Sheet-feeder for a machine manufacturing those sheets.

The invention relates to a feeder for sheets in a sheet processing machine, in particular a sheet-fed rotary printing machine, having the generic features according to the preamble of claim 1.

Such investors is known from DE-OS 36 09 550th Nozzles for Vorlockerung are juxtaposed in this arrangement in a row adjustable and addressed at the level of the upper arch in the sheet stack on the sheet trailing edge and constantly acted upon by blown air from a central blown-air. The feed to the other, against the former differently shaped nozzles is in the working cycle of the investor regulated to form a sort of bubble of air-inflated for the top, lifted by suction separator sheet. The adaptation to different sheet material, in particular to different paper grades is done by adjusting the height and the direction of action of the nozzles of the air stream and by appropriate selection of the nozzle shapes. Despite such measures, it is primarily used for increasing machine speeds before, that the bow in the sheet pile located at the trailing edge and / or at the front edge not disengage and sheets are not detected properly by the conveying means, which transport it to the investor, or multiple sheets reach the investors and trigger a machine stop. In particular, heavy papers, such as cardboard, tend to wave formations, of which the tight contact of the sheet be lifted suffers the suction separator, but even with thin, tight paper the reliability of the investor function is limited. The uppermost, raised at its rear edge sheet is not sufficiently below blown with air-inflated so that its transportation is not assured.

For the purpose of achieving a better support of the sheet after taking off from the sheet pile and an improved function of the investor, it is known from DE-PS 1,699,507, to increase the number of suction separator and also an increased number of pull suckers in several over the arranging sheet width extending rows in the conveying direction of the sheet in succession, which, however, a considerable amount of additional work and the air demand, thus the energy demand, rising accordingly.

Object of the invention is to achieve an increase in the operational reliability of the investor regardless of the quality of the processed sheet material and an increase in printing speed with economical means and a lower energy consumption. The invention solves this problem by forming characteristics according to the characterizing portion of claim 1.

This design features separate blast air is blown with a relation to the central air increased pressure from a body independent of the general blast air of the investor blowing air in the working cycle of the investor to separate the trailing edge of the uppermost sheet from the sheet stack by loosening blowers advantageous jerky in the stack, this sheet in to manner known per se is raised by a suitable separating device at the trailing edge. Among these n raised arch supporting air is blown with increased pressure from the separate blowing air in the working cycle of the machine so that the separation of this sheet from the underlying sheet through to the sheet leading edge with a substantially improved operational reliability than previously done. The air cushion have built up can be defined individually to the requirements as a function of the sheet material and the engine speed, and therefore more optimal than before. For investors who have a suction head with a on the rear edge of the top sheet can be placed in the sheet pile pressure foot, through the normally carrying air is blown under the top sheet, the discharge of supporting air from the separate blowing air is advantageously on the nozzle in this sensor foot and more , arranged alongside the supporting air nozzles, which can be directed from the arc center angle to the side in a conventional manner, or possibly even more than one of these nozzles.

The supply of support air nozzle (the pressure foot and in supporting air blowers) and loosening blowers with separate blast air is advantageously effected by a relatively small compressor via a control valve, which is formed as a rotary valve and the drive of the suction head, it is particularly driving members of the governor foot coupled. This feature is a particular advantage because it is facilitated a synchronous operation of the rotary valve with the drive members of the suction head, in particular the governor foot and can be the blow times for separate blast air determines exact and possibly dimensioned extremely short. AuÆerdem can be individually controlled by the separate supply of nozzles for carrier air and for separating air, as they blow air is independent of the conditions of the general blast air. In particular, these separate blowing air supply for the separation and the lower blowing the lifted sheet allows higher pressures, optionally at reduced blowing times. The general Blaslufterzeugung must not generate the higher pressure, but may function with a reduced pressure, in which an economic advantage.

In one advantageous embodiment of the inventive concept, some of the measures provided at the trailing edge in the upper sheet of the sheet stack trailing edge blowers can also be connected to the separate blast air, whereby the flexibility to adapt to special operating conditions by the available higher pressure is increased.

By supplying the carrier air at the top, lifted sheet blowing in nozzles with separate blowing air not only the reliability is increased, but at the same time reduces the amount of air required because shorter blowing times are possible or the general blast air can operate at lower pressure, so that a lesser energy consumption occurs, thereby reducing pollution.

In the drawing the invention is shown in one embodiment.

Show it:<dl id="dl0001"><dt>Fig. 1</dt><dd>a schematic plan view of a feeder with a circuit diagram for the air supply,</dd><dt>FIG. 2</dt><dd>a representation corresponding to Figure 1 with a modified circuit diagram for the air supply,</dd><dt>Fig. 3</dt><dd>a rear view of acting on the sheet trailing edge nozzles in relation to FIG 1 and 2 on an enlarged scale,</dd><dt>Fig. 4</dt><dd>a section along the line IV - IV of Figure 3 and</dd><dt>Fig. 5</dt><dd>a section along the line V - V of FIG. 3</dd></dl>

Figures 1 and 2 show a plan view of the top sheet 1 in the sheet stack and the reproduced as a block scheme suction head 2. At the bottom of the suction head 2 is the driven in the working cycle of the investor pressure foot 3. z for example from one or more separating suckers existing separation device for lifting the uppermost sheet from the sheet pile is not shown in the drawing for reasons of clarity. The design of this separating device can be effected in conventional manner.

In the area of ​​the rear edge of the top sheet 1 in the sheet stacks in a row next to each other vertically and laterally adjustable on the sheet trailing edge directed loosening blowers 4 (Fig. 3 and 5) on a transverse tube 5 arranged. On the tube 5 are arranged from the center outwards adjustable offset trailing edge blowers 10 as loosening blowers for separating the uppermost sheet. To the side of the sheet stack further Diagonal blowers 6 are provided in the upper arch. The trailing edge blowers 10 and the diagonal wind 6 to be supplied in the circuit diagram of FIG. 1 via lines 7 of a central air supply 8 from or another blowing air continuously blown air. For the nozzles 9 in the pressure foot 3 (Fig. 3 and 4) as well as looking for two or more laterally arranged alongside and diagonally in Example outwardly supporting air blower 11 and loosening blowers 4 is a separate blast air by means of an in performance compared to the central unit considerably reduced compressor 12 provided that is effective and adjustable independently with an increased pressure relative to the central air supply eighth If necessary, but also the trailing edge blowers 10 can be acted upon by a separate blast air. The blowing air from the dedicated compressor 12 is supplied and controlled by the line 13 via a rotary valve 14, the rotary valve 14 is provided with drive members of the suction head, preferably with drive members of the governor foot 3 coupled, so that the rotary valve 14 runs synchronously with the Tastfußbewegung to and enables precise control of the separate blowing air into the nozzle 9 and winds eleventh

If necessary, can according to the circuit diagram in Fig. 2 and nozzles into the trailing edge blowers 10 with the separate blast air from the compressor 12 or another source separate blast air are supplied, if thereby increasing the operational reliability during separation and especially when you lift the topmost sheet from the sheet pile is achieved.

LIST OF REFERENCE NUMBERS

<dl id="dl0002"><dt>1</dt><dd>arc</dd><dt>2</dt><dd>suction head</dd><dt>3</dt><dd>pressure foot</dd><dt>4</dt><dd>loosening blowers</dd><dt>5</dt><dd>supporting tube</dd><dt>6</dt><dd>Diagonal Winds</dd><dt>7</dt><dd>lead</dd><dt>8th</dt><dd>Central air supply</dd><dt>9</dt><dd>blow nozzle</dd><dt>10</dt><dd>Trailing edge blowers</dd><dt>11</dt><dd>Supporting air blower</dd><dt>12</dt><dd>compressor</dd><dt>13</dt><dd>lead</dd><dt>14</dt><dd>rotary valve</dd></dl>