GB2034828A

GB2034828A - Prevention of destruction of machine elements

Info

Publication number: GB2034828A
Application number: GB7934415A
Authority: GB
Original assignee: Polygraph Leipzig Kombinat Veb
Current assignee: Polygraph Leipzig Kombinat Veb
Priority date: 1978-11-09
Filing date: 1979-10-04
Publication date: 1980-06-11
Also published as: SU1036573A1; DE2941690A1; SE7909214L; FR2441125A1; DD139553A1

Abstract

A method of preventing the destruction of machine elements and a machine provided with means for such prevention is particularly applicable to shafts of printing machines, rotary folders and so forth. Precautions are to be taken against the destruction of machine elements especially in the case of breakdowns. In order that repairs can be avoided and machine standstill times reduced, the machine is stopped at the onset of overloading of the machine elements without the product processed by the machine having to be observed optically or by similar means. Overloading is measured at a region of a bearing (7), the measurement result detected, compared with a predetermined value and a signal for stopping the machine is triggered on a given tolerance being exceeded. Deformable spacer members (8) are arranged between a wall bore of the machine and the bearing (7) and a measurement value pick-up (14) (electrical fine indicator), which is connected with a motor switch (19), is arranged in a spacer member (8') disposed in the direction of loading. The invention is applicable not only to shaft bearings of printing machines, but generally in machine construction. <IMAGE>

Description

SPECIFICATION Prevention of destruction of machine elements The present invention relates to the prevention of destruction of machine elements.

In order to protect machine elements, for example in rotary folding machines, from damage or destruction due for instance to overload, various proposals have been put forward. CHOPS 542,056 discloses safety devices by which any irregularities are optically observed. Since light reflecting devices, which previously were used for this purpose, have substantial disadvantages, it has been proposed that at specific points of rotary folding machines, for example in a region of the folding blade cylinder wall covered over by the folded product, that an opening should be provided, through which when the folded product is absent a light conducting member receives an impulse from a light source disposed above the folding cylinder, which pulse can then be conducted away and utilized for stopping the machine.A disadvantage of these devices is that it is only if the sheet or product is absent that conclusions can be drawn about material accumulating at other points, whereas at the point at which the overload actually occurs, for example due to a material accumulation, no reaction takes place. If, for instance, in the aforementioned device the folded product is not absent but instead several folded products accumulate at this point, the folding blade cylinder and the folding knife cylinder could be damaged without this having been previously optically detected.

US-PS 1,784,757 discloses a method in which accumulations of products are deflected by a rake-shaped gate disposed near to the cutting and folding knife cylinder. This, however, does not result in success, since it is just the jamming of products etc. between the cylinder and the deflecting element when the machines are running at high speed, that can lead to destruction or at least to very long periods of machine shutdown. Also so-called overload couplings, such as sheet couplings, are no longer reliable nor sufficiently sensitive for plant units of increased output rating.

According to the present invention there is provided a method of preventing destruction of machine elements supported by bearing means, comprising the steps of detecting deformation of deformable means disposed at the region of the bearing means and, on the deformation exceeding a predetermined extent, generating a signal to actuate means to stop the machine.

The step of detecting deformation of the deformable means may comprise use of a fine tolerance indicator, the indication of which is compared with a reference value to form a difference which when exceeding a predetermined amount corresponding to said predetermined extent causes amplified signals to be generated to actuate the means to stop the machine.

Also according to the present invention there is provided a machine provided with means for preventing destruction of machine elements supported by bearing means and rotatable by a motor, comprising means defining a bore, the bearing means being disposed within the bore, deformable means loadable by the elements and disposed between the bearing means and the wall of the bore, and detector means extending within the deformable means, the motor being actuable by a signal generated in response to the detector sensing the occurrence of a predetermined extent of deformation to stop the machine.

The elements may comprise elements of a printing press shaft.

The elements may comprise elements of a rotary folding machine.

The deformable means may comprise at least one resilient spacer member engaging a rigid ring bearing which supports therein a shaft of the machine.

The machine may comprise three spacer members, equally spaced around the ring bearing.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings in which: Fig. 1 shows a partial longitudinal section through a processing group of a rotary folder, Fig. 2 shows a plan on a bearing provided with an embodiment of the present invention, and Fig. 3 shows a longitudinal section corresponding to Fig. 2.

Referring to the accompanying drawings, between machine walis 1 :1' of a rotary folding machine, two folding cylinders, for instance a folding blade cylinder 2 and a folding knife cylinder 3 together with associated gear wheels etc., are disposed. Shafts 4 of these cylinders are seated in bearing bores 5 in the machine walls 1:1' by means of shaft bearings 6. The shaft bearings 6 may for example be plain bearings, ball bearings or loose bearings. In the bearing in which the bearing deformation is to be measured, a sufficient gap remains between a bearing bush 7 and the wall of the bearing bore 5 to mount therein spacer members 8, distributed around the circumference of the bush 7. A relatively firm but just elastic plastics material may be used for the spacer members 8.An unforeseeable accumulation of the products to be processed can occur in certain circumstances, for example during faults. In this case, a deformation would occur in the spacer member 8' disposed in the direction of principal loading, and this deformation is measured. For this purpose an auxiliary bore 9 is provided adjacent to the bearing bore 5, which extends approximately in the main anticipated direction of loading. A plunger 10 penetrates through the web of material remaining between the two bores 5 and 9 and through a bore in the spacer member 8' so that it bears against the bearing bush 7. By means of the plunger 10, the position of a cranked lever 11 journalled at its apex point can be influenced, which lever has a contact 1 2 at the end of its long arm.Opposite to this contact is a contact adjustment screw 1 3. The end of the short arm of the cranked lever 11 is inserted into a transverse groove of the plunger 10, so that the movements of the plunger 10 are transmitted in a sensitive manner to the cranked lever 11.The plunger 10, cranked lever 11, contact 1 2 and the contact adjustment screw 1 3 are preferably parts of a conventional measurement pick-up 14, such as are used, for instance, in electronic fine indicators in length measuring techniques, and operating in the thousandth of a millimetre range. The measurement pick-up 14 is fixed by means of a threaded bore into the web of material remaining between the bores 5 and 9.

The low voltage u1, which is transformed into a control voltage u2, is applied to a transformer 1 5.

A relay 1 6 is disposed between the transformer 1 5 and the measurement pick-up 14, by which a switch 1 7 of an electrical circuit parallel to the low voltage u can be influenced. In this electrical circuit, a contactor 1 8 is disposed, which cooperates with a motor switch 1 9 of a main drive moto,r 20.

As soon as, for instance, in a rotary folder, accumulations of paper occur due to crumpled sheets, jams or the like, which in high-speed rotating printing presses can occur in fractions of a second, the commencing overloading of the machine parts manifests itself as an elastic deformation of these loaded elements. As soon as a deformation which approaches the permissible maximum value occurs, the machine signal "stop machine" must be triggered. When overload occurs, the plunger 10 as a consequence of the commencing bearing deformation is pressed, and via the cranked lever 11 and its contact 12 a contact is made with the contact adjustment screw 13, so that the control current circuit is closed.The relay 1 6 therefore responds, closes the switch 1 7 so that intervention takes place via the contactor 1 8 into the main current circuit of the machine at operating voltage u3 and the main motor 20 is switched off for example via the motor switch 1 9. By adjustment of the contact adjustment screw 13, the fine adjustment of the reference value can be carried out in such a way that even the commencement of overload of the bearing can result in triggering of the switching off signal. Instead of the arrangement of an intermediate current circuit, because the control current circuit does not provide sufficient power for actuating the contactor 18, a normal amplifier can be introduced.

An advantage of the above described embodiment is that the destruction of machine elements during faults or accidents is avoided, so preventing machine shutdown periods, repairs etc.

and the machine elements are protected by prompt disengagement of the machine even when irregularities occur.

Further, even a just commencing overload of machine elements can lead to shutdown of the machine, without the need for the products being processes to be observed either optically or in some other way.

Also the acceptable loading tolerance at a bearing can be finely adjusted in accordance with previous experience at the relevant bearing point and according to the thicknessses of material to be processed.

Embodiments of the present invention may be used in rotary printing presses and rotary folders, in which sheets or portions of sheets of materials are processed between cylindersjournalled at both ends. It may be possible that embodiments could be used at other positions in a machine at which unplanned accumulations of material between mutually co-operating machine elements under accident conditions etc. could in the last resort result in breakages.

Claims

1. A method of preventing destruction of machine elements supported by bearing means, comprising the steps of detecting deformation of deformable means disposed at the region of the bearing means and, on the deformation exceeding a predetermined extent, generating a signal to actuate means to stop the machine.

2. A method as claimed in claim 1, wherein the step of detecting deformation of the deformable means comprises use of a fine tolerance indicator, the indication of which is compared with a reference value to form a difference which when exceeding a predetermined amount corresponding to said predetermined extent causes amplified signals to be generated to actuate the means to stop the machine.

3. A method of preventing destruction of machine elements as claimed in claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.

4. A machine provided with means for preventing destruction of machine elements supported by bearing means and rotatable by a motor, comprising means defining a bore, and bearing means being disposed within the bore, deformable means loadable by the elements and disposed between the bearing means and the wail of the bore, and detector means extending within the deformable means, the motor being actuable by a signal generated in response to the detector sensing the occurrence of a predetermined extent of deformation to stop the machine.

5. A machine as claimed in claim 4, wherein the elements comprise elements of a printing press shaft.

6. A machine as claimed in claim 4, wherein the elements comprise elements of a rotary folding machine.

7. A machine as claimed in any one of claims 4 to 6, the deformable means comprising at least one resiiient spacer member engaging a rigid ring bearing which supports therein a shaft of the machine.

8. A machine as claimed in claim 7, comprising three spacer members equally spaced around the ring bearing.

9. A machine substantially as hereinbefore described with reference to the accompanying drawings.