US20040064931A1

US20040064931A1 - Screwing station

Info

Publication number: US20040064931A1
Application number: US10/467,218
Authority: US
Inventors: Elmar Albrecht; Markus Schleier; Gottfried Seeberger; Rudolf Plachta; Holger Maier; Jurgen Reddig
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2001-02-09
Filing date: 2002-02-05
Publication date: 2004-04-08
Also published as: EP1358039B1; DE10106037A1; DE50201354D1; WO2002064306A1; EP1358039A1; BR0207111A

Abstract

The invention relates to a screwing station (2) in which transmission housings (4) are screwed together. Said screwing station is provided with a connecting plate (8) that is detachably linked with the transmission housing (4). A first guide (10) is disposed on the connecting plate (8), along which guide a second guide (12) can be displaced relative to the connecting plate on a first axis (14). On the second guide (12) a third guide (16) is disposed which can be displaced relative to the connecting plate (8) along a second axis (18) that is at a right angle to the first axis (14), thereby allowing a screw driver (20) a displacement relative to the connecting plate (8) along a third axis (22) that is at a right angle to the second axis (18).

Description

The invention concerns a screw pickup for the automated screw assembly of gearboxes according to the principal clause of claim 1.

Industrially manufactured gear boxes are put together in production lines, out of a plurality of individual components. In the final stage of assembly of the gears, the housing screw connections, of which there are a large number, are brought to a predetermined degree of clamping torque; this process, generally speaking, is supposed to guarantee a structure which is watertight and free of distortion. When putting together the individual housing parts of a multi-directional control gear, especially for commercial vehicles, it is frequently necessary to introduce and tighten more than 30 screw connections. In industrial practice, the screw connections are either tightened by hand individually or through the use of individual screw-driving machines mounted on cross-beams, which can tighten a screw connection arranged in a fixed, predetermined position on the gear box.

In view of the rigid positioning of the screw-driving machine relative to the position of the screw connection, it is necessary, in practical terms, to provide a separate screw-driving machine for each screw connection; this, in turn, presents a considerable cost factor. The number of screw-driving machines to be mounted on a cross-beam is limited by spatial considerations so that when the arrangement of the screw connections is changed, a new cross-beam must be installed.

Manually operated screw-driving machines are known, for example, from DE 19846947 which also specifies a monitoring of the screwing process.

The invention is based on the task of creating a process-secure device for the screw assembly of gear box.

The task is solved by a screw pickup with the characteristics of claim 1. Designs thereof constitute the objects of dependent claims.

According to the invention, a screw pickup for the screw assembly of gear boxes is proposed, involving the provision of a connection plate, which is detachably connected to the gear box. A first track is arranged on the connection plate along which, on a first axis, a second track can be moved relative to the connection plate. A third track is arranged on the second track, which can be moved relative to the connection plate along a second axis which runs perpendicular to the first axis, and which enables a screw-driving machine to be moved relative to the connection plate along a third axis which extends perpendicular to the second axis, so that the screw-driving machine reaches the screw connection to be tightened.

In one design, the third track can be moved relative to the connection plate along the third axis and, in another design, the screw-driving machine can be moved relative to the connection plate on the third track along the third axis. Another design has tracks each of which is driven by an electric motor. In yet another design, the electric motors of the tracks and the screw-driving machines are actuated by a control device which is integrated into the screw pickup. In another design, the control device is programmable in such a way that, in predetermined positions, the screw connections are actuated by the screw-driving machine, and are tightened to a predetermined degree of torque. In still another design, the tracks are located within a protective device and the screw-driving machine simply moves within this protective device through which, in another design, it is possible to obtain access thereto. Preferably, the screw-driving machine maintains a constant axis of rotation during actuation of the various screw connections of the gear box. In one design, the screw-driving machine used is an electrically operated screw-driving machine; in another design, it is a pneumatically operated screw-driving machine whereby the electric motors of the tracks and the air supply of the pneumatically operated screw-driving machine can also be controlled by the control device which is integrated into the screw pickup.

The screw-driving machine used, for example, is a screw-driving machine of a type customarily found in the trade whose torque is adjustable and which includes monitoring of the torque. Such a screw-driving machine can register the revolutions implemented during a screwing process and its speed of rotation is continuously adjustable. The tracks, for example, are constructed through the use of highly precise linear units with AC servo motors, incremental rotary pulse transmitters, limit switches and brakes.

The position of each screw required and the required degree of clamping torque are programmed, in advance, into the control device by the fitter of the screw pickup. To this end, the fitter can either program the position by means of a coordinate system relative to the connection plate or manually displace the screw-driving machine to the desired position while allowing the control device, by means of this manual displacement, to “learn” the correct position. For this purpose, the fitter can have access to the internal workings of the protective device in order to reach the screw-driving machine. The positions installed for a certain type of gear are always the same. This is ensured by the connection plate used for the respective gear type, which is always fastened to the same location on the respective gear box. At the time of operation, the screws are inserted into the threaded holes in the gear box and the screw pickup is set in operation. The screw-driving machine successively moves to each of the various screw connections, tightens the respective screw connection and moves on to the next one. After all of the screw connections have been completely handled, a suitable message concerning the completion of the process is sent to the operator—for example, by means of a colored signal lamp. If, in the course of operation, any screw connection is recognized not to be in good order—for example, because the requisite torque cannot be achieved, or because the number of revolutions implemented is recognized as insufficient, this malfunction is similarly brought to the attention of the operator and, following a suitable acknowledgment, the screw connection in question is again loosened. The screw pickup then automatically proceeds to the next screw connection. Following the completion of all screw connections and the sending of a suitable message, the operator can determine which screw connections must be checked by observing which screw connections have not been tightened and, if necessary, tighten it manually.

The invention is explained in greater detail by means of a drawing.[0011]
The drawing shows a [0012] screw pickup 2 which is set in place on a gear box 4.
The gear box itself is mounted on a [0013] mobile assembly cart 6, by which it is transported in a process chain in the area of the screw pickup 2. The gear box 4 is rotatably mounted on the assembly cart 6 so that it can be rotated by an operator into such a position as to enable a connection plate 8 to be detachably fastened to the gear box 4—for example, to be tightly clamped thereto by means of suitable clamping devices (not shown). A first track 10 is rigidly fastened to the connection plate 8. A second track 12, which can be moved relative to the connection plate 8 along a first axis 14 of the first track 10 is provided on the first track 10 at right angles thereto. A third track 16, which can be moved relative to the connection plate 8 along a second axis 18 of the second track 12 is provided on the second track 12 at right angles thereto. A screw-driving machine 20 is fastened to the third track 16, which can be moved relative to the connection plate 8 along a third axis 22 of the third track 16. Alternatively, the third track 16 can also be arranged on the second track 12 in such a way that the third track 16 is itself moved along the third axis 22. By means of this arrangement of the screw-driving machine 20, which is displaceable in three directions, the screw-driving machine 20 can reach all of the screw connections of the gear box which lie within the course of displacement of the third track 16 along the axis 22. In this way, the axis of rotation of the screw-driving machine 20 is kept constant. A protective frame 24 is provided on the first track 10, which surrounds all of the tracks 10, 12, 16 and the screw-driving machine 20, so that the operator cannot be injured during the course of the automatic displacement of the screw-driving machine 20. An electronic control device 26 is also provided on the track 10, which is in connection with the screw-driving machine and the tracks 10, 12, 16 and controls them.
The proposed [0014] screw pickup 2 enables the automated assembly of a gear box 4 by means of a pneumatically or electrically operated screw-driving machine 20 for any desired number of screw connections. During the pulse time of the screwing processes performed for one gear box 4, the operator of the screw pickup 2 can undertake additional activities. The space required for the screw pickup 2 is small and only slightly larger than the gear box 4 itself. This space requirement, however, cannot compare to, and is significantly less than, the space requirement for an industrial robot; moreover, the costs involved in both of these types of systems are extremely different. The screw pickup 2 is easy to operate and the handling thereof can quickly be learned by trained operator.

Reference Numbers

[0015] 2 Screw pickup
[0016] 4 Gearbox
[0017] 6 Assembly cart
[0018] 8 Connection plate
[0019] 10 First track
[0020] 12 Second track
[0021] 14 First axis
[0022] 16 Third track
[0023] 18 Second axis
[0024] 20 Screw-driving machine
[0025] 22 Third axis
[0026] 24 Protective frame
[0027] 26 Control device

Claims

1. Screw pickup (2) for the screw assembly of gear boxes (4), characterized in that a connection plate (8) is provided which is detachably connected to the gear box (4), and on which a first track (10) is provided, on which, along a first axis (14), a second track (12) can be moved relative to the connection plate (8), and wherein, on said second track (12), a third track (16) is provided, which can be moved relative to the connection plate (8) along a second axis (18) perpendicular to the first axis (14), and which enables a screw-driving machine (20) to be moved relative to the connection plate (8) along a third axis (22) perpendicular to the second axis (18).

2. Screw pickup (2) according to claim 1, characterized in that the third track (16) can be moved relative to the connection plate (8) along the third axis (22).

3. Screw pickup (2) according to claim 1, characterized in that the screw-driving machine (20) can be moved relative to the connection plate (8) along the third axis (22) on the third track (16).

4. Screw pickup (2) according to any of claims 1 to 3, characterized in that the tracks (10, 12, 16) are each driven by an electrical motor.

5. Screw pickup (2) according to claim 4, characterized in that the electrical motors of the tracks (10, 12, 16) and of the screw-driving machine (20) are actuated by a control device (26), which is integrated into the screw pickup (2).

6. Screw pickup (2) according to claim 5, characterized in that the control device (26) can be programmed in such a way that, in predetermined positions, the screw connections are actuated by the screw-driving machine (20), and are tightened to a predetermined degree of torque.

7. Screw pickup (2) according to any of claims 1 to 6, characterized in that the tracks (10, 12, 16) are located within a protective device (24) and the screw-driving machine (20) is simply moved within the protective device (24).

8. Screw pickup (2) according to claim 7, characterized in that access to the internal workings of the protective device (24) is possible.

9. Screw pickup (2) according to any of claims 1 to 8, characterized in that the screw-driving machine (20) maintains a constant axis of rotation during the actuation of the various screw connections of the gear box (4).

10. Screw pickup (2) according to any of claims 1 to 9, characterized in that the screw-driving machine (20) is an electrically operated screw-driving machine.

11. Screw pickup (2) according to any of claims 1 to 9, characterized in that the screw-driving machine (20) is a pneumatically operated screw-driving machine.

12. Screw pickup (2) according to claim 11, characterized in that the electric motors of the tracks (10, 12, 16) and the air supply of the pneumatically operated screw-driving machine (20) are actuated by the control device (26) which is integrated within the screw pickup (2).

13. Process for the assembly of gear boxes (4) characterized in that, in a screw pickup (2) which is detachably fastened to the gear box (4) by means of the connection plate (8), by means of a screw-driving machine (20) which can be moved in three directions, various positions of screw connections of the gear box (4), which have been programmed prior to assembly, are accessed and tightened to a predetermined torque.