Wrapping of articles in a tubular wrapping material

Abstract

Method and apparatus for wrapping articles in a tubular casing of plastic or other suitable material. The tubular wrapping material is threaded in pleats over the outer surface of a pipe, whereafter the articles to be wrapped are fed through the hollow interior of the pipe during simultaneously rotation of the pipe. The articles, when leaving the outlet of the pipe, are helically enclosed by the wrapping tube, which thereby is continuously drawn off from the surface of the pipe. The tubular material is then sealed and cut off when the rear ends of the articles have passed the outlet of the pipe.

Parent Case Text

RELATED APPLICATION

This is a continuation-in-part of Ser. No. 205,122 now abandoned, filed Dec. 6, 1971 to which all legal and equitable rights are claimed and whose disclosure is incorporated herein.

Description

BACKGROUND OF INVENTION

The present invention relates to a device and method for wrapping articles in a tubular casing of plastic or other suitable material.

The object of the present invention is to provide a continuously operating method and device having high efficiency and resulting in an attractive protective wrapping, particularly for elongate articles such as rods, fram mouldings and the like.

The method of the present invention is characterized thereby that the tubular wrapping material is threaded over the outer surface of a pipe in pleats, whereafter the articles to be wrapped are fed through the hollow interior of the pipe, during simultaneously rotation of said pipe, and are helically enclosed by said wrapping tube in a continuous process at the outlet of the pipe, after which the tubular material is sealed and cut when the rear ends of the articles have passed the outlet of said pipe.

The feed rate of the articles through the pipe during this process and the speed of rotation of the pipe are preferably adjusted in such way that the tubular wrapping material is brought to enclose the wrapped articles with the desired helical pitch.

In order to perform the method it is suitable to use apparata having a rotatable pipe carrying on its outer surface the tubular wrapping material and being hollow on the inside in order to allow articles to be inserted for wrapping. The outlet end of the pipe is provided with braking and conveyor means in order during the rotation of the pipe to continuously enclose the objects fed through the inside of the pipe, and also with sealing and cutting members near the outlet end of the pipe, as well as feeding members arranged to pull the objects through the pipe.

If very delicate objects are to be wrapped, a non-rotating inner pipe may preferably be arranged in the hollow interior of the rotating pipe.

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

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a preferred wrapping apparatus of the invention;

FIG. 2 shows the apparatus being loaded with wrapping material;

FIG. 3 shows the apparatus in the final stage of the wrapping process;

FIG. 4 shows a front view of the braking and conveyor means arranged at the outlet end of the pipe; and

FIG. 5 shows a side view of the members shown in FIG. 4.

DESCRIPTION OF THE INVENTION

The embodiment of the wrapping apparatus according to the invention shown in FIG. 1 comprises principally a feeding-in station 1, a withdrawal station 2 and a filling station 3. The latter station is intended to prepare the wrapping material for the proposed wrapping process.

The construction and function of the filling station 3 can be seen more clearly in FIG. 2. According to FIG. 2 a plastic tube 4 is wound on to a storage reel 5 which is detachably attached on a rotating plate 6. The plastic tubing 4 is pulled from the storage reel 5 in the direction of the arrow A and is then fed on to a pipe 7 by means of two driving rollers 8, 9, arranged one on each side of the pipe. The bearing casing of the pipe 7 may be vertically sprung and movable on the stand so that it does not need to be dismantled for a charging operation. The driving rollers 8, 9 are suitably covered with a coating of a soft material, for example foam rubber, so as not to damage the plastic tubing 4.

At the end facing away from the storage reel 5, the pipe 7 is provided with an end flange 10. While the plastic tubing 4 is being threaded on to the pipe 7, a guiding mandrel 12 with an opening 11 may be arranged at the end of the pipe, becoming conically narrower in the direction opposite to the storage reel 5, in order to facilitate the process. Between the driving rollers 8, 9 and the plate 6 the plastic tubing 4 may suitably be brought to pass a deflection roller 13. The plastic tubing 4 is thus applied on the pipe 7 in the same manner as sausage skin on the feeding device in a sausage stuffing machine. It has been found that if the pipe 7 has an outer diameter of 5 cm and the plastic tubing 4 used has a diameter of 8 cm and a wall thickness of 0.03 mm, it is possible in accordance with the invention to apply about 100 m of this plastic tubing on each metre in the longitudinal direction of the pipe 7.

When as much plastic tubing as possible has been threaded onto the pipe 7, the so-called "charging" at the station 3 is complete and the pipe 7 is then placed in the machine in the manner indicated in FIG. 1. Rotation or turning of the pipe 7 is achieved by means of a driving belt 31 between a bearing casing 28 and a driving motor 15.

The withdrawal station 2 comprises a pair of rollers 16, 17 driven by a suitable motor and belt transmission, and a sealing and cutting device 19 located between the rollers 16, 17 and the front end 18 of the pipe 7. Before the pipe 7 is placed in the position shown in FIG. 1 in the machine, the control mandrel 12 is removed from the front end of the pipe and instead a stretching, braking and conveyor means 20 is applied and fixed thereto. The conveyor means consists of an annular member retaining a number of spring fingers 21 projecting slightly obliquely and distributed around the circumference of the pipe 7. At their outer ends these fingers 21 have rotatable roller or ball-shaped members 22. An expandable braking ring 29, controlled by an adjustable sleeve 30 is also secured about the annular member. In the immediate vicinity of the conveyor stretching device 20, in the direction of the rollers 16, 17 is a switch contact member 23 in the form of a somewhat inclined tongue, and a heat welding and cutting device 24. This device 24 is in the form of a V-shaped slot and is operated by means of a lever 25.

The apparatus shown in the drawings operates in the following manner.

A number of individual articles 26 or discrete groups of articles, for example fram moldings, which are to be wrapped are inserted in the pipe 7 at the feeding station 1. The articles 26 are then pushed along towards the end 27 of the plastic tubing 4 which is separated from the pipe 7 by means of the fingers 21 and which had been sealed during a previous wrapping operation. The sealing and cutting device 24 is at this stage folded back in its inoperative position. As soon as the front end of the one article 26 passes the contact member 23, the driving mechanism for the rollers 16, 17 and the means 15 for rotating the pipe 7 are started. A predetermined, certain gear ratio between the rotation of the rollers 16, 17 and the rotation of the pipe 7 is provided so that the plastic tube 4 is in principle pulled over and brought to enclose the wrapped articles. When the rear end of the article 26 has passed the contact member 23, the driving of the rollers 16, 17 is disconnected and also the rotation of the pipe 7, the latter preferably with slight delay. The tube 4 is then sealed in the V-shaped heatable welding member 24.

Thus, the stretching and braking mechanism 20 being fixedly connected to the pipe 7 causes the fingers 21 to rotate together with the pipe 7 thereby turning at least that portion of the casing 4 which is stretched tautly about the end of the pipe 7. For this purpose the braking ring 29 is of such a diameter that it serves to provide sufficient friction against the inner surface of the casing retarding its forward movement. The braking ring 29 is preferably formed of elastic material or comprises an expandable link type belt to be radially adjustable by selectively positioning the sleeve 30 axially beneath it to cause the belt to expand or retract. The spring fingers 21 and their rollers 22 function to stretch out the wrapping tube or casing 4 in a radial direction so that in combination with the retarding action of the braking ring 29, the pleats on the pleated casing will be removed and the casing stretched into tight condition well before it is twisted onto the article. The article is fed and moves freely through the tube 7 only in its longitudinal direction and therefore does not impart any twist or countertwist to the casing.

The article to be wrapped is not rotated when the casing 4 is applied thereon but is held securely by the withdrawal rollers 16, 17 which merely pulls the article and the casing in the longitudinal direction (i.e. axially along the axis of the rotating tube). By this combination of the linear operation of rollers 16 and 17 and the simultaneously rotation of the casing 4, jointly with the pipe 7, the casing only is twisted onto the part of the article which is positioned between the pipe 7 and the rollers 16, 17. The rollers 16, 17 exert a pressure against the article and the twisted casing and the twisting tension in the casing exerted by the rotating pipe substantially ceases when the casing and article pass the rollers 16, 17. Thus the casing is rotated relative to the article and is given a helical twist only about the article in the area between the end of the pipe 7 and the rollers 16, 17. The casing is not rotated or wrapped in a conventional spiral overwrap about the entire circumference of the article but is twisted tightly over an otherwise linearly moving object. By twisting the casing onto the article as the article is being moved out of a hollow rotating pipe 7 which carries the pleated casing, all air will be effectively removed from the space between the article and the twisted casing. The casing becomes tightly wrapped about the article, forming a skin which adheres closely to the surface of the article, almost as if it were molded to it. The absence of air within the wrapping and the twisted pattern itself make a wrapping which is much stronger than any obtained previously, even those in which suction was used to remove air from the casing. The desired helical pitch of the wrapping casing is obtained by adjusting the feed rate of the articles through the pipe, the rate at which the articles are withdrawn and the speed of rotation of the pipe 7.

The invention is not limited to the embodiment shown in the drawings, but can be caried in many ways within the scope of the following claims. The device described can easily be modified and adapted to the specific articles to be wrapped, with varying shape. For wrapping particularly delicate articles a stationary inner tube may be provided inside the pipe 7. The withdrawal rollers 16 and 17 may be provided with coatings of varying nature for hard or soft objects to be wrapped. The charging station 3 need not be located on the wrapping machine itself; the tubing 4 can be pushed on to the pipe 7 in a separate unit. The sealing and cutting mechanism shown in the drawings may, of course, be designed in many different conventional ways and can of course be constructed for automatic operation.

Furthermore, the gripping arrangement, i.e., the withdrawal members 16, 17 which pull the articles along the pipe may also be varied in many ways. If desired, the wrapped material can be stretched more effectively by replacing the rollers shown in the drawing with a gripping member which grips the objects when they are fed out of the pipe and then pulls them from the pipe, thus avoiding any slipping of the material and the articles which might occur if they are pulled by a roller system. The bearing casing of the pipe 7 is constructed in such a way that pipes of varying dimensions can be used. In order to seal the wrapping material it is, of course, feasible to use methods other than heat welding; for example a double tape closure with cutting means may be used.

Claims

What is claimed:

1. A method of wrapping articles in tubular wrapping material, comprising the steps of pleating said tubular material onto the outer surface of an elongated pipe, thereafter feeding a stream of articles to be wrapped into said tube through the interior of said pipe toward an outlet end, continuously rotating said pipe during the feeding of the articles while simultaneously stretching said tubular material radially outwardly of the circumference of said pipe adjacent the outlet end to be out of contact with said pipe and to be conjointly rotated therewith, jointly withdrawing said tubular material and said article from the outlet end of said pipe without rotating the same, said tubular material being thereby twisted relative to said article to continuously enclose said article in a helical wrap, and thereafter sealing and cutting said tubular material when the rear end of said article has passed the outlet of said pipe.

2. The method according to claim 1, including the step of adjusting the feed rate of the articles through the pipe and the speed of rotation of the pipe.

3. The method according to claim 2, wherein successive discrete articles are to be wrapped, including the step of interrupting the rotation of the pipe after each article has passed the outlet end of said pipe, said casing being sealed and cut during said interruption.

4. The method according to claim 1, wherein a plastic tube is used as wrapping material and about 100 m of said plastic tube is applied for each metre of said pipe.

5. The method according to claim 1, including the step of initially closing the tubular wrapping material at the outlet end of said pipe.

6. Apparatus for wrapping articles in tubular wrapping material comprising a rotatable pipe adapted to carry on its outer surface said tubular wrapping material and being hollow on the inside to allow articles to be inserted therein for wrapping, means for rotating said pipe, the outlet end of said pipe being provided with means for stretching said tubular material outwardly of the circumference thereof and for simultaneously causing said tubular material to rotate jointly therewith, means for jointly withdrawing the tubular material and articles from the outlet end of said pipe without rotating the same, said tubular material being twisted relative to said article to continuously enclose the article in a helical wrapping, and means located at the end of said pipe for sealing and cutting said tubular material after said article has been wrapped.

7. The apparatus according to claim 6, including a non-rotating inner pipe inserted into the interior of said rotating pipe.

8. The apparatus according to claim 6, wherein said means for withdrawing said article and said tubular material comprises a pair of driving rollers.

9. The apparatus according to claim 6, wherein said rotating pipe is pivotally arranged between a position for feeding the tubular material thereto and a position for performing the wrapping process.

10. The apparatus according to claim 6, wherein said sealing means comprises a substantially V-shaped heat sealing member.

11. The apparatus according to claim 6, wherein said stretching means comprises a plurality of spring fingers projecting slightly obliquely and distributed around the circumference of the pipe, said fingers having at their outer ends rotatable members.

12. The apparatus according to claim 11 wherein said stretching means includes an annular braking member adapted to engage the interior of said tubular material and retard its movement as it is being withdrawn.

13. The apparatus according to claim 12 wherein said braking member is expandable and is provided with means for radially adjusting its diameter.

14. The apparatus according to claim 10, including a contact member located between the outlet end of said pipe and the sealing means, said contact member being arranged, upon contact with the front end of an article, to initiate driving of said withdrawing members and rotation of said pipe and after passage of said article to disconnect the movement of said withdrawing members and the rotation of said pipe.

15. The apparatus according to claim 14 including means for successively feeding a plurality of discrete articles to said pipe and means for controlling the operation of said withdrawal rollers, the rotating pipe, the sealing and cutting means to effect sequential wrapping and separation of each article.