GB2094767A

GB2094767A - Apparatus for feeding sheets to sheet-processing machines

Info

Publication number: GB2094767A
Application number: GB8206160A
Authority: GB
Original assignee: DOERRIES GmbH
Current assignee: DOERRIES GmbH
Priority date: 1981-03-17
Filing date: 1982-03-03
Publication date: 1982-09-22
Also published as: IT1155639B; JPS57160842A; GB2094767B; DE3110184A1; FR2502129A1; FR2502129B1; IT8267334A0; SE455496B; DE3110184C2; SE8200963L

Abstract

Sheets are supplied to a processing machine such as a gluing machine from a conveyor belt (5) carrying a sheet stream in overlapping formation. A first sheet (4'') comes to rest lined up against the front stop (9) and after the latter has been folded down the sheet (4'') is accelerated from a standstill to the machine speed by means of an accelerating roller (10) and is transferred to the sheet transporting roller (14) with its co-operating pressure rollers (15). The start impulse for accelerating the sheet and simultaneously folding down the front stop (9) is generated by a rotation initiator which is actuated by a single-revolution shaft; the timing rollers (11) are lowered onto the accelerating roller whilst the latter is still stationary. The motor drive for the accelerating roller is separate from the drive of the transporting roller, and the feeding can be adjusted for sheets of different lengths. <IMAGE>

Description

SPECIFICATION Apparatus for feeding sheets to sheet-processing machines such as gluing machines The invention relates to apparatus for feeding sheets to sheet-processing machines such as gluing machines, for example, of the type having a sheet transporting roller for revolving at the speed of the machine, a pressure roller, a device for accelerating from a standstill to the machine speed the sheet which is resting against a front stop and which is to be fed to the transporting roller after the front stop has been folded down, and a single-revolution shaft for controlling the accelerating device.

Such apparatus is used, for example, for feeding cover sheets which are to be glued onto a supporting web. The stacked sheets are supplied in ragged formation to the apparatus where they are first lined up against the so-called front stop and then, after this has been folded down, they are fed one at a time to the transporting roller which feeds the sheets to the actual processing machine at a constant machine speed. The cover sheets must be fed precisely at constant intervals corresponding to the length of the sheets involved. Furthermore, it must be possible to adjust the feed apparatus for sheets of different lengths.

In a known apparatus of this type the sheets are fed by means of gripper devices which move to and fro over cams, these cams being connected to the transporting rollers via a coupling which is engaged and disengaged by the single-revolution shaft in time with the succession of sheets (see German Patent Spec. DE-AS 24 34 625). The individual components are under very great stress, especially with the desired high throughput of sheets and the high machine speeds connected with this. Severe wear occurs in particular in the coupling mechanism, and this very considerably reduces the economic viability of such apparatus.

An object of this invention is to provide apparatus of the type described in the introduction which, despite a high sheet throughput, is not subject to a high degree of wear and provides precise feeding at a synchronous speed which can be adjusted to the machine speed for sheets of different lengths.

According to the invention such apparatus is characterised in that the accelerating device has an accelerating roller driven by a rotary speed controlled drive motor which is separate from the drive of the transporting roller, the sheet which is to be accelerated being pressed against this accelerating roller by means of a timing roller.

Apparatus according to the invention has no parts which are susceptible to wear such as a coupling or the like.

It can be driven at extremely high speeds.

When the trailing edge of a sheet gripped by the transporting roller has passed the accelerating roller the timing rollers drop down on the still stationary accelerating roller. The new sheet resting against the front stop is clamped between the accelerating roller and the timing roller. A rotation initiator gives the start impulse for the accelerating roller which accelerates this sheet from a standsill to the machine speed.

In a preferred embodiment of the invention the maximum rotary speed of the drive motor for the accelerating roller is controlled by the transporting roller. This speed can be adjusted electronically. Advantageously, the distance between the gaps formed by the sheet transporting roller and the accelerating roller with their respective co-acting rollers corresponds at most to the smallest sheet length to be conveyed and at least to double the distance for acceleration to the machine speed.

In a further advantageous development of the invention the distance between the front stops and the gap between the sheet transporting roller and the pressure rollers corresponds to at least the distance necessary for acceleration to machine speed. This distance amounts to at least half the extent which is covered during the acceleration by the preceding sheet at the machine speed.

In order that the invention will be readily understood, one embodiment example will be explained in more detail with reference to the accompanying drawings, in which: Figure 1 shows schematically a side view of a gluing machine with feed apparatus according to the invention.

Figure 2 shows schematically a plan view onto the plant shown in Fig. 1.

Figure 3 is a schematic side view of the feed apparatus on its own, on a larger scale.

The sheets 4 are supplied from the sheet feeder 3 via a conveyor belt 5 to the feed apparatus which is designated 6 as a whole, from whence they are supplied to the actual gluing machine 7 in which they are glued onto a supporting web 8. The sheets 4 are delivered in ragged formation by the sheet feeder 3. The foremost sheet 4" comes to rest lined up against the front stop 9. After the trailing edge of the outgoing sheet 4' (Fig. 3) has passed the accelerating roller 10, the timing rollers 11 are lowered onto the stationary accelerating roller 10, thereby clamping the sheet 4" in between them. Driven by the single-revolution shaft 1 2 of the sheet feeder 3, a rotation initiator 1 3 (Fig. 2) gives the start impulse for the acceleration of the sheet 4" resting against the front stop 9. The front stop 9 is simultaneously folded down.The acceleration and the simultaneous folding down of the front stop 9 are therefore initiated at an exactly fixed number of degrees round the single-revolution shaft 1 2. During the acceleration of the sheet 4", the sheet 4' which was previously gripped by the sheet transporting roller 14 with the pressure rollers 1 5 covers the distance s at a constant machine speed. Meanwhile, the sheet 4" is accelerated from nil to the full machine speed and is conveyed thereby over the distance s/2 so that at the instant when it reaches the machine speed it comes to rest exactly with its leading edge against the trailing edge of the preceding sheet 4'.The control of the acceleration of the drive motor 1 6 for the accelerating roller 10 is effected electronically in a known way, via the rotation initiator 17, depending on the sheet transporting roller 1 4 driven at the machine speed via the transmission drive 1 8 of the gluing machine 7 via the control device 20, and a rotation initiator 1 9 also feeds the machine speed of the sheet transporting roller 14 into the control device 20. The single-revolution shaft 1 2 is also driven by the transmission drive 1 8 via regulating gearing 21 by means of which the rotary speed of the single-revolution shaft is adjusted according to the sheet length involved.

After the machine speed has been attained, the accelerating roller continues to rotate at a constant speed until the sheet is gripped by the sheet transporting roller 14.

With a constant distance sthe acceleration is therefore varied only dependent on the machine speed. The format length has no direct influence on the acceleration.

Claims

1. Apparatus for feeding sheets to sheetprocessing machines such as gluing machines, for example, of the type having a sheet transporting roller for rotating at the speed of the machine with a pressure roller, a device for accelerating from a standstill to the machine speed the sheet which is resting against a front stop and which is to be fed to the transporting roller after the front stop has been folded down, and a single-revolution shaft for controlling the accelerating device, characterised in that the accelerating device has an accelerating roller arranged to be driven by a rotary speed controlled drive motor which is separate from the drive of the transporting roller, the arrangement being such that the sheet which is to be accelerated is pressed against the accelerating roller by a timing roller.

2. Apparatus according to Claim 1, characterised in that the maximum rotary speed of the drive motor for the accelerating roller is controlled by the transporting roller.

3. Apparatus according to Claim 1 or 2, characterised in that the distance between the gaps formed by the sheet transporting roller and the accelerating roller with their respective co-acting rollers corresponds at most to the smallest sheet length which is to be conveyed and at least to double the distance (s) for acceleration to the machine speed.

4. Apparatus according to one of Claims 1 to 3, characterised in that the distance from the front stop to the gap between the sheet transporting roller and the pressure roller corresponds at least to the distance (s/2) required for acceleration to machine speed.

5. Sheet-feeding apparatus, constructed, arranged and adapted for use substantially as herein before described with reference to, and as shown in, the accompanying drawings.