DE69504545T2 - Process and device for removing waste in a saw - Google Patents

Description

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to an apparatus and method for removing waste from a saw, and more particularly to such an apparatus; which cuts multi-ply material such as log rolls of toilet and kitchen tissue paper and stacks of folded facial and similar paper towels in the transverse direction.

Such a device is intended to transfer cut sawn material from a saw conveyor through the saw housing to a conveyor system, which then feeds a packaging system. The saw conveyor is the device that guides the sawn material through the cutting process. Typically, a log roll (rolled product) or stack (folded product) has an overhang (trimming) at the ends, which represents waste and must be disposed of or recycled.

In the manufacture of consumer goods such as toilet paper and kitchen towels, the jumbo or machine rolls are transferred from the paper machine to a conversion area where they are rewound. The machine rolls are unwound, the webs are perforated in the transverse direction and then wound into parent rolls with a diameter corresponding to the retail size. Typical rewinders are shown in Applicant's US patents Re 28 353 and 48 28 195, which deal with a center and a surface winder, respectively. These machines generally provide a parent roll with a width equal to the web unwound from the machine roll.

The main roll is then cut transversely with a saw, producing a large number of retail-sized rolls and two trim rings at the ends. A typical example of a main roll saw is the applicant's US patent Re 30 598. The trim rings at the ends of the main roll are necessary because the width of the web unwound from the machine roll cannot be an exact even multiple of the number of individual rolls to be produced from the main roll. A certain amount of overhang is provided to ensure that the rolls have clean, smooth faces at the ends of the main roll.

Accordingly, stacks - in contrast to master rolls - are made of a multi-layer web material. Exemplary folding machines are disclosed and described in the applicant's US patents 31 95 882 and 35 72 681.

In any case, the trimmings must be disposed of - usually by catching the roll or stack and letting the trimmings fall under their own weight. When entering the trimming area In a trim removal device, for example, the trim is not transferred to the downstream conveyor system, but is allowed to fall freely and is thus removed from the flow of sawn material. However, the trim must then be removed separately from the saw housing - for example with a conveyor belt or a suction system. Examples of trim removal devices currently in use are mechanical gripping fingers (above the product, as stated in Applicant's US Pat. No. 4,977,803), round belt conveyors (under the sawn material), single or double suction belts (above the sawn material), side pressure pads (on the chain conveyor) and slide bars (located to the side of the sawn material).

The invention provides a method and a device as defined in the appended independent claims. According to one embodiment of the invention, the removal steps are carried out by blowing the trimmings upwards into a discharge pipe from below with an upwardly directed blast of air. Alternatively or additionally, the discharge pipe can be provided with a suction device in order to support the upward movement of the trimmings.

In order to secure the product article adjacent to a trim piece against upward movement, a carriage is provided for each end of the elongated section, i.e. above the most upstream and the most downstream product article.

This carriage is arranged between the discharge pipe and the product object and runs with the latter to ensure that it is not carried away by the upward air flow. For example, a carriage is equipped with a gripping device and accelerates to the speed of the sawn material, takes hold of the last product item cut off and moves it away from the trailing trimming or product ram. As the carriage passes through, it allows the air flow to carry the trailing trimming out of the product area.

The carriages can be driven by a servo actuator (motor, pneumatic or hydraulic cylinder), a mechanical device (cam and lever), an air cylinder with proportional valve, a stepper motor, etc. The present invention is novel in that it combines the functions of the trim removal and trim discharge systems. It provides a means of removing and discharging the trim immediately after cutting, while the product is still on the saw conveyor, as compared to transferring the product to a trim removal device to remove the trim and then discharging the trim. The invention is simpler in that it does not handle each trimmed product item separately, but only the first and last of each log or stack. This means that there is less product marking and less maintenance. The invention provides a means for quickly changing the cutting length, the master roll diameter or stack height, the master roll or stack length and the trimming width.

Other objects and advantages of the invention will become apparent from the constructional details set forth in the following description.

SHORT DESCRIPTION OF THE DRAWING

The invention will now be described with reference to the accompanying drawings.

Fig. 1 is a substantially diagrammatic side elevation of a known roller saw;

Fig. 2 is a partial perspective of the known grippers;

Fig. 3 is a partial side elevational view, partly in perspective, of an arrangement according to the teachings of the present invention;

Fig. 4 shows a graph of speed as a function of time for the saw head, conveyor and gripper during the removal of the leading or trailing trim;

Fig. 5 shows, similar to Fig. 3, the beginning of a trimming removal cycle;

Fig. 6-17 show, analogous to Fig. 5, the arrangement of the elements and the product in successive stages of the cycle (view sequence);

Fig. 18 is a representation analogous to Fig. 3, but without diagrammatic parts;

Fig. 19 is a sectional view taken along line 19-19 of Fig. 18; and

Fig. 20 is a plan view of the device shown in Figs. 18 and 19.

DETAILED DESCRIPTION State of the art

In Fig. 1, reference numeral 30 generally designates the frame of the sawing device. Starting at the right or upstream end, reference numeral 31 generally designates the conveyor for the roll (or stack) to be sawn. On conveyor 31, conventional stationary lateral rails form trays for the product or workpiece. This sawn material is pushed forward by rams 32, 33 (see Fig. 2) on the horizontal path P (see right part of Fig. 1). This illustration comes from US-PS 4,977,803, where on the left the ram 32 was shown as the state of the art at the time and on the right the new ram 33 according to the teaching of this patent. The old rams 32 are used in the present invention.

Referring again to Fig. 1, reference numeral 34 designates a saw housing for a high-speed through-feed saw, generally designated 35, having circular saw blades 36. Such a saw is disclosed in the applicant's previously mentioned US patent Re 30,598. However, the present invention is not limited to a specific type of saw; it is only necessary to have trimmings on a longer roll (or stack). For example, the invention is applicable to intermittently operating saws, as shown and described in the applicant's US patent 3,213,731.

Fig. 1 shows grippers 37 downstream of the saw 35, which are also shown in Fig. 2. The grippers 37 are arranged in pairs for each tub (see e.g. 37a, 37b) and are suspended from crossbeams 38 which are supported by a conveyor with spaced chains, one of which is shown in Fig. 2 at 39.

Finally, in the prior art illustration in Fig. 1, the reference numeral 40 generally designates a suction chute for trim removal and the reference numeral 41 the downstream conveyor system.

In the prior art illustration in Fig. 2, the frame is shown in part as at 30 and the troughs at 42 and 43. Normally there are two troughs to keep the transverse cutting forces in balance. As noted, Fig. 2 also shows roll grippers or grippers as at 37. These pick up the roll after cutting and guide it horizontally to the discharge conveyor 41. These grippers operate at the point where the endless ram chain runs around the rear sprocket, which is hidden by the guard plate 44 in Fig. 2. The rear sprocket is shown diagrammatically in Fig. 1 at 45.

The invention

Instead of letting the trimmings fall below the track P, which requires a receiving opening, they are led upwards, so that an opening 46 (see Fig. 1 left) can be omitted. The trough-forming rails are continued, as shown in Fig. 3 at 147, and protrude beyond the discharge conveyor 41. Upstream of the rails 147 in Fig. 3, the device is generally the same as in Fig. 1. The saw is therefore generally designated 35, the circular saw blade 36. For easier understanding, the new elements according to the invention are designated with reference numerals from the 100 series - for example the grippers according to the invention (in the In contrast to the known grippers 37 of Fig. 2) with 137 (cf. Fig. 3, middle left).

Also different are the discharge pipe 148 carried by the frame 30 and the air blast nozzles 149 below the track P as well as a control 150 which determines the position of the carriages 151, 152, which can perform a blocking function with respect to the discharge pipe 148. Furthermore, the control regulates the air blast arrangement 149 and, if necessary, the negative pressure in the discharge pipe 148. Generally speaking, three operating modes are provided: only air blast operation, air blast operation plus negative pressure and only negative pressure.

If the vacuum can be controlled in a suitable manner, i.e. can be switched on and off at suitable times, the downstream carriage 151 is not required. The grippers 137 are, however, required to move the product adjacent to the trim away from the trim and the ram. If this does not happen, the product roll presses the trim onto the ram so that it cannot be sucked upwards.

When the vacuum is continuously applied, the front (trailing end) slide 151 is required to prevent the product roll from being lifted. The rear (leading end) slide 152 is also required when the vacuum is switched on to hold back the leading product roll, because the vacuum must be applied long enough to ensure that the trim has been removed from the sawing area. The additional time brings the leading product roll into the influence of the vacuum.

Sequence of steps for trimming removal

First, reference is made to the diagram in Fig. 4. The reference number 153 designates the speed profile of the saw head. Since two saw blades 36 are used, the profile is a "rectified" sine wave, but only the relatively flat crest characterizes the saw movement during the cut. The reference number 154 designates the start of the cut, the reference number 155 the end of the cut.

The reference numeral 156 indicates the speed profile of the conveyor, which is a straight line, i.e. the speed is constant. The other line 157 represents the speed profile of the grippers; this speed is higher than that of the saw head or that of the conveyor.

Reference is now made to Fig. 5, which shows the state of the machine parts and the product items at the beginning of a trim removal cycle. For this purpose, a cycle is defined as starting with the ring at the rear (trailing) end and ending with the leading (leading) ring of the next log roll or stack of multi-layer web sawn material.

Here, the front trimming carriage 151 begins to accelerate to the speed of the feed conveyor 31. The air jet nozzles 149 are switched off and the rear trimming carriage 152 is in the waiting state. Here, the product roll on the left side is still pushed forward by the ram 42, but runs slower than the discharge conveyor.

In Fig. 6, the front trimming carriage 151 has now reached the speed of the conveyor 31; the gripper mechanism 137 pivots into the gripping position in order to accelerate the product roll to the speed of the conveyor 41. In the embodiment shown, 50 ms elapse between the states of Fig. 5 and 6.

Reference should now be made to Fig. 7, which shows the state approximately 150 ms after that of Fig. 5, i.e. 150 ms after the start of the cycle. In Fig. 7, the front trimming carriage 151 now runs at the speed of the discharge conveyor 41 and begins to expose the opening of the discharge pipe 148, from which a certain suction may act on the product - in particular on the rear trimming ring TT, which the ram 42 pushes forward.

In Fig. 8, which shows the time approximately 350 ms after the start of the cycle, the condition corresponds to that of Fig. 7, except that the product roll and the trim ring have been advanced further and the air jet nozzles 149 have been switched on. The opening at the lower end of the discharge tube 148 is now essentially exposed. After 450 ms (Fig. 9), the rear trim ring TT is well inside the discharge tube 148. At the same time, the rear trim carriage 152 begins to accelerate to a speed slightly above that of the feed conveyor 31.

As shown in Fig. 10 (550 ms), the front trimming carriage 151 is in the front waiting position, in which it has come to a standstill, and wants to accelerate backwards in order to bring its upstream end to the front edge of the discharge pipe 148; this state is shown in Fig. 11 (650 ms; referred to as waiting position 2). The rear Trimming carriage 152 has meanwhile reached the maximum speed slightly above that of the feed conveyor 31. The air jet nozzles 149 are still switched on and the grippers 137' of the rear trimming carriage 152 have been pivoted into the gripping position; see Fig. 10.

In Fig. 12 (750 ms), the front trimming ring TL begins to enter the discharge tube 148; in Fig. 13 (850 ms), the front trimming carriage 151 begins to accelerate to return to its first waiting position.

In Fig. 14 (950 ms), the front trim carriage 151 is in the waiting position, the air blast nozzles 149 are on and the rear trim carriage 152 is running at its maximum speed (slightly faster than that of the infeed conveyor 31). In Fig. 15 (1000 ms, i.e. 1 s), the front trim carriage 151 is in the waiting position. The rear trim carriage 152 has reached its maximum speed, which is slightly higher than that of the infeed conveyor 31. In Fig. 16 (1100 ms), the front trim carriage 151 is still in the waiting position, the air blast nozzles are now off and the rear trim carriage 152 has reached its maximum speed, which is slightly higher than that of the infeed conveyor. Finally, in Fig. 17 (1150 ms), the front trim carriage 151 is still in the waiting position; the rear trim carriage 152 now begins to slow down and the gripper 137' is pivoted away from the product. The front and rear trim carriages 151, 152 now move together to the position shown in Fig. 5 to begin the next trim removal cycle.

Structural features

Reference is now made to Fig. 20, in which the reference numeral 148 is in the middle of the illustration and here too designates the discharge pipe, i.e. the pipe through which the trim rings are removed from the rails 147 (see the middle part of Fig. 3). The trim rings blown off with the air blasts 149 can be fed into a collecting container for return to the pulp production or other disposal. When using negative pressure, a separating device such as a cyclone is normally connected between the pipe 148 and the receiving device. On either side of the pipe 148 in Fig. 20 are the front and rear trimming carriages 151 and 152, respectively. These carriages are generally rectangular and are provided with guide wheels at the four corners as at 158 (carriage 151) and 159 (carriage 152); the wheels are only marked in the bottom left corner. The guide wheels 158 can be seen in Fig. 19; they run on rails 160; see also Figs. 18 and 20.

As shown in Fig. 20, the carriages 151, 152 are each provided with a swivel motor 161 or 162, which swivels the grippers 137, 137' into the raised or lowered position. For example, in Fig. 5 the grippers 137 are shown raised and in Fig. 6 lowered, and accordingly the grippers 137' are shown raised in Fig. 9 and lowered in Fig. 10.

The rotary actuator is also shown in the center of Fig. 19. A suitable device is available from Parker Fluid Power Co. of Wadsworth, Ohio, V. St. A., under the designation "Rotary Actuator Model PV33D." The rotary actuator has projecting rods as at 163 (see Fig. 19) which carry an arm 164 to which a resilient gripping element 165 is attached. The Gripping member 165 may be made of a soft compressible foam material so that it can conform to the contour of the shorter product article - e.g., toilet paper, folded facial tissues, etc.

As further shown in Fig. 19, a base frame generally designated 166 supports the rails 160 and thus the carriages 151, 152. The base frame is raisable and lowerable relative to the feed conveyor generally designated 31 (see Fig. 19, bottom center) to accommodate changes in product, diameter and height. The base frame 166 is coupled to an indexing drive 167 - see Fig. 19, top center and Fig. 18, top left. The upstream and downstream ends of the base frame 166 are stabilized with a linkage arrangement generally designated 168 and best seen in Fig. 18, top, where it runs from left to right. The rod is designated 169, the rod links at each end of the rod 169 are designated 170.

In order to move the slides 151, 152 horizontally with the speed profile of Fig. 4, the servo motors 171 and 172 are provided (see Fig. 20 above). The servo motor 171 is coupled to a cross shaft 174 via a 90º angle drive 173, and the servo motor 172 is coupled to a cross shaft 176 via a further 90º angle drive 175. The cross shaft 174 determines the position of the slide 152.

WORKING METHODS

The process for handling elongated sections of multi-layer material (Fig. 1) and trim pieces has the following steps:

(a) cutting the elongated sections transversely (as at 36 in Fig. 3) into products of smaller length, each elongated section and each product having an upstream and a downstream end and trim pieces at both section ends;

(b) the supported forward guidance (42, 31) of each elongated section and product article on a horizontally extending path (P); this much is known from the prior art. The invention further comprises the following steps:

(c) grasping (137) and advancing (151) the most upstream product item of each elongated section while simultaneously

(d) removing the trim piece (TT) adjacent to the most upstream product by a generally upward movement (149) and also

(e) removing the trim piece (TL) adjacent to the downstream product by a generally upward movement (149).

FIGURE CAPTIONS

Fig. 1 Prior Art State of the Art

Fig. 2 Prior Art State of the Art

Fiq. 44 Velocity Time

Claims (11)

1. Method for handling elongated sections of multi-layer material and trim pieces by advancing an elongated section of the material supported on a horizontally running path (P) and cutting the material in the transverse direction into product items of smaller length with at least one upstream product item, one downstream product item, one upstream trim piece adjacent to the upstream product item and one downstream trim piece adjacent to the downstream product item, characterized in that the upstream product item is grasped (137) and advanced (151) while the trim piece (TT) adjacent to the upstream product item is removed with an upward air stream, and also grasping the downstream product item while the trim piece (TL) adjacent to it is removed with an upward air stream removed. 2. A method according to claim 1, wherein the upward air flow is generated by applying an upward air blast (149) from beneath the trim pieces. 3. A method according to claim 1, wherein the upward air flow is generated by applying a negative pressure to the trim pieces. 4. Method according to claim 3, in which the upward air flow is generated by directing a blast of air (149) at the trimming pieces from below when they are subjected to negative pressure. 5. Method according to claim 1, wherein when gripping and moving forward the upstream product object, it is moved at a speed (157) which is higher than the feed speed (156) of the elongated section. 6. A method according to claim 1, in which a discharge pipe (148) is arranged above the web and an air blast device (149) is arranged below the web in general alignment with the discharge pipe and a carriage arrangement (151, 152) is arranged so as to be movable into a closing relationship with the discharge pipe, the carriages (151, 152) being moved over the product articles at the trim pieces so that the upstream and downstream product articles cannot move in a generally upward direction under the influence of the air blast device. 7. The method of claim 1, wherein the elongated section is a master roll of wound material and the shorter product items are retail size rolls. 8. The method of claim 1, wherein the elongated portion is a stack of folded web material. 9. Device for handling elongated sections of multi-layer material and trimmings which, when the elongated sections are cut open in the transverse direction, are to be cut into shorter product items, the elongated section and the product items each having an upstream and a downstream end and being guided forwards in a supported manner along a horizontal track also having an upstream and a downstream end, and the device comprising a frame, a trough arrangement (42) on the frame, which partially forms the horizontal track (P), a ram device (32) which is operatively associated with the trough arrangement in such a way that it lies against the upstream end of an elongated section and pushes it towards the downstream end of the track, and a saw blade device (36) which is movably arranged on the frame in order to cut the elongated sections into a plurality of product items and upstream and downstream trimming pieces, characterized by a carriage device (151, 152) associated with the product items and equipped with grippers, which is mounted on the frame above the track and at the downstream end of the trough arrangement to grip the product article adjacent to each trim piece, by an air flow device (148, 149) associated with the grippers and by a control (150) which selectively actuates the air flow device so that the latter generates an air flow which guides the trim pieces on the adjacent product articles upwards out of the track. 10. Device according to claim 9, in which the air flow device has a discharge pipe (148) with a trimmings receiving end and a trimmings discharging end and a trimmings removing device on the latter. 11. Apparatus according to claim 9 or 10, wherein the air flow device (148, 149) comprises an air jet device (149) under the web, a negative pressure generating device above the web, or both of these devices.