clamping jaw movement device (41) for opening and closing the clamping jaws (23, 24), characterized by , that the clamping jaw movement device (41) has at least one torque motor (29), at least one drive shaft (36) which can be driven rotatorily by the at least one torque motor (29), a front part (43) which can be moved directly or indirectly via the drive shaft (36) and position sensing means (48), wherein the position sensing means (48) are arranged to detect the position of the front part (43) and / or the associated clamping jaws (23, 24) directly or indirectly. [2] Draw slide according to claim 1, characterized by , that the drive shaft (36) is supported by means of a shaft bearing arrangement (40), in particular comprising at least one tapered roller bearing. [3] Draw slide according to claim 1 or 2, characterized bya transmission element (44) that converts a rotational movement of the drive shaft (36) into a translational movement of the front part (43) of the clamping jaw moving device (41). [4] Draw slide according to claim 3, characterized by , that the transmission element (44) is a ball recirculation sleeve. [5] Draw slide according to claim 3 or 4, characterized by , that the front part (43) has a bridge element (30) for transmitting the translational movement of the front part (43) to the clamping jaws (23, 24), wherein the bridge element is elastically mounted in the front part (43). [6] Draw slide according to any one of the preceding claims, characterized by , that the front part (43) of the clamping jaw movement device (41) is guided on at least one linear guide aligned in the pulling direction. [7] Draw slide according to any one of the preceding claims, characterized bya drawing device (24), in particular a drawing pliers, for drawing a drawing material towards the clamping jaws (16), wherein the drawing device (24) preferably has a drawing linear motor for the drawing movement. [8] Draw slide according to any one of the preceding claims, characterized by an entry funnel (35) for a drawing material. [9] Drawing machine comprising a drive unit for driving at least two drawing carriages (1), characterized by , that at least one of the drawing carriages (1) is formed according to one of claims 1 to 7. [10] Drawing machine according to claim 9, characterized by , that the drive unit has at least one main shaft (5) driven in operation and rotating about a longitudinal axis with at least one drive web (6, 7) driving one of the drawing carriages (12) to a translational movement parallel to the drawing direction.

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