GB2024081A - Scrap removal means for rotary punching machines - Google Patents

Abstract

A rotary punching machine of the kind including a knife cylinder 35 equipped with punch blades 37 on its outer peripheral surface, an anvil cylinder 34 having a support layer against which the blades act so as to punch out workpieces from sheet fed between the two rotating cylinders, and a scrap knockout means wherein each of the punch blades is formed with a cut or slot therein, and a scrap knockout lever 42 extends through the cut or slot to be thereby restricted in its upward and downward motion, one end of the knockout lever being a free end located in the space defined by the punch blade and the other end being mounted adjacent said punch blade so that, in operation, scrap pieces formed during punching can be removed by outward movement of said free end of the lever. Such a construction ensures positive and efficient removal of said scrap pieces. <IMAGE>

Description

SPECIFICATION Scrap removal means for rotary punching machines This invention relates to means for removing scrap pieces formed during punching of sheet material such as corrugated board, particularly in rotary punching machines.

Punching sheet material such as corrugated board to desired shapes is usually carried out by rotary punching machines. Fig. 1 shows schematically a rotary punching machine of conventional design. Corrugated board sheets 1 stacked on a feed table 3 are forced, one by one, into a pair of feed rolls 4 by a reciprocating kicker 2. Rotation of these rolls causes the sheets to be fed in succession to a punching zone 5 and thereafter a scrap removal zone 6; thus the desired shapes are punched out from the sheets in the zone 5 and the residual scrap pieces are removed in the zone 6.The punching zone 5 normally comprises a knife cylinder equipped with a punch on its outer peripheral surface and adapted to rotate in a given direction at a predetermined speed, and an anvil cylinder located to mate with the knife cylinder and run counter to but at the same speed as the knife cylinder, the anvil cylinder being equipped with a member or layer on its outer peripheral surface against which the punch is to be pressed. Each sheet of corrugated board is punched (sheared) between the blades of the punch and the bladereceiving layer. Punching in this punching zone 5 is normally accomplished by either of two methods. One is referred to as the hard cut method because, as illustrated in Fig.

2(A), the sheet is cut by planar blades 7 which are urged against a blade-receiving member 8 of steel. The other method is referred to as the soft cut method which uses a combination of saw blades 10 and a rubberlined blade-receiving member 12, as shown in Fig. 2(B). In the hard cut method, the surface of the blade receiving member, e.g. in the form of an anvil cylinder, is surface hardened so as not to be damaged by contact with the edges of the planar blades 7. In the soft-cut method, the edges of the saw blades 10, which bite into the rubber layer 11 of the anvil cylinder 1 2 to cut off each sheet of corrugated board, will naturally damage the outer peripheral surface of said rubber layer.

This, in turn, will cause the saw blades 10 to be dulled, resulting in incomplete shearing of the corrugated board. For this reason, it is a known practice to vary slightly the ratio of rotation of the knife cylinder 9 to that of the anvil cylinder 1 2 slightly, for example 49 : SO, as well as to arrange for the anvil cylinder 1 2 to shift its position axially with respect to the knife cylinder 9 so that the edges of the saw blades 10 may uniformly contact as wide an area of the outer peripheral surface of the rubber layer 11 as possible, instead of a limited, unchanged surface portion.

Whichever method of punching is used, scrap pieces left from the punching operation are not completely severed from the remainder of the sheet but are left behind in the punched sheet. This necessitates an additional operation for scrap removal.

Generally, there are two known methods for scrap removal. In one method, as shown in Fig. 1, a scrap removal zone 6 separate from a punching zone 5 is provided. The other method is referred to as a single-unit method in that the punching zone 5 accomplishes both punching and removal of the resulting scraps. An arrangement usually used for simultaneous punching and scrap removal is shown in Fig. 3. This comprises kickoff sponge rubber or other suitably resilient pads 1 2 and 1 3 for separately forcing out from the sheet the punched workpiece and the scrap pieces, respectively.These pads are attached to the surface of a punch 14 mounted on the knife cylinder and are of suitably selected height and hardness to attain optimum amounts and rates of kickoff, thereby enabling the punched work 1 5 and the scrap pieces 1 6 to be separated as soon as they are forced out of the sheet fed therethrough.

However, existing single-unit arrangements involve the following difficulties: (i) Because of the high feed rate of the sheets (usually in the range of about 2-3 m/sec), the separation of each punched work 1 5 and the resulting scrap pieces must be completed within a very short period of time.

(ii) Particularly in the case of corrugated board sheets, the greater thickness of these (generally about 3 to 8 mm thick) compared with ordinary paper results, as indicated in Fig. 4, in a large relative out-of-phase distance S necessary for separating each punched work 15 and the scrap pieces 16.

(iii) As shown typically in Fig. 5, a corrugated board sheet consists of a front lining 17, a rear lining 18, and a fluted sheet 1 9 separating the two flat sheets. Consequently, due to the spaces between the component parts of the board, the sheared edges of the board tend to overlap and be caught up in each other, as shown by the reference B in Fig. 5.

(iv) Particularly with the soft-cut method employing saw blades 10, as shown by the reference Cin Fig. 6, the sheared edges of the work and therefore of the scrap pieces (shown hatched) tend to be serrated so that the components parts of the corrugated board can easily be caught up in each other.

These difficulties combine to hamper the separation of scrap pieces from punched sheets particularly of corrugated board and particularly where, as shown in Fig. 6, the sheet is so sheared and punched as to form end scrap pieces 20 on the leading end facing the direction Xof delivery and to form slot or hole scrap pieces 21.

Fig. 7 shows a typical prior art arrangement of a scrap removal zone separate from the punching zone (Fig. 1). An upper cylinder 22, adapted to be driven in the same direction and at the same speed as the knife cylinder of the punching zone, carries a scrap kickoff block 23 secured by suitable fastener means to the outer peripheral portion of the cylinder corresponding to the point where scrap pieces 16 are to be removed passes. Opposite to the upper cylinder 22 is located a lower cylinder 24, which is covered with a layer of elastic and flexible material such as soft sponge rubber 25, so that the scrap pieces 1 6 may be forced by the kickoff block 23 into the sponge 25 for subsequent removal.With this dual-unit type arrangement, so called because the punching and scrap removal zones are provided as separate units, it is necessary to deliver the punched sheet and the resulting scrap pieces together, and therefore in an incompletely separated state, to the scrap removal zone. However, the punched sheet and the scrap pieces once trapped in the space surrounded by the blade edge in the punching zone naturally tend to separate from each other on their way to the following zone. This frequently results in unwanted dropout of the scrap pieces during the transfer between the two zones and also in an inefficient use of the scrap removal zone.

A seemingly effective countermeasure might be to provide, as indicated by the reference D in Fig. 6, nicks 26 so that the punched work and the scrap pieces are not completely separated during punching. However, such a measure is not practical because the scrap pieces and the remainder of the sheet partly joined by the nicks 26 would be rather difficult to separate subsequently for scrap removal.

Apparatus of the dual-unit type, comprising separate zones for punching and scrap removal, is costly and needs considerable space for installation. In addition, assembly of the apparatus may require up to twice as much labour and time as for the singie-unit type.

An object of the present invention is to provide means for positively removing scrap pieces during punching, which permits the use of a single-unit punching machine so as to avoid the need for a large installation space, high cost, or much time and labour for assembly needed for a dual-unit type, while overcoming all or at least many of the disadvantages of known single-unit machines.

According to the invention, scrap knockout means are provided for use with a rotary punching machine which includes a knife cylinder equipped with punch blades on the outer peripheral surface, and an anvil cylinder having a layer against which the blades are forced for punching out a workpiece fed between the two rotating cylinders, characterized in that a scrap knockout lever is arranged to engage with a cut or slot formed in a punch blade of the machine to be thereby restricted in its upward and downward motion, one end of said knockout lever being a free end located in a space defined by said punch blade and the other end being mounted adjacent said punch blade, the arrangement being such that scrap pieces formed by punching can be removed by the outward movement of said free end of said lever.

The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: Figure 1 is a schematic general view of a conventional rotary punching machine; Figures 2(A) and 2(B) are sectional views of two different punching arrangements for rotary punching machines; Figure 3 is a detailed sectional view illustrating one prior art method of separating the scrap pieces formed during punching; Figure 4 is a sectional view taken along iine A-A of Fig. 3; Figure 5 is a sectional view of the sheared ends of punched work and scrap pieces formed by the arrangement of Fig. 3; Figure 6 is a plan view of punched work formed by the arrangement of Fig. 3, indicating typical relationships between the punched work and resulting scrap pieces;; Figure 7 is a detailed sectional view illustrating another prior art method of separating the scrap pieces formed during punching; Figure 8 is a schematic general view of a rotary punching machine embodying the invention; Figure 9 is an enlarged sectional view of the punching zone of the machine shown in Fig. 8; Figure lOis an enlarged plan view, in section, of the punch blade and associated parts of the punching zone of Fig. 9; Figure 11 is a sectional view taken along line G-G of Fig. 10; Figure 12 is a plan view of a slot formed in the punch blade support of the punching zone; Figure 13 is a fragmentary view of the punch blade; Figure 14 is a sectional view of a modification to the embodiment shown in Figs. 8 to 13, with two scrap knockout means instead of one installed in the space surrounded by the punch blade; Figure 15 is a view similar to Fig. 13 but showing a modified form of the punch blade; and Figure 16 is a view similar to Fig. 11 but showing a section through the modified form of the blade shown in Fig. 1 5.

The invention will now be described in detail in connection with an embodiment thereof illustrated in Figs. 8 to 1 3. A number of sheets, for example, of corrugated board 31 are fed, one by one, from the bottom of a stack on a feed table into a pair of feed rolls 33 by a feed kicker 32 which latter is reciprocated by suitable drive means. The feed rolls 33 coact to force each sheet of corrugated board 31 positively into a punching zone. The punching zone is defined by a knife cylinder 35 having a punch 36 mounted thereon, and an anvil cylinder 34. The sheet of corrugated board 31 is punched to a desired shape by the punch 36 and the anvil cylinder 34.

As shown in Fig. 9, the knife cylinder 35 is hollow and is rotated in a selected direction at a predetermined circumferential speed by suitable drive means not shown. The anvil cylinder 34, which is arranged in contact with the knife cylinder 35, is rotated contrary to, but at the same circumferential speed as the knife cylinder. The punch 36 is of the following construction. A blade support layer 39 attached around the knife cylinder 35 is formed with circular slots 39' (see Fig. 12), in each of which a punch blade 37 is press fitted. Each blade 37 is surrounded by a piece of kickoff sponge 38 or the like secured to the blade support layer 39.A suitable number of such punch blades 37 and sponge pieces 38 are disposed over the blade support layer 39, at strategic points circumferentially and axially thereof depending upon the contour, size, and intervals of the portions of the work to be punched out of the board. The knife cylinder 35 and the blade support layer 39 have corresponding through holes 35a formed at right angles to their axes and at appropriate intervals (e.g. about 50 mm apart) on the outer peripheries.

Each punch blade 37 is formed with a square cut 37' (see Fig. 13) made in the portion half set into the blade support layer 39.

A scrap knockout lever 42 extends through the cut 37' of each blade 37 and terminates with a free end in the space surrounded by the blade 37. The other end of the lever is elastically mounted in and engaged with a recessed part of a fulcrum member 43 (see Fig. 11). As shown, each scrap knockout lever 42 is arranged to turn up and back about the end where it engages the recessed part of the fulcrum member 43, which member, in turn, is fixed to the blade support layer 39 by a fastener 44. A hollow push cylinder 41 (see Fig. 9) is housed in the knife cylinder 35, with its centre off-set from that of the latter, and this eccentric cylinder rotates in the same direction and at the same angular velocity as the knife cylinder 35.

Into each superposed set of the through holes 35a is loosely fitted a radially extending push rod 40 so as to be capable of endwise movement. A plurality of such push rods are arranged at axially and circumferentially spaced positioned of the knife cylinder 35, and correspond to the number and locations of scrap knockout levers 42 provided.

Each push rod 40 is designed as to move with the revolution of the knife cylinder 35, and is forced by the eccentric cam action of the push cylinder 41 to work as follows.

When a given knockout lever is in the region E(see Fig. 9), the associated push rod 4 is in contact, at its inner end, with the outer surface of the push cylinder 41, the outer end of the rod in its through hole being sunken from the outer surface of the blade support layer 39. As the knife cylinder 35 revolves the knockout lever approaches the region F, and the push rod 4 is urged radially outward, with its outer end gradually emerging out of its through hole to project from the surface of the blade support layer 39. This movement of each push rod 40 is effected by suitably choosing the length of the rod and the magnitude of eccentricity of the push cylinder 41.

The push rods 40 are made of lightweight material, e.g., a synthetic resin, and are smoothly finished on the surface so that they can easily slide endwise in their through holes 35a. As it projects from the surface of the blade support layer 39, each push rod 40 contacts and pushes its respective scrap knockout lever 42 away from the surface of the blade support layer 39.

The punch 36 is set in place in the following way. Firstly, each punch blade 37 is formed with a square cut 37' of predetermined width land height h(see Fig. 13).

Next, for each blade 37, pairs of holes 39" (see Fig. 1 2) are drilled in the blade support layer 39 in such a manner that the centre-tocentre distance of the resulting holes of each pair is the dimension lof a predetermined value. A jig-saw usually employed for such purposes is introduced into either hole, and then the two holes are connected by the circular slot 39' referred to hereinbefore to receive a punch blade 37. Following this slotting of the blade support layer 39, the blade 37 is force fitted in the slot 39' and is securely set in position. Then, from the distance m between the centres of a scrap piece to be formed and its respective push rod 40, the length n of the associated scrap knockout lever 42 is suitably chosen, and the fulcrum member 43 is fixed at an end of the length n by the fastener 44.The square cut 37' of the punch blade 37 is such that its width I is greater than the width I' (see Fig. 10) of its knock-out lever 42 and its height h provides an ample allowance for the knockout lever 42 to be moved away from the surface of the layer 39 by endwise movement of the push rod 40. The reference 38 indicates a kickoff sponge sponge for forcing a punched work out.

With the construction so far described, the embodiment operates in the following man ner. Each sheet of corrugated board 31 fed by the feed rolls 33 passes between the knife cylinder 35 and the anvil cylinder 34. During its delivery (in the direction of the unreferenced arrow shown in Fig. 8), the sheet is punched by the punch blades 37 of the punch 36 mounted on the knife cylinder 35, against the anvil cylinder 34. The punched work is forced out by the elasticity of the kickoff sponge pieces 38 toward the next station for further fabrication.

Each scrap piece formed by punching is carried by that punch blade 37 revolving with the knife cylinder 35. As the scrap piece approaches the region i, the associated push rod 40 is gradually lifted by the eccentric cam action of the push cylinder 41, so that the outer end of the rod projects beyond the surface of the blade support 39 on the knife cylinder 35, thereby urging the respective scrap knockout lever 42, and thence the scrap piece, outwardly. With further rotation of the knife cylinder 35, the scrap piece reaches the region F; where it is released from the blade and falls onto a scrap conveyor (not shown) for delivery to some external collection point.

Before the punch unit 36 returns to the region Ewith the rotation of the knife cylinder 35, the push rod 40 is reset axially to its initial position, and hence the scrap knockout lever 42 is freed to return and rest on the surface of the blade support layer 39. Although the knockout lever 42 itself does not have means for returning it to its rest position, it does return as it is forced against the blade support layer 39 by a newly formed scrap piece from the next punching operation in the region E The cycle just described is repeated to punch successive sheets of corrugated board and to remove the scrap pieces formed.

While the cut 37' in this embodiment has been described (and illustrated in Fig. 13) with a square (or rectangular)-cut open at the lower edge of the blade 37, it may be of other forms. For example, it may be a rectangular closed slot (see Fig. 15) formed at a suitable height in the blade 37, of the required width /. In this case, an assembly problem may arise in regard to the insertion of the scrap knockout lever 45 through the slot 37'. However, this may be achieved, as indicated in Fig. 16, by dividing the lever into a scrap knockout pad 45 and a lever shank 46 and joining them together by bonding or other means after assembly of the punch components.

Where the circular punch blade 37 is too large or elongate in shape, two or more cuts or slots may be formed, with respective scrap knockout levers 42, as shown in Fig. 14.

Also, while the scrap knockout lever in the above embodiment has been described as acuated by the push cylinder and the push rod, other actuation means may be provided.

For example, the knockout lever itself may provide the elasticity necessary to raise it from the surface of the blade support layer 39. In this case, during punching, it will be forced against the surface of the support layer 39 by the nip pressure exerted between the anvil cylinder 34 and the knife cylinder 35. As it is released from the nip pressure, the lever will curl up elastically and thereby rise from its support surface to knock out the scrap piece from the punch blade. Alternatively, the knockout lever may be pneumatically actuated, with a suitable portion on the inner side of the lever subjected to an air pressure whereby to bias the lever away from the blade support surface 39.In other modifications, the push rod 40 may be timed in operation to slide hydraulically, or the push cylinder 41 may be replaced by a cam of an appropriate profile, and a cam follower attached to the inner end of the push rod, so that the push rod may be guided in its motion by the cam follower in sliding contact with the cam.

In accordance with this invention, as has been described above, each scrap piece from the sheet material formed during punching is completely separated from the punched work and is positively removed from the space surrounded by the punch blade, this being effected by the outward movement of knockout levers from the blade support surface.

Moreover, because each scrap piece is knocked out at a predetermined point, there is no problem of random scattering and the scrap pieces can be easily delivered out of the machine. As discussed hereinbefore, machines of the so-called single-unit type in which the punch blade punches out work of a desired shape and, at the same time, knocks out scrap pieces formed during punching, is less costly than the conventional dual-unit type, and it does not require a large space for installation. The present invention enables the use of this type of machine without the disadvantages normally associated therewith.

Claims (7)

1. Scrap knockout means for a rotary punching machine of the kind which includes a knife cylinder equipped with punch blades on the outer peripheral surface, and an anvil cylinder having a layer against which the blades are forced for punching out a workpiece fed between the two rotating cylinders, characterized in that a scrap knockout lever is arranged to engage with a cut or slot formed in a punch blade of the machine to be thereby restricted in its upward and downward motion, one end of said knockout lever being a free end located in a space defined by said punch blade and the other end being mounted adjacent said punch blade, the arrangement being such that scrap pieces formed by punching can be removed by the outward movement of said free end of said lever.

2. Scrap knockout means according to Claim 1, characterized in that said knife cylinder is equipped with push rods, which are radially arranged and each of which is adapted to move endwise to cause said outward movement of the scrap knockout lever.

3. Scrap knockout means according to Claim 2, characterized in that a push cylinder is eccentrically located within said knife cylinder, and the inner ends of said push rods are actuated by relative movement between said push cylinder and said knife cylinder to produce said endwise movement.

4. Scrap knockout means according to Claim 1, characterized in that each said scrap knockout lever is imparted with elasticity so that, during operation of the punch machine, upon release of a nip pressure between the two rotating cylinders it acts to create said outward movement of its free end by its own tendency for elastic recovery.

5. Scrap knockout means according to Claim 1, characterized in that each said scrap knockout lever has means associated therewith for creating an air pressure for causing outward movement of its said free end.

6. Scrap knockout means constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figs. 8 to 13, or modified as described with reference to Fig. 14, or 15 and 16 of the accompanying drawings.

7. A single-unit rotary punching machine equipped with scrap knockout means according to any one of the preceding Claims.