MACHINE FOR AUTOMATICALLY COVERING ROLLERS WITH TUBULAR SHEATHS OF HIGH ADHERENCE MATERIAL

Abstract: The machine (1) comprises: support means (5) for supporting one roller at a time; guide means (14, 15) defining a guide channel in which a sheath portion (3) is contained substantially as an exact fit about its cross-section; gripping means (18) positioned at the front end of the guide channel to securely grip the sheath (3); and means for feeding compressed air into the sheath portion. Said support means (5) are axially movable relative to the guide means (14, 15) and to the gripping means (18).

Description: Description Machine for Automatically Covering Rollers with Tubular Sheaths of High Adherence Material Technical field This invention relates to a machine for automatically covering rollers with sheaths of high adherence material. Background art Conveying surfaces for goods of various kinds have for some time been formed from rollers having their outer surface covered with sheaths of mainly elastomeric materials, both to prevent the goods slipping during conveying and to reduce the effect of jolting on the conveyed products along the conveying path. Such rollers are still produced mainly manually or semi- automati call y. In practice, in the manual method one or more operators draw the tubular sheath produced in rolls onto tubes of various lengths, facilitated by using substances which aid slippage between the contacting surfaces. The semi-automatic method uses a machine having a base provided with a support on which a tube piece of predefined length is positioned and over which, using a gripper mounted on a carriage movable parallel to the tube, the sheath is progressively pulled, again using substances facilitating slippage between the tube outer surface and the sheath inner surface. Both the aforedescribed methods of operation have drawbacks. In the case of the manual procedure, the time required to implement the complete operating cycle is very lengthy, the operation being very fatiguing and costly, requiring the assistance of one or more operators. In the case of the semi-automatic procedure, the gripper covers the tubes by traction, resulting in contraction of the useful sheath cross-section, with consequent increase in the resistance to its drawing over the tubes, which has therefore to be aided by previously spreading interposed substances facilitating slippage between the contacting surfaces. However, as these substances cannot be completely eliminated they remain in situ so tending, when the rollers are used under load, to induce torsional slippage of the sheaths on the tubes, this slippage causing the products to rotate on the conveying surfaces because of speed differences between the roller outer surfaces, together with damage to the sheaths which, once rotated about their longitudinal axis, are subjected locally to abnormal stress conditions. An object of this invention is to solve the aforesaid problems of the known art by providing a machine for automatically covering rollers with tubular sheaths of high-adherence elastic material which enables this operation to be performed substantially automatically, with the minimum possible force and without the use of substances for facilitating slippage of surfaces which then retain residues when covering has been completed. Disclosure of the invention This and further objects are attained by a machine for automatically covering rollers with tubular sheaths of adherent elastic material as characterised in the claims. Further characteristics and advantages will be more apparent from the ensuing description of a preferred embodiment of a machine for automatically covering rollers with tubular sheaths of high- adherence elastic material illustrated by way of non-limiting example on the accompanying drawings, on which: Figure 1 is a schematic side view of the automatic roller covering machine of the invention in its maximum elongation configuration for covering rollers of large length; Figure 2 shows the same machine of the invention in its medium elongation configuration for covering rollers of small length; Figure 3 is a schematic cross-section through the machine of the invention on the plane III-III of Figure 1; Figure 4 is a schematic cross-section through the machine of the invention, as in Figure 3, taken on the plane IV-IV of Figure 1; Figure 5 is a detailed view of one embodiment of the horizontal support means for the rollers to be covered. With particular reference to the aforesaid figures, the reference numeral 1 indicates overall a machine for automatically covering rollers 2 with tubular sheaths 3 of high-adherence elastic material, The machine 1 consists essentially of an extendable bed composed of at least two half-beds 4a and 4b connected together telescopically. Of these, a first half-bed 4a is provided with means 5 for horizontally supporting the rollers 2 to be covered, and movable with outward and return travel between two end positions deter inable by relative means 6 on the basis of the length of the rollers 2, they being provided between the rollers 2 and the tubular sheaths 3 with compressed air feed means, not shown in detail for simplicity but described hereinafter. A second half-bed 4b is provided with means 7 for gripping the various portions of tubular sheaths used and maintaining them guided. The means 5 for supporting the rollers 2 consist of a cylindrical headpiece 8 into which one end of each roller 2 can sealedly fit, and which is provided with members 9 for gripping said ends. The headpiece 8 is mounted on a relative carriage 10 movable forwards and rearwards on suitable horizontal guides 11 rigid with said first half-bed 4a. The gripping members 9 consist of at least one pincer with horizontal jaws 12 pivoted bilaterally to the cylindrical headpiece 8 and able to penetrate into it to grip the front end of each roller 2 via corresponding longitudinal slots 8a provided in the headpiece 8 in diametrically opposite positions. The means 6 for determining the travel of said means 5 for supporting the rollers 2, as stated consisting of the carriage 10 and the relative cylindrical headpiece 8, consist of corresponding end-of-travel sensors 13 positioned in facing combination on said carriage 10 and on the front end of the second half-bed 4b. The means 7 for maintaining the tubular sheath portions 3 guided consist of a cradle-shaped guide 14 provided with comb-like walls having upwardly pointing teeth 14a, the guide 14 being rigidly fixed to the upper face of the second half-bed 4b and cooperating with an upper counter-guide 15 supported on a longitudinal support member 16 driven with vertical reciprocating movement by relative actuator means 17 interposed between it and said second half-bed 4b. The counter-guide 15 is also cradle-shaped with comb-like walls having lowerly pointing teeth 15a vertically aligned with the interspaces between the teeth 14a of the guide 14 in order to copenetrate with them when closed. Said means 14, 15 define for a sheath portion a guide channel of length substantially equal to the length of the roller 2 (and hence of the sheath portion) and of cross-section substantially equal to the cross-section of the sheath. Both at the front and rear end of said guide 14 and counter-guide 15 there are provided gripping means 18 and means 19 for guiding the ends of the tubular sheath portions. The gripping means 18 provided at the front end consist of a segment 15b of the actual upper counter-guide 15 positionable rigidly, in this case by means of a vertical rib segment 20, below said longitudinal member 16 at a fixed level lower than the comblike walls of said counter-guide 15 and horizontally offset from it. The guide means (and in part gripping means) 19 provided at the rear end consist of a gripper with its jaws 21 movable in a vertical plane coinciding with the longitudinal axis of the rollers 2 and arranged to retain the projecting end of these. Advantageously, the jaws 21 are provided at their far ends with corresponding appendices 21a ensuring centered gripping and for this purpose forming, when in their closed configuration, the opposing facing cavities of a hollow seat representing the ideal prolongation of said guide 14 and said counter-guide 15. In the preferred version of the machine 1 both the guide 14 and the counter-guide 15 are divided into usable submultiple adjacent sections supported by said longitudinal member 16 in a number dependent on the length of the rollers 2 to be covered. The compressed air feed means consist of a conventional compressed air production apparatus which is connected via a suitable connector to that end of the sheath 3 distant from that into which the roller 2 is inserted, and is arranged to expand the covering sheath portions by air injection while they are being drawn onto the rollers 2. The machine of the invention operates in the following manner: the half-beds 4a and 4b are positioned in accordance with the length of a batch of rollers 2 to be covered, by sliding the half-bed 4b on the half-bed 4a then locking the former to the latter by known means. An operator then arranges a roller 2 to be covered by inserting one of its ends into the headpiece 8, in which it is retained airtight, then resting the opposite end on the appendix 21a of the suitably open lower jaw 21. The guide 14 and the counter-guide 15 are also positioned in the open state, the operator then gripping the end of a reel 22 of tubular sheath 3 and bringing it firstly into contact with the opposite end of the roller 2 to be covered, then forcing it slightly onto this end. The counter-guide 15 is closed onto the guide 14 by the actuators 17 to an extent such as to axial ly retain the sheath portion 3 of length equal to the length of the roller 2 for which it is intended. Simultaneously the lower segment 15b on the upper counter-guide 15 forcibly clamps the end section of said sheath portion 3 to maintain it at rest. The jaws 21a are also closed onto the roller 2 but without pressing against it, so as merely to maintain it axially guided. The compressed air production apparatus begins to feed air, which flows into the sheath 3 to which it is connected, causing it to expand radially by a few millimetres. Simultaneously the carriage 10 commences its forward travel towards the half-bed 4b, resulting in progressive insertion of the roller 2 into the sheath 3, facilitated by said expansion. Penetration of the roller 2 into the sheath 3 is made possible by the guiding action of the channel formed by the guide 14 and counter-guide 15 and the gripping action of the means 15b, which grip the sheath at the front end of the guide channel. The sheath portion 3 enclosed within the guide channel and subjected to the pressure of the air fed into the sheath 3 is maintained, by the pressure of the air fed into its interior, in its radially expanded rectilinear configuration against the means 14 and 15, in this configuration it being penetrated by the roller 2 as the axial penetration thrust is applied to the sheath 3 at a point upstream of the guide channel (ie at the gripping means 15b). As the gripping means operate at a point in which the sheath 3 has not yet been drawn onto the roller 2, the contraction in the sheath cross-section produced by these does not obstruct the penetration of the roller 2 into the sheath 3. When the carriage has reached its preset end-of-travel position, detected by the sensors 13, it stops moving because at this stage the roller has been completely covered by the relative sheath portion 3. Before the carriage 10 stops, the jaws 21a open, having now fulfilled their purpose. When stoppage has occurred, the guides 14 and 15 also open and that end of the roller 2 inside the headpiece 8 can be gripped by the jaws 12, which enter the headpiece 8 through the longitudinal slots 8a. The carriage 10 then undergoes its return travel dragging with it both the covered roller, and the sheath 3 through a portion of length equal to the length of the covered roller 2, this portion being automatically deposited in the guide 14. A conventional cutting member, indicated on the drawings by 23, then cuts through the sheath 3 at the end of the covered roller 2, and simultaneously arranges the front end of the sheath 3 for a new roller 2. Finally, the jaws 12 are opened and the covered roller 2 can be extracted from the machine 1. If a batch of short-length rollers is to be covered, after positioning the two half-beds 4a and 4b at the correct distance apart one or more sections of said guide 14 and counter-guide 15 can be removed from the longitudinal member 16 and the remainder be moved into abutting contact, and the segment 15b then be fixed to the longitudinal member 16. It has been found in practice that the described invention attains the stated objects. Numerous modifications and variants can be applied to the invention conceived in this manner, all falling within the scope of the inventive concept. Moreover all details can be replaced by others technically equivalent. In practice the materials used and the shapes and dimensions can be chosen according to requirements, but without leaving the scope of protection of the following claims.

Claims: Cl aims 1. A machine for automatically covering rollers with tubular sheaths of adherent elastic material starting from a roll of sheath of indeterminate length, characterised by comprising: support means for supporting one roller at a time, guide means defining a guide channel in which a sheath portion is contained substantially as an exact fit about its cross-section, gripping means positioned at the front end of the guide channel to securely grip the sheath, and means for feeding compressed air into the sheath portion, said support means being axially movable relative to the guide means and to the gripping means. 2. A machine as claimed in claim 1, characterised by comprising an extendable bed composed of at least two half-beds connected together telescopically, and of which a first half-bed carries, for the rollers to be covered, said horizontal support means movable with outward and return travel between two end positions determinable by relative means on the basis of the length of the rollers, the second half-bed carrying the gripping means and guide means for the tubular sheath portions. 3. A machine as claimed in claim 2, characterised in that said roller support means comprise a cylindrical headpiece into which one end of each roller can sealedly fit, and which is provided with members for gripping these ends, the headpiece being mounted on a relative carriage movable forwards and rearwards on suitable horizontal guides rigid with said first half-bed. 4. A machine as claimed in claim 3, characterised in that said gripping members consist of at least one pincer with horizontal jaws pivoted bilaterally to the cylindrical headpiece and able to penetrate into it to grip the front end of each roller via corresponding longitudinal slots provided in the headpiece in diametrically opposite positions. 5. A machine as claimed in claim 3, characterised in that said means for determining the travel of said roller support means consist of corresponding end-of-travel sensors positioned on said carriage and on the front end of said second half-bed. 6. A machine as claimed in claim 3, characterised in that said guide means for tubular sheath portions comprise a cradle-shaped guide provided with comb-like walls having upwardly pointing teeth, and cooperating with an upper counter-guide also cradle-shaped with comb-like walls having lowerly pointing teeth vertically aligned with the interspaces between the teeth of the first guide in order to copenetrate with them, means being provided to cause said guide and counter-guide to transversely approach and withdraw from each other. 7. A machine as claimed in claim 6, characterised in that on the front end of said guide and counter-guide there are provided means for gripping the tubular sheath, these comprising a segment of said upper counter-guide positionable rigidly below said longitudinal member at a fixed level lower than the comb-like walls of said counter-guide. 8. A machine as claimed in claim 6, characterised in that on the rear end of said guide and counter-guide there are provided guide means for the tubular sheath, these comprising a gripper with its jaws movable in a vertical plane coinciding with the longitudinal axis of the rollers and arranged to support the projecting end of these. 9. A machine as claimed in claim 8, characterised in that said jaws are provided at their far ends with corresponding centered gripping appendices forming, when in their closed configuration, the opposing facing cavities of a hollow seat representing the ideal prolongation of said guide and said counter-guide. 10. A machine as claimed in claim 6, characterised in that said guide and counter-guide are divided into usable submultiple adjacent sections supported by said longitudinal member in a number dependent on the length of the rollers to be covered. 11. A machine as claimed in claim 1, characterised in that said air feed means consist of at least one compressed air production apparatus which is connected via a relative airtight connector to that end of the sheath/sheath portions distant from the insertion end, and arranged to expand the covering sheath/sheath portions by air injection while they are being drawn onto the rollers. 12. A machine as claimed in claims 2 and 6, characterised in that said guide is rigidly fixed to the upper face of the second half-bed, said upper counter-guide being supported on a longitudinal support member driven with vertical reciprocating movement by relative actuator means interposed between it and said second half-bed.

Inventors: LUPPI ANDREA, LUPPI, ANDREA
Applicants: FINMART S R L, LUPPI ANDREA, FINMART S.R.L., LUPPI, ANDREA
Application year: 2000
Main classification: B29D31
IPC codes: B29C63