DRAWBENCH

Abstract

A draw bench has a draw bed (1), with a die block (2) defining a draw axis (11), with a draw carriage (3) movable along the draw bed (1) and aligned with respect to the draw axis (11), and with at least two racks (5) arranged fixedly on the draw bed (1) and extending in the direction of the draw axis (11), which racks mesh with drivable drive gears (7, 8) provided in the draw carriage (3). The toothing (6) of the racks (5) are provided on sides of the racks (5) facing towards or away from each other, the line of action of the resulting tangential components (Ft) of the tooth forces (F) coincides with the draw axis (11) and the torques caused by the radial components (Fr) of the tooth forces (F) in the region of the two racks (5) and acting on the draw carriage (3) in opposite directions cancel each other out.

Description

TECHNICAL FIELD

The invention relates to a draw bench with a draw bed, with a die block defining a draw axis, with a draw carriage movable along the draw bed and aligned with respect to the draw axis, and with at least two racks arranged fixedly on the draw bed and extending in the direction of the draw axis, which racks mesh with drivable drive gears provided in the draw carriage.

STATE OF THE ART

In order to avoid the disadvantages caused by the necessity of a continuous draw carriage guide and the arrangement of a heavy drive motor on the draw carriage in the case of draw benches which have draw carriages guided along the draw bed with drive gear wheels driven by a motor and drive gear wheels arranged in a fixed position in the draw bed, racks meshing with the drive gears, it is known (DE 1 819 329 U1) to dispense with a draw carriage and to provide the rack, which is movably mounted on rollers of the draw bed, with a coupling device for the material to be drawn. The rack is driven by a drive motor provided in the draw bed, which drives a drive gear meshing with the rack with a horizontal axis of rotation by means of a gearbox. The arrangement is such that the power transmission between the drive gear engaging from below in the toothing of the gear rack provided on the underside of the gear rack and the gear rack lies in a plane that accommodates the draw axis in order to be able to transmit the draw force in the direction of the draw axis. The main disadvantage is the space required for the movement of the rack in the draw direction, which corresponds to twice the draw length.

DESCRIPTION OF THE INVENTION

The invention is thus based on the task of designing a draw bench with a draw carriage which can be moved along a draw bed and a rack drive comprising racks arranged in the draw bed and drive gears in the draw carriage which mesh with these racks in such a way that the draw carriage is not subjected to any load-dependent torques which have a detrimental effect on the draw result.

Based on a draw bench of the type described at the beginning, the invention solves the problem set by the fact that the toothing of the racks is provided on sides of the racks which face towards or away from each other, that the line of action of the resulting tangential components of the tooth forces coincides with the draw axis and that the torques caused by the radial components of the tooth forces in the region of the two racks and acting on the draw carriage in opposite directions cancel each other out.

The tooth forces acting in the direction of the meshing line between the driven drive gears and the gear racks can be broken down into a tangential component running in the circumferential direction of the drive gear, i.e. tangential to the pitch circle, and a radial component perpendicular to it, which makes no contribution to the pulling force. The tangential components of the tooth forces produce a resulting tangential force with a line of action which, according to the invention, should lie in the draw axis of the draw bench, so that the tangential components of the effective tooth forces do not produce any drive-related torques on the draw carriage which would have to be absorbed by the draw carriage without deformation, which results in comparatively simple design conditions for the draw carriage without having to fear negative influences on the draw process.

However, the radial components of the tooth forces also cause torque loads on the draw carriage that cannot be neglected without further ado. To take these radial components into account, the toothing of the gear racks on the sides of the gear racks facing each other or facing away from each other is provided as a prerequisite for opposing radial components of the tooth forces in the area of the two gear racks. Since the geometric design conditions can always be selected for given drive torques in such a way that the torques caused by the radial components of the tooth forces in the area of the two racks and acting on the draw carriage in opposite directions cancel each other out, a rack and pinion drive is made possible for the draw carriage, which makes the draw carriage largely independent of load-dependent torques. Any load-independent weight torques can easily be taken into account in the design.

To ensure that the rack drive works in accordance with the invention, at least one driven gearwheel must be provided for each of the two racks. However, more advantageous design conditions result if the racks are meshed with two drive gears mounted in the draw carriage, because in this case smaller drive units result, especially if the drive gears are each driven by a gear motor. In addition, the draw carriage can also be driven using only one pair of drive gears if required.

If the gear racks are arranged in a plane inclined about the draw axis, it is possible to ensure simple removal of the drawn material from the draw bed.

BRIEF DESCRIPTION OF THE INVENTION

In the drawing, the object of the invention is shown, for example. It shows

FIG. 1 a draw bench according to the invention in a simplified plan view,

FIG. 2 a sectional view of this draw bench according to line II-II of FIG. 1 on a larger scale,

FIG. 3 a section according to line III-III of FIG. 2,

FIG. 4 a representation of a design variant corresponding to FIG. 3 and

FIG. 5 a representation of a further design variant corresponding to FIG. 2.

WAYS OF CARRYING OUT THE INVENTION

A draw bench according to the invention has a draw bed 1 with a die block 2 for corresponding draw tools and a draw carriage 3, which can be moved along the draw bed 1 on guides 4. To drive the draw carriage 3, a rack drive is provided with two racks 5 arranged in a fixed position on the draw bed 1 and usually composed of individual rack sections, which form a toothing 6 on their sides facing each other or facing away from each other. Drive gears 7, 8 mesh with the toothing 6 of the two toothed racks 5, which are rotatably mounted in the draw carriage 3 and preferably driven individually via a geared motor 9, so that the draw material 10 gripped by the draw carriage 3 can be drawn through the draw tool inserted in the die block 2. The die block 2 specifies the draw axis 11 for the draw tools used, whereby for a multi-strand draw bench the arrangement of the draw tools for the individual strands is selected so that the resulting draw force from the draw forces for the individual draw tools coincides with the draw axis 11 specified by the die block 2.

As can be seen from FIG. 3, the tooth force F acting on the teeth of the drive gears 7, 8 in the direction of the line of engagement of the teeth of the drive gears 7, 8 and the toothing 6 of the racks 5 can be broken down into a tangential component F_t and a radial component F_r perpendicular to it, which makes no contribution to providing the necessary draw force. The tangential components F_t acting in the longitudinal direction of the racks 5, in conjunction with the pull-through resistance of the drawn material 10 acting in the direction of the draw axis 11, cause load-related torques on the draw carriage 3, which should cancel each other out. For this reason, the arrangement is such that the line of action of the resulting tangential components F_t of the tooth forces F coincides with the draw axis 11.

If the drive gears 7, 8 are symmetrically opposite each other with respect to the draw axis 11, the torques on the draw carriage 3 caused by the tangential components F_t of the tooth forces F cancel each other out, provided that the matching drive gears 7, 8 are driven with the same torques. In the case of unequal torques and thus unequal tangential components F_t of the tooth forces F in the area of the two racks 5, the line of action of the resulting tangential components F_t shifts out of the center between the two racks 5 in inverse proportion to the ratio of the sums of the tangential components F_t acting on the two racks 5, which means that in such a case the draw axis 11 cannot run symmetrically to the two racks 5.

The same applies to the torques caused by the radial components F_r of the tooth forces F. With the symmetrical arrangement of the drive gears 7, 8 in relation to the draw axis 11 as shown in FIG. 3, it is obvious that the torques on the draw carriage 3 caused by the radial components F_r cancel each other out. If the drive gears 7 have a different mutual distance compared to the drive gears 8, as indicated in FIG. 4, the drive gears 7, 8 must be arranged symmetrically in relation to a plane of symmetry perpendicular to the draw axis 11 under otherwise identical drive conditions. Such a staggered arrangement of the drive gears 7, 8 of the two racks 5 can be advantageous, for example, with regard to the available space. If the toothing 6 of the racks 5 is not provided on the sides of the racks 5 facing each other, but on the sides facing away from each other, as shown in FIG. 4, other spacing ratios for the drive gears can be maintained, but there are no fundamental changes with regard to torque compensation, because the torques resulting from the radial components F_r of the tooth forces F in the area of one rack 5 cancel each other out with the torques of the radial components F_r of the tooth forces F in the area of the opposite rack 5.

This also applies to an arrangement as shown in FIG. 5, in which the racks 5 are arranged in a plane 12 that is inclined relative to a horizontal plane about the draw axis 11. This arrangement, which results in a different height position of the racks 5, can be helpful for the lateral discharge of the draw material 10 from the draw bench.

Claims

1. A draw bench comprising: a draw bed with a die block defining a draw axis;a draw carriage movable along the draw bed and aligned with respect to the draw axis, and having at least two racks arranged in a fixed position on the draw bed and extending in a direction of the draw axis;wherein the racks mesh with drivable drive gears provided in the draw carriage;wherein the racks have toothing provided on sides of the racks that face towards or away from each other;wherein tooth forces are formed by the drive gears engaged with the toothing, and a line of action of tangential components of the tooth forces coincides with the draw axis; andwherein torques caused by radial components of the tooth forces in a region of the two racks and acting on the draw carriage in opposite directions cancel each other out.

2. The draw bench according to claim 1, wherein the racks each mesh with two of the drivable drive gears mounted in the draw carriage.

3. The draw bench according to claim 1, wherein the drive gears can are each be driven by a gear motor.

4. The draw bench according to claim 1, wherein the racks are arranged in a plane inclined about the draw axis.

5. The draw bench according to claim 2, wherein the drive gears are each be driven by a gear motor.

6. The draw bench according to claim 5, wherein the racks are arranged in a plane inclined about the draw axis.

7. The draw bench according to claim 2, wherein the racks are arranged in a plane inclined about the draw axis.

8. The draw bench according to claim 3, wherein the racks are arranged in a plane inclined about the draw axis.