FR2670066A1 - Shaft for the mechanism of office-type equipment - Google Patents

Abstract

Lightweight shaft, resistant to bending and of low cost. It consists of a rigid metal body (1') on which shaft-bearing elements (5, 6, 7, 10) and/or drive elements are locally overmoulded. The application of this type of shaft is especially that of fixing a strip, for example a sheet, moving against a region of a read or write device and/or driving of this strip in office-type equipment, and especially widely marketed fax machines.

Description

Shaft for office equipment type mechanism.

The invention relates to a shaft for a mechanism of material of the office automation type with wide distribution and in particular for a facsimile mechanism comprising a drive roller and / or paper plating.

Many office automation devices include mechanisms with rollers for driving a strip and / or pressing it against a device, for example a thermal print head or an optical reader, in the case of a paper strip. .

These rollers are carried by shafts which are generally relatively long for reasons related to the usual formats of printed sheets.

Other trees with corresponding lengths are sometimes arranged for other purposes in the mechanisms of these materials, the dimensions of which are at least partly a function of the formats mentioned above.

All these shafts are conventionally made of stainless steels which make it possible to obtain the desired mechanical characteristics but which are considered to be very expensive for mass market materials.

In addition, it is conventional to have to machine these shafts with tight tolerances at the bearing surfaces where they come to rest and possibly at the level of the bodies responsible for moving them, or the machining of such steels is relatively difficult and therefore more expensive than 'it is not desired.

The invention therefore provides a shaft for a drive roller and / or tape plating, intended for a hardware mechanism of the office type, in particular for a fax machine.

According to a characteristic of the invention, the shaft consists of a rigid metal body on which bearing elements for the shaft and / or drive are overmolded.

The invention, its characteristics and its advantages are explained in the following description, in conjunction with the figures listed below.

Figure 1 shows a first example of a tree according to the invention.

Figure 2 shows a second example of a tree according to the invention.

The tree for office-type equipment presented in FIG. 1 is for example intended to constitute a drive roller and / or plating paper for a fax machine.

This type of roller is generally only subjected to low torques, on the other hand it must have good resistance to bending, in particular when, relatively long, it must press as uniformly as possible a sheet of paper in movement against area of a reading or writing device, as mentioned above.

The shaft according to the invention preferably comprises a rigid metallic body 1, made of a material having good resistance to bending, for example common steel, optionally an aluminum alloy, of low cost, the latter making it possible to more to obtain an advantageous low inertia when the roller must allow rapid accelerations or decelerations.

This metal body may possibly be bare over most of its length, in the embodiment envisaged here it carries a drive roller whose at least the periphery is made of an elastomeric material O.

Protection of the body 1 against corrosion, in the case of a shaft with a body made of steel, is for example produced by coating, in particular by zinc plating, after or often before machining.

A light machining by removing material or by deformation, for example by turning, knurling or crushing, is carried out on the body 1, so as to create immobilization means at locations where it is planned to overmold complementary elements in usual molding material, for example an acetal resin
These complementary elements are in particular bearing surfaces 2 and 3 by which the shaft rests in fixed bearings 9, for example located at its ends.

Such bearings 9 are for example of the smooth type and allow the rotation of the shaft along its axis, in the mechanism with which it cooperates, these bearings and this mechanism not being developed here insofar as they have only 'an indirect relationship with the invention.

In an exemplary embodiment, hollows are produced
in particular at the thinned or unthinned ends of the metal body, before overmolding, so that the material injected in the pasty state, during overmolding, comes into the hollows produced on the body 1 and ensures immobilization, on the body 1, elements molded by its hardening.

Of course equivalent or similar, but possibly more efficient, arrangements can also be implemented, a longitudinal plate of limited length that can, for example, be formed before overmolding at at least one of the ends, if the corresponding overmolded element must transmit a torque greater than that which is likely to support the arrangement mentioned above.

At least one of the overmolded elements can also incorporate a drive element of the shaft or of another movable part of a mechanism by this shaft, this overmolded drive element comprising for example a drive cavity 4 , for example with a prismatic appearance produced at the end of the shaft or even longitudinal longitudinal grooves at the end of the shaft, opening out and regularly spaced, for example in a cruciform arrangement.

This drive element can also take the form of a pinion, a pulley or a wheel, such as the toothed wheel 5 supposed to be molded in a single piece with one of the two bearing surfaces 6, 10 in the variant. 1 'shown in Figure 2.

 One of the elements overmolded on the metal body 1 of a shaft is possibly a carrying mandrel 7, overmolded, at the same time as the bearing surfaces 6, 10, over a length which corresponds for example to the width of a sheet of paper. with which the tree will be brought to cooperate.

This mandrel 7 is covered by a cylinder 8, preferably of small thickness, in a material chosen for its good adhesion, for example an elastomer, this external cylinder being intended to serve as a contact element and / or as a sheet drive or tape, in the application example envisaged here.

The mandrel 7 is then fixed on the metal body 1 'of the shaft as are the bearings 6, 10 due to the penetration of the molding material which composes them in recesses 11 formed for this purpose on this metal body 1' , as indicated above.

Claims (5)

1 / Shaft for drive roller and / or tape plating, intended for an office-type hardware mechanism, in particular for a fax machine, characterized in that it consists of a rigid metallic body (1 or 1 ' ) on which elements (2, 3, 5, 6, 7, 10) of shaft support and / or drive are overmolded. 2 / shaft according to claim 1, characterized in that the bearing and / or drive elements are overmolded at the ends of the metal body which are roughly machined to allow each immobilization relative to this body of the element which is there molded.  3 / Shaft according to at least one of claims 1, 2 characterized in that the rigid metallic body is constituted by a steel rod protected against corrosion by coating. 4 / Shaft according to at least one of claims 1, 2 characterized in that the rigid metallic body consists of an aluminum alloy rod. 5 / shaft according to at least one of claims 1 to 4, characterized in that it comprises a mandrel (7) overmolded with the support and / or drive elements (5, 6, 10) to which is subject a thin elastomer cylinder (8), the assembly forming a drive roller for a sheet or strip movement mechanism.