GB2171050A - Method and equipment for cyclically treating a travelling web - Google Patents

Abstract

In a method of cyclically treating a travelling web eg for printing, cutting and/or edge preforming boxes or the like produced from a continuous cardboard web 2 the treatment of the web is obtained by contact between tools 3 on a die 1 and the web surface, the tools being rotated at a velocity synchronized with that of the travelling web while the tools are pressed on this web but when cleared therefrom are caused to move continuously along a closed-loop path at a speed asynchronous with respect to the linear velocity of the web. There may be a plurality of tools mounted on a single drum, or as in Fig. 2, the tools may be mounted on an endless belt 5 passing around the drum 1 and a roller 6. <IMAGE>

Description

SPECIFICATION Method and equipment for cyclically treating a travelling web This invention relates to a method of cyclically treating a travelling web and to an equipment for carrying out this method. The invention is applicable more particularly to industries wherein materials are processed in the form of continuous webs, as in the paper, pasteboard and cardboard industry, and also in printing plants.

At present certain industries utilize as raw materials products in the form of continuous webs or bands. To simplify the handling, the web is treated throughout its length and then cut into separate sheets or sections having a predetermined size for obtaining the final product.

This mode of operation is current practice notably in the cardboard industry wherein cardboard is produced continuously in large amounts and subsequently cut and printed during separate steps for manufacturing for instance packing boxes.

According to the size of the final box to be obtained, the edges are preformed and notches and impressions are made therein according to a predetermined cyclical rhythm.

These cyclical treatment steps may be performed according to various methods, the first method consisting in stopping the cardboard section to be treated under a tool supporting die, operating this die and then, when the treatment is completed, feeding the cardboard web by one step and repeating the operation.

This method is objectionable in that it requires a discontinuous movement of the web, thus preventing the positioning of the treatment machine in series with the cardboard manufacturing machine feeding the products continuously to the treatment machines.

A second known treatment method which lends itself to a continuous operation consists in utilizing a tool supporting die secured to the cytindrical surface of a drum. This drum is driven for rotation at a constant speed in synchronism with the linear velocity of the web, so that the web can be treated periodically at spaced intervals corresponding to the diameter of the tool supporting drum.

This second method is now in general use, but as a rule it is carried out separately so that the cyclic treatment means are not disposed downstream of the cardboard producing machine or the like.

Besides, the geometric properties of the drum make it suitable for performing a welldefined type of treatment so that any change brought in the side of the desired end product involves necessarily a corresponding change in the drum size. This inconvenience is not found in the first above-mentioned method in which a one-step feed of the web is independent of the movement of the tool supporting die.

It is one object of the present invention to provide a method of cyclically treating a travelling web, such that as the web is caused to travel for example at the uniform linear speed obtained at the output end of a cardboard producing machine, well-defined sections of the travelling web can be treated at adjustable space intervals.

Thus, the tool means become universal irrespective of the selected pitch, so that it is possible to contemplate a range of products without any increment in the manufacturing costs.

On the other hand, the means for cyclically treating a travelling web according to the present invention may be disposed at the output end of a cardboard manufacturing machine, so that a fully combined production line can be obtained without resorting to any intermediate additional operation.

It is another object of the present invention to provide an equipment for cyclically treating a continuously travelling web wherein a plurality of tool holders are disposed in series and operate independently of each other according to an adjustable pitch, thus permitting of obtaining an end product which can be fully adapted to requirements.

Other features and advantages of the invention will appear as the following description proceeds with reference to exemplary and specific forms of embodiment.

The method of cyclically treating a continuously travelling web, notably for printing or impressing, cutting or preforming the edges of boxes or other articles from a continuous web of cardboard by the pinpoint contact of tools assembled on a tool supporting die, is characterized in that: -the tools are moved at a speed synchronous with the linear speed of the web, -the tools are set in pinpoint contact with the web surface, the tools are cleared while preserving the continuity of their movement along a closed path, and their speed is desynchronized with respect to the web speed, and -the treatment cycle is repeated.

The equipment for cyclically treating a travelling web, notably for printing, cutting or pre-forming the edges or boxes or other shapes from a continuous web of cardboard, which comprises at least one tool-supporting rotary drum disposed across the web and adapted to process said web by contact, is characterized by the fact that the tools are assembled on an operative circular sector of the drum, and that this drum is driven for rotation in synchronism with the linear motion of the web when the operative circular sector engages said web and in asynchronism during the remaining part of the rotation.

The invention will be better understood as the following description proceeds with refer ence to the accompanying drawing.

Figures la and lb illustrate diagrammatically the cylindrical treatment of a continuously travelling web, Figure 2 illustrates a typical form of embodiment of a tool carrier, Figure 3 shows a typical form of embodiment of an equipment for cyclical treatment, intended more particularly for preforming edges and cutting the cardboard, Figure 4 illustrates cyclical treatment means equipped with a plurality of tool carrying drums arranged in series, and Figure 5 illustrates a typical application of the cyclical treatment equipment for obtaining printed panels of different configurations.

The cyclical treatment method of the present invention is intended and adapted more particularly for the treatment of continuously travelling webs. However, as will be seen from the following description, the method of this invention is also applicable to discontinuous webs comprising a sequence of panels disposed for example seriatim.

The method of the instant invention is applicable to sheets and webs irrespective of the material employed for making them. However, to facilitate the understanding of the invention the following description refers to the cardboard industry in which the treatments to be effected are mainly printing, cutting or preforming the edges of boxes or other articles from a continuous cardboard web.

According to the method of the present invention the web is caused to travel continuously as in the case of a cardboard web issuing from a cardboard manufacturing machine, so that the manufacture can be combined on a single production line without resorting to any intermediate operation. The travelling web is treated by pinpoint contact between tools and the web surface. The tools may be cutting, preforming or relief printing, tools, operating for example either separately or in combination. The various tools are assembled on a common supporting die.

According to the present invention, the tools are driven at a peripheral velocity synchronous with the linear velocity of the travelling web. Then, the tools are pressed in pinpoint contact against the web in order to carry out the desired treatment operation, and upon completion of this operation the tools are raised off the web while preserving the continuity of their movement along a closedloop path. The continuity of the tool movement is advantageous in that the method is thus applicable to die and tool means constituting a considerable mass since no sudden or fierce acceleration is required. On the other hand, this closed-loop path permits of performing a cyclical treatment since during its movement the tools are caused to periodically engage the travelling web.

However, an asynchronism between the tool speed in relation to the web speed is obtained at the end of the treatment operation or step when the tools have been raised off the web.

This de-synchronizing is essential for it permits of varying the periodicity and therefore the pitch of the treatment performed on the travelling web. By accelerating the tool speed, the treatment frequency is increased and consequently the distance between the treated areas or sections of the web is shortened. On the other hand, reducing the tool speed at the end of the treatment operation or step will slow down the treatment frequency, thus lenghtening the pitch or distance between successive treated areas or sections of the travelling web. The cyclical method of this invention comprises the above-listed sequence of steps or operations.

From the foregoing it will be clearly apparent that with the method of the present invention it is possible to make products of different size without changing the geometrical properties of the die. In other words, with this method it is possible to obtain a complete range of products by using a single-tool drum.

According to the treatment method of the present invention, the tools are secured to a form and the latter is pressed tangentially against the travelling web. With this specific arrangement it is possible to cause the various tools to engage the web sequentially and tangentially for imparting the desired treatment thereto.

The method of cyclically treating a travelling web according to the present invention may be carried out by using an equipment of the type illustrated diagrammatically in Figs. 1a and 1 b. In this case, the tool supporting die has the form of a drum 1 disposed transversely in relation to the direction of travel of the web 2. The tool supporting drum 1 is driven for rotation and adapted to perform a treatment by contact as shown diagrammatically by a hatched area 4 in Figs. 1a and 1b.

According to the present invention, the tools 3 are assembled on an operative sector of the tool supporting drum 1.

Fig. la shows the cyclical treatment equipment during its operation, that is, when the tools 3 engage the web 2. In this case, the circular movement of the drum 1 is synchronized with the linear velocity of translation of web 2. In fact, it is absolutely necessary that the tangential or peripheral speed of drum 1, which corresponds to the speed of tools 3, be identical with the linear velocity of translation of web 2, so that the tools 3 can perform a pinpoint treatment on the web 2.

Fig. 1b illustrates the de-synchonizing steps, i.e. when the tool-supporting operative area of drum 1 is no more in contact with the travelling web 2. In this case, there is no contact whatsoever between the drum 1 and web 2, and the drum may be driven with an asynchronous circular motion. According to the se lected synchronous speed, it is possible to adjust the periodicity of the treatment performed by the operative segment or arc 3 of drum 1.

Thus, by using a same tool supporting drum 1, it is possible to treat a travelling web 2 according to different sizes with a gradual change from one size to another.

The treatment equipment of the present invention may be improved for example by fixing on the peripheral surface of the tool supporting drum 1 a plurality of sectors constituting operative areas obtained by adding different tool carrying dies independent from one another. The tool supporting drum arrangement illustrated in Figs. 1a and 1b may also be contemplated without necessarily fixed the tools on the peripheral surface of drum 1, as illustrated in Fig. 2. In this case, the tools 3 are disposed on an endless belt 5 interconnecting the drum 1 and a second or return cylinder 6.The movement of the tool supporting belt 5 is the same as that contemplated in the preceding example, in that the linear velocity of this belt is synchronized with the travelling speed of the web 2 when the operative area 3 constituting or supporting the tool means engages the web 2; on the other hand, when the operative phase is completed, the linear velocity of belt 5 becomes asynchronous and is set as a function of the periodicity of the treatment to be applied to the web 2. This arrangement is particularly advantageous when the pitch of the treatment to be applied to the travelling web 2 is relatively great. In fact, in this case the required asynchronous rotary motion makes is compulsory to reduce considerably the angular velocity of the tool supporting drum.In order to avoid the necessity of attaining excessive deceleration and acceleration figures during this asynchronous phase, the inoperative sector, corresponding to the sector complementary to the operative sector 3 of the drum, must have sufficient dimensions. As a result, in this case the tool supporting drum must have a very large diameter leading to excessive overall dimensions most likely to impair the equipment.

By utilizing the principle of an endless belt 5 interconnecting a return cylinder 6 and a tool supporting tool 1, it is possible to constitute an inoperative section complementary to the operative section 3 without induly increasing the overall dimensions of the equipment.

For carrying out certain specific treatments such as cutting a cardboard web or preforming the edges of a cardboard web, it is advantageous, during the treatment operation, to dispose of support means for the cardboard web. A typical example of such support means is illustrated in Fig. 3.

In this Fig. 3, showing by way of example the treatment of a cardboard web 2 by means of a tool supporting cylinder 1 comprising on its cylindrical or peripheral surface an operative section 3, the support 7 consists of a cylinder 7 having a peripheral velocity sunchronous with the linear speed of the cardboard web 2 so as to provide a slipless tangential contact. According to a preferred form of embodiment of cylinder 7, the latter comprises on its outer periphery a lining 8 of suitable resilient material such as a suitable polyurethane compound. The dimensions of this counter-cylinder 7 are moderately important, provided that its peripheral velocity be substantially equal to that of the travelling web 2 in order to constitute a tangential support enabling the cutting blades 3 to penetrate into the surface of the cardboard web 2.The counter-cylinder 7 may if desired by rotatably driven by simply causing this cylinder to engage the travelling web 2, and in this case the desired synchronism is obtained automatically.

Fig. 4 illustrates an improved cyclical treatment equipment according to the present invention, which comprises a sequence of operative stations. In this example the number of these operative stations is limited to two, but it is obvious that a greater number of such stations may be contemplated within the scope of the invention. The tool supporting drums 9 and 10 are rotatably driven independently of each other in synchronism with the linear velocity of the web 2 when the operative sections 11 and 12 of said cylinders are caused to engage the top surface of web 2, and asynchronously when the inoperative sections of tool supporting drums 9 and 10 contact the web surface.

Each tool supporting drum may apply a cyclical treatment 13 and 14. However, it is highly desirable that an accurate timing be obtained between the operative sectors 11 and 12 of the tool supporting drums 9 and 10 in order properly to position the areas 13 and 14 treated by drums 9 and 10, respectively.

This subdivision of the treatments applied by drums 9 and 10 permits a considerably wider variation in the finished product. Thus, for instance, if one drum of the pair is used for cutting the web while the other is used for printing the web, it is possible to change continuously the size of the finished product by adjusting the cyclical rotary motion of the cutting drum and to position the printing, irrespective of the selected size, for example centrally of, or intermediate, the cuts, by adjusting the rotary motion of the printing drum.

Fig. 5 illustrates an equipment for performing a cyclical treatment according to the present invention, which is designed for obtaining printed carboard sheets or panels 15. The treatment equipment according to the present invention is fed at a constant rate with a cardboard web 2 and in the selected example the tool supporting drum 1 comprises two tangent blades 16 and 17 adapted to cut sheets 1 5 from the web. To facilitate the cutting operation a counter-cylinder 7 provided on its per ipheral surface with a lining of resilient material is used. Moreover, between the cutting blades 16 and 17 the tool supporting drum 1 is provided with a printing plate 18 adapted to print a design 19 on the sheets 15.

In the selected example the size of the cut cardboard sheets 15 may be changed or varied continuously while constantly using the same tool supporting drum 1, with a cenral positioning of the printing 19.

In fact, by varying the angular velocity of tool supporting drum 1 during the pass age of the cardboard web 2 under the angular sector separating the blades 16 and 17 from he printing plates 18, the periodicity of the cuts and consequently the dimensions of the sheets 15 can be varied, and by adjusting the velocity of rotation of the tool supporting drum 1 so that the time periods elaspsing between successive passages from blade 16 to printing plate 18 and fro printing plate 18 to blade 17 be equal, the printing 19 will be properly centered.

Of course, other applications of the present invention, within the skill of those conversant with the art, may be contemplated without inasmuch departing from the basic principles of the invention.

Claims (9)

1. Method of cyclically treating a continuously travelling web, notably for printing, cutting or pre-forming the edges of boxes or other articles for a continuous web of cardboard by pinpoint contact of tools assembled on a tool supporting die, which comprises the steps of: causing said tools to move at a speed in synchronism with the linear speed of said web, -applying the tools in pinpoint contact against the travelling web, -clearing said tools from the web while preserving the continuity of their movements along a closed-loop path and causing the tool speed to become asynchronous with respect to the web speed.

-applying another treatment cycle.

2. Cyclical treatment method according to Claim 1, wherein said tools are caused to engage said web tangentially.

3. An equipment for the cyclical treatment of a travelling web for carrying out the method of Claim 1, which comprises at least one tool supporting drum extending transversely to the direction of feed of said web, said drum being rotatably driven and adapted to apply a treatment by contact to said web, wherein said tools are assembled on an operative circular sector of said tool supporting drum and means are provided for driving said drum with a circular motion which is synchronous with the passage of said web when said operative sector engages said web, and asynchronous during the remaining sector of the drum rotation.

4. An equipment for the cyclical treatment of a travelling web according to Claim 3, wherein the peripheral surface of said tool supporting drum comprises a plurality of operative circular sectors.

5. The cyclical treatment equipment of Claim 3, wherein several tool supporting drums are disposed seriatim.

6. The cyclical treatment equipment of Claim 3, wherein a counter-cylinder is disposed symmetrically in relation to said web and registers with a corresponding tool supporting drum, the outer cylindrical surface of said counter-cylinder being lined with a resilient lining such as polyurethane.

7. The cyclical treatment equipment of Claim 3, wherein said tools are disposed on an endless belt interconnecting a tool supporting drum and a return cylinder.

8. A method of cyclically treating a continuously travelling web, the method being substantially as hereinbefore described with reference to the accompanying drawings.

9. Cyclical treatment equipment substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.