Field of the Invention

This invention relates to a device for turning an object, and more specifically concerns a turning device as set forth in the preamble to appended claim 1. The invention further relates to a cam guide mechanism intended for use in the turning device.

Background of the Invention

Various conveyors, packaging machines and the like are used for conveying and handling objects, and fre¬ quently require that the objects can be turned through a predetermined angle. The reason for this may be that the object is to be oriented in another direction and subse¬ quently be further conveyed by the same conveyor, or that the object is to be transferred to another conveyor and thus has to be turned through a predetermined angle, for instance an angle of 90°.

In both cases, the object at issue is frequently conveyed by some sort of conveyor, for instance a belt conveyor, up to a turning site or junction, where the object is momentarily stopped and first is lifted a cer¬ tain distance in the vertical direction by one and the same turning device so as to be released from the con¬ veyor and be supported by the turning device. The object is then turned through the predetermined angle and is finally lowered so as to rest on the conveyor in the turned position. Thus, the turning operation often involves a lifting operation.

US-3,100,039 teaches a conventional method of achieving the combined lifting and turning operation described above. The US document describes a turning device intended for use in association with a conveyor. This turning device comprises a turntable which, with the aid of a first pneumatic piston and cylinder unit, is movable in the vertical direction along an axis between a

lower position on a level with an adjoining conveyor belt and an upper position above the conveyor belt. Further¬ more, the turntable is, with the aid of a second pneuma¬ tic piston and cylinder unit, reciprocatingly turnable about the axis within a restricted angular range.

However, this prior-art construction suffers from a number of drawbacks. Thus, the linear lifting and lower¬ ing movement of the turntable, as well as the turning movement thereof, is brought about with the aid of various driving means. This constitutes a complicated solution, since the relative movements of the driving means thus have to be synchronised. In addition, the turning movements of the turntable are reciprocating, the forward movement actively causing an object to turn, whereas the backward movement merely returns the turn¬ table to a suitable position in view of a subsequent forward movement for turning the object. As a result, only every other turning movement of the turntable is an active movement, i.e. causes the supported object to turn. Also, this conventional construction is disadvan¬ tageous in that the mechanical components involved in the turning operation are subjected to a considerable load when heavy objects are to be lifted and turned.

There is thus a demand for a better solution than the one offered by the prior-art construction described above.

One object of the invention is to provide a device which is adapted to turn an object while the latter undergoes a linear reciprocating movement, especially in the vertical direction, and which obviates the drawbacks mentioned above.

Another object of the invention is to provide a turning device which is subjected to less torsional stress than prior-art devices.

Summary of the Invention

According to the invention, these and other objects are attained by a turning device having the distinctive features recited in appended claim 1, preferred embodi- ments of the turning device being defined in dependent claims 2-10.

The invention further provides a cam guide mechanism having the distinctive features recited in independent claim 11, preferred embodiments of the cam guide mecha- nism being defined in dependent claims 12-14.

The present invention has several advantages over the prior art. The fact that a single driving means, which may be of simple and conventional design, achieves not only the lifting and lowering movement but also the turning movement results in a construction which, gene¬ rally speaking, is less expensive than prior-art turning devices. In addition, the use of a single driving means of simple design increases the service life of the turn¬ ing device, since there are but a few mechanical compo- nents running the risk of being exposed to wear. Further¬ more, there is no need of synchronising several separate driving means during the turning cycle.

The inventive construction, in which the turning movement is achieved by converting a component of a linear force to a torsional force, further entails that the mechanical components involved in the turning opera¬ tion are not exposed to torsional stress of any signifi¬ cance. This means that the device is able to take up a greater load and that the component parts are not much worn.

The invention further enables the prior-art, inac¬ tive, backward turning movement to be dispensed with, since the turning movement according to the invention can be achieved continuously in the same direction. It should further be emphasised that the linear movement of the turning device and the cam guide mecha¬ nism according to the invention may be vertical, as will

be described below in connection with the preferred embo¬ diment of the invention, as well as non-vertical, for instance horizontal. Thus, the appended claims are meant to encompass all conceivable directions of the axis of movement of the device, and all references in the fore¬ going as well as in the following to a lifting and lower¬ ing movement, as well as to a movement in the vertical direction, are to be interpreted accordingly.

Brief Description of the Drawings

A preferred embodiment of the inventive turning device in the form of a turntable, as well as an inven¬ tive cam guide mechanism included therein, will now be described in more detail with reference to the accompany- ing drawings, in which

Fig. 1 is a side view of the turntable, which is disposed in a roller conveyor and shown when occupying a lower initial position,

Fig. 2 is a top view of the turntable and the con- veyor in Fig. 1,

Fig. 3 is a side view of a frame forming part of the turntable,

Fig. 4 is a top plan view of a jacket for the frame in Fig. 3 when in flat state, Fig. 5 is a section taken along the line A-A in Fig. 3,

Fig. 6 is a side view of a lifting piston forming part of the turntable,

Fig. 7 is a section taken along the line B-B in Fig. 6, and

Fig. 8 is a side view of a cam follower adapted to be mounted in the lifting piston shown in Fig. 6.

Description of a Preferred Embodiment In Figs 1 and 2, the turntable is disposed in a horizontal roller conveyor with rollers 100 mounted in a stand 110, the turntable being here adapted to turn some

sort of object, for instance a carton (not shown), about a vertical axis 1 through an angle of 90° in the direc¬ tion indicated by the arrow a.

As appears from Fig. 1, the turntable comprises a driving means in the form of a vertical piston and cylin¬ der unit 2 including a cylinder 3 and a piston rod 4 which is reciprocatingly movable along the axis 1, as well as freely turnable about the latter. The turntable further comprises a supporting means 5, which is intended to support the object and includes an elongate lifting piston 6, which is centred round and extends vertically along the axis 1 and which, at its lower end, is rigidly connected to the piston rod 4 by means of a screw joint 8. The supporting means 5 is thus vertically adjustable along the axis 1, as well as turnable about the latter.

It appears from Figs 6-8 that the lifting piston 6 at its lower end has four recesses 7, which are directed radial¬ ly inwards and each are adapted to accommodate a cam fol¬ lower 11 in the form of a roller bearing which, with its inner ring, is fastened by screws in the respective recesses 7.

The supporting means 5 further comprises two ortho¬ gonal supporting plates 12, 13 which, by the intermediary of a spacer 10, are connected to the upper end of the lifting piston 6 and which together form the shape of a cross perpendicular to the axis 1.

As appears from Fig. 1, the supporting plates 12, 13 are, in the initial position of the turntable, located on a level beneath the upper periphery of the rollers 100. It is further evident from Figs 1 and 3-5 that the turntable comprises a frame 16, which is stationary in relation to the stand 110 of the conveyor and which includes an elongate, cylindrical jacket 18, which is centred round and extends vertically along the axis 1 so as to surround essentially the entire lifting piston 6. The inside diameter of the jacket 18 corresponds to the diameter of the lifting piston 6. The jacket 18 is clamp-

ed in, and supported by, a supporting element 20 of the frame 16, this element being arranged above the piston and cylinder unit 2 and having an opening for receiving the latter. The jacket 18 is made up of two substantially identical parts, namely an upper part 22 and a lower part 24, which are rigidly interconnected with the aid of four vertical connecting rods 26.

The jacket parts 22, 24 are shown in flat state in Fig. 4, from which it appears that the jacket-part ends facing one another are provided with recesses in such a manner that there is formed, between the two jacket parts 22, 24, an undulated, throughgoing guiding groove 28 run¬ ning endlessly in the circumferential direction and being adapted to accommodate the cam followers 11. The guiding groove 28 has a width corresponding to, but being slight¬ ly larger than, the diameter of the cam followers 11.

The guiding groove 28 comprises vertical lower por¬ tions 30, forming the troughs of the guiding groove, and vertical upper portions 32, forming the crests of the guiding groove. A vertical axis 34 extends through each vertical portion 30, 32 and is horizontally centred therein.

Furthermore, the guiding groove 28 comprises upward¬ ly inclined portions 36, each having an upper cam surface 38, as well as downwardly inclined portions 40, each hav¬ ing a lower cam surface 42. Each upper cam surface 38 extends from a downwardly-directed narrow end 44, which consists of the transition between one of the downwardly inclined portions 40 and one of the upwardly inclined portions 36, to the point where the guiding groove 28 passes from the upwardly inclined portion 36 to an upper vertical portion 32. Each lower cam surface 42 extends from an upwardly-directed narrow end 46, which consists of the transition between one of the upwardly inclined portions 36 and one of the downwardly inclined portions 40, to the point where the guiding groove 28 passes from

the downwardly inclined portion 40 to a lower vertical portion 30.

Each downwardly-directed narrow end 44 and each upwardly-directed narrow end 46 are offset in the late- ral direction (to the left in Fig. 4) in relation to respective axes 34, i.e. in relation to the centre of respectively the lower and the upper vertical portions 30, 32 of the guiding groove 28.

The turntable operates as follows. In a lower ini- tial position, the piston rod 4 of the piston and cylin¬ der unit 2 occupies a retracted position, in which the supporting plates 12, 13 are located on a lower level than the upper periphery of the rollers 100, and in which each cam follower 11 occupies a starting position PI (shown in Fig. 4) and rests on the bottom of one of the lower vertical portions 30 of the groove 28, the cam fol¬ lower 11 thus taking up the dead weight of the supporting means 5.

Initially, the object to be turned is conveyed to a position above the supporting plates 12, 13 by means of the conveyor. The piston and cylinder unit 2 is then actuated, causing the piston rod 4 to perform a linear lifting movement along the axis 1. As a result of the upward linear movement of the piston rod 4, the lifting piston 6 is likewise moved upwards, each cam follower 11 received in the guiding groove 28 being, owing to this linear movement, caused to follow the lower vertical por¬ tion 30 of the groove 28 up to a lower intermediate posi¬ tion P2. Having reached this lower intermediate position P2, the cam follower 11 encounters the upper cam surface 38 and is thus forcibly applied against the latter as the lifting movement continues. The linear force generated by the piston and cylinder unit 2 is, as a result, partly converted to a torsional force, such that the piston rod 4 and the supporting means 5 will, in addition to the lifting movement, be subjected to a turning movement. The cam follower 11 travels in contact with the upper cam

surface 38 along the entire length thereof, up to an upper turning position P3, where the cam follower 11 is located in the upper vertical portion 32 of the guiding groove 28. In the turning position P3, the piston rod 4 and the supporting means 5 have, as seen in Fig. 2, been turned anticlockwise through a part angle of 45° in rela¬ tion to the starting position.

When the cam follower has reached the turning posi¬ tion P3, the supporting means 5 is thus completely up- lifted. As a result of a subsequent linear lowering move¬ ment of the piston rod 4, the cam follower 11 is moved vertically downwards from the turning position P3 to an upper intermediate position P4, where the cam follower 11 instead encounters the lower cam surface 42. As the lowering movement continues, the cam follower 11 travels in contact with the lower cam surface 42 along the entire length thereof to a lower intermediate position P5, the supporting means 5 and the piston rod 4 being thus com¬ pelled to turn anticlockwise, as seen in Fig. 2, through a second part angle of 45°. Finally, the supporting means 5 is lowered in the vertical direction without turning, such that the cam follower 11 reaches an end position P6, which corresponds to the starting position PI, the only difference being that the end position P6 is located in a successive trough of the guiding groove 28, as compared with the trough where the starting position PI is locat¬ ed. The supporting plates 12, 13 will thus again be located on a level beneath the upper periphery of the rollers 100, thus releasing the object from the support- ing plates. The piston and cylinder unit 2 has thus com¬ pleted a cycle consisting of a lifting and a lowering movement, while the supporting means 5 simultaneously has been turned through 90°. It will be appreciated that the end position P6 constitutes the starting position PI of the subsequent cycle of movement.

Owing to the special design of the groove with lower and upper narrow ends 44, 46 offset in the lateral direc-

tion in relation to the axis 34, the cam follower 11 will be brought into direct application against the respective upper and lower cam surfaces 38, 42.

Thus, the object to be turned is first located on the supporting rollers 100 above the turntable at a dis¬ tance therefrom. When the driving means 2 is actuated, the object is first lifted a small distance, such that the supporting plates 12, 13 come to occupy a level above the upper periphery of the rollers 100 in order not to be interfered with during the subsequent turning movement.

As the lifting movement continues, the object is gradual¬ ly turned through 45° in a predetermined direction. Then, the driving means 2 is actuated in the opposite direc¬ tion, such that the object is lowered and thus simulta- neously is turned through another 45° in the same direc¬ tion. Finally, the turntable is lowered beneath the sup¬ porting rollers 100, and the object thus turned through 90° again rests on the supporting rollers to be further conveyed thereby. It will be appreciated that all the cam followers 11 simultaneously perform a corresponding movement in their respective parts of the endless undulated guiding groove 28. It is also to be understood that the supporting means will be turned through another 90° in the same direction during the subsequent cycle of movement of the piston and cylinder unit 2.

Conceivable Modifications of the Invention

It goes without saying that the invention is by no means restricted to the preferred embodiment described above, but can be modified in many ways within the scope of the appended claims. For instance, the vertical por¬ tions 30 and/or the vertical portions 32 may be dispensed with. Also, the inclined portions need not be straight but may, for example, have the shape of half a parabola. In addition, the jacket parts 22, 24 may be mutually turnable about the axis 1, thus enabling turning in both

directions. There may be provided one cam follower 11 only. Moreover, the guiding groove 28 and the cam fol¬ lowers 11 may change places, i.e. the guiding groove 28 may be provided in the lifting piston 6, while the cam followers 11 are stationarily supported by the frame 16. Finally, it should once more be emphasised that the use of the turning device need not be focused on the vertical direction, for which reason the expressions "up" and "down" as well as "upper" and "lower" throughout are to be interpreted in the broad sense, as referring to oppo¬ site directions in relation to the orientation of the main axis.