GB2227784A - A linear movement performing device - Google Patents

Description

A linear movement performing device This invention relates to a linear movement performing device, which comprises an elongate structure provided with two parallel, rectilinear guide surfaces which face opposite directions, a carriage movable along the structure and having at least three wheels for enlargement with the guide surfaces, and an adjusting means on the carriage for adjusting at least one of said wheels relative to the guide surfaces to, thereby, adjust the play between the carriage and the structure. The adjusting means comprises one or more rotatable discs on which said at least one of the wheels is journal led, and a lock means for locking each of said one or more discs against rotation as a desired play is set.

A previously known means for accomplishing a proper locking of the wheel carriers in a similar device is described in U.S. Patent No.

2,919,957 and comprises two mounting screws penetrating arcuate slots in a flange of each wheel carrier. When tightened, these mounting screws clamp the flange against the structure, thereby locking by friction the wheel carrier against rotation. The wheel carriers are also locked against rotation by two tangentially located adjusting screws.

The main object of the invention is to accomplish a linear movement performing device having an improved wheel carrier locking means which is simpler in design as well as in operation than prior art devices.

A preferred embodiment of the invention is described below with reference to the accompanying drawings.

On the drawings: Fig 1 shows, partly in section, a side view of a device according to the invention.

Fig 2 shows a top view of the device in Fig 1, with a part of the load connection plate removed.

Fig 3 shows a crosss section through the guide structure and the carriage.

Fig 4 shows a bottom view of the carriage, exposing the wheel adjusting means.

The device shown in the drawing figures comprises an elongate guide structure 10 and a carriage 11 movably guided thereon. The structure 10 consists of an extruded light alloy profile which includes a central cylinder bore 12, two parallel legs 13, 14 and two steel rods 15, 16 mounted in two opposite gw ses 17, 18 in the legs 13, 14. These steel rods 15, 16 provide twc parallel semi-cylindrical guide surfaces which "face" one another.

Alternatively, the steel rods 15, 16 may be mounted in two likewise opposite but outwardly directed grooves 20, 21 in the profile legs 13, 14.

The guide structure 10 also comprises undercut grooves 22, 23 of T-shape on its sides for mounting purposes.

The cylinder bore 12 forms the cylinder of a pneumatic piston-cylinder unit which also comprises a piston 25, two end covers 26, 27, two bands 28 (one only is shown in Fig 1) coupling the piston 25 to the carriage 11, and two pulleys 29 (cne only is shown in Fig 1) for the bands 28. Apart from a damping tube 31 extending from the end cover 26 and a corresponding bore 32 in the piston 25, no air communication means of the piston-cylinder unit are shown.

The carriage 11 comprises four wheels 33-36 which are mounted in pairs on two rotatable discs 37, 38. See Fig 4. Each wheel has a circumferential groove for engagement with the cylindrical guide surfaces of the steel rods 15, 16. For accomplishing an adjustability of the play between the carriage 11 and the guide structure 10, the wheels 33-36 are mounted on the discs 37, 38 in such a way that the overall dimension of the wheels, i.e. the largest distance between the utmost parts of the wheels exceeds the distance between the guide surfaces of the steel rods 15, 16. This means that by rotation of the discs 37, 38, the wheels 33-36 may be adjusted in relation to the guide surfaces.

As being illustrated in Fig 3, each wheel carrying disc 38 has a conically shaped portion 39 and being arranged to frictionally engage wedge portions 40, 41 on the carriage 11. Contact pressure between the disc 38 and portions 40, 41 is accomplished by a clamping disc 42 disposed concentrically relative to the disc 38 and arranged to engage the opposite (top) sides of the wedge portions 40, 41. By means of lock screws 43, 44 (see Figs 1 and 2) the wheel carrying disc 38 and the clamping disc 42 are forced towards each other to, thereby, obtain a friction lock between the disc 38 and the wedge portions 40, 41 cn the carriage 11.

For adjusting purposes, the disc 38 is formed with a central hexagon hole 46 to be engaged by an adjusting tool, for instance hexagon wrench.

As being shown in Fig 2, the disc 38 is formed with dent 47 at its periphery, which forms a point of support for a back up screw 48.

On top of the carriage 11 there is a coupling plate 49 by which the carriage 11 is connectable to external loads and objects to be moved by the device.

When setting the play between the carrige 11 and the guide structure 10, the lock screws 43, 44 on the clamping discs 42 are slackened to such an extent that the frictional lock between the wheel carrying discs 37, 38 and the wedge portions 40, 41 is substantially reduced. Hexagon wrenches are inserted in the central holes 46 of the discs 37, 38, and the latters are rotated simultaneously until a desired play is achieved. Then, the lock screws 43, 44 are tightened such that the discs 37, 38 are clamped against the wedge portions 40, 41 and, thereby locked against further movement.

As a safety measure, the back up screws 48 are adjusted in relation to the dents 47 so as to form a positive lock against a play increasing rotation of the discs 37, 38. Should the friction lock between the discs 37, 38 and the wedge portions 40, 41 for some reason become insufficient to withstand the forces transferred from the carriage 11 to the guide structure 10, there would be a risk not only that the play would be undesirably large but even that the carriage wheels 33-36 completely loose their engagement with the guide surfaces 15, 16.

By arranging the wheels 33-36 in pairs on two rotatable discs 37, 38, there is attained a simple adjusting means which provides for a wide wheel adjusting range.

It is to be understood, though, that the invention is not limited to the four wheel example described above, but may include a three wheel arrangment in which two non-adjustable wheels run against one of the guide surfaces, whereas the third wheel runs against the opposite guide surface and is adjustably supported on a rotating disc as described above.

According to another example based on the invention, the steel rod guides 15, 16 are mounted in the outside grooves 20, 21 on the structure profile, and the wheels are arranged so as to adjustably engage the steel rod guide surfaces from the outside. In this case too, the wheels could be arranged in a two-to-one disposition as described above or in a four wheel, pair wise disposition with all four wheels adjustably supported.

It is important to note that the embodiments of the invention are not limited to combinations including various types of piston-cylinder devices as in the above described example.

Claims (7)

1. Linear movement performing device, comprising an elongate structure provided with two parallel, rectilinear guide surfaces which face opposite directions, a carriage movable along said structure and having at least three wheels for cooperation with said guide surfaces, an adjusting means on said carriage for adjusting at least one of said wheels relative to said guide surfaces to, thereby, set the play between said carriage and said structure, said adjusting means comprises one or more rotatable discs on which said at least one of said wheels is journalled, and a lock means for locking each of said one or more discs against rotation as a desired play is set, wherein said lock means comprises wedge portions on said carriage and a clamping means for frictional locking of said one or more discs after setting of said play by clamping said one or more discs against said wedge means.

2. Device according to claim 1, wherein each of said discs comprises a conically shaped portion for frictional engagement with said wedge portions on said carriage.

3. Device according to any one of claims 1 or 2, wherein each of said one or more discs comprises a connection means for engagement of a disc rotating tool.

4. Device according to any one of claims 1-3, wherein an adjustable safety stop is arranged to positively back up the setting of each of said one or more discs.

5. Device according to any one of claims 1-4, wherein said elongate structure comprises the cylinder of a piston-cylinder unit, and a coupling means being arranged to connect the piston of said piston-cylinder unit with said carriage.

6. Device according to claim 5, wherein said coupling means comprises at least one band attached at its one end to the piston of said piston-cylinder unit and at its other end to said carriage.

7. Linear movement performing device, constructed and arranged substantially as hereinbefore described with reference to and as shown in the drawings.