Cable drum - has one-piece core in three sections, hinging together on axes parallel to its own

(54) NAME Mountable cable drum and method for its manufacture (56) PUBLICATIONS QUOTED:

AU B 62746/86 (B65H 75/14), US A 4 471 919 (242: 115) (57) SUMMARY:

A plastic cable drum has two end plates (1) with protruding brackets (3) for the tubular core (2) of the cable drum. The core (2) has a longitudinal joint (8) with the snaps (11) and is made in one piece with three sections, which are joined via articulators whose axles are parallel to the longitudinal axis of the core. The middle section is considerably narrower than the other two sections.

The cable drum is produced by injection molding of the end plates (1) and the core (2). In this way, the core is prepared in an opened, folded state. The narrow center section of the core (2) is centered on a support and the end plates (1) are placed on the center section

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The numbers in brackets indicate international identification code, INID code. Letters in clamps indicate international document code.

469 836 i

TECHNICAL FIELD

The present invention relates to a cable drum comprising two end plates having their projecting sides projecting by means of which the tubular core of the drum is attached, the core having at least one longitudinal joint with snap means and the core being formed in a three-section piece, which are connected to each other via articulated devices whose articulated axes are substantially parallel to the longitudinal axis of the core.

The invention also relates to a method for producing such a cable drum, wherein two end plates and a tubular core are produced as separate parts by injection molding, the end plates being provided with projecting attachments on their opposite sides and the core being produced in an open, folded state by being provided with a longitudinal joint with snap members and two joints whose axes are substantially parallel to the longitudinal axis of the core.

OLDER TECHNOLOGY

A cable drum of the type mentioned earlier is known. This cable drum is made by injection molding of plastic and has separately manufactured end pieces and a core consisting of two approximately semi-cylindrical, separate shells which can be joined by means of snap fasteners. In assembled condition, the core is arranged around the end plate fasteners.

Furthermore, US 4 471 919 discloses a cable drum with separate end plates and a core with a longitudinal joint with snap fasteners for the core end. The core is divided into two approximately half-cylindrical sections via a longitudinal joint.

Although a longitudinal joint in the core according to this public publication is eliminated, the strength is not sufficient.

A cable drum of these older types has a very limited * strength, so great thicknesses of goods are required if the cable drum is to be used. Furthermore, the snap brackets have an insufficient locking effect, which is why an empty drum can split if dropped. Finally, the mounting is problematic because engagement must be established between several different parts at several different places simultaneously.

PROBLEM

The object of the present invention is to provide a cable drum which eliminates the above-mentioned problems in previously known cable drums. It is thus an object of the invention to provide a cable drum which can be manufactured simply and rationally by injection molding of plastic and which can be mounted in a very smooth and convenient manner. It is also an object of the invention to provide a cable drum which provides good strength even at relatively small thicknesses of material in the plastic material used.

Finally, the invention also has for its object to provide a method which allows rational production of the cable drum.

PROBLEM SOLVING

The object of the invention is achieved with respect to the cable drum itself if it is characterized in that the side sections of the core have at their opposite ends projecting inwardly projecting pins which can be received in corresponding holes in the fasteners, with the side surfaces of the pins being approximately parallel to such a diameter. which is perpendicular to a diameter through the center section of the core, thereby obtaining a snap action that holds the end plates and the core together.

In a preferred embodiment, according to the invention

469 836 also conveniently states that the middle section of the core has a considerably smaller extent in the circumferential direction of the core than the other two sections.

With regard to the method, the object of the invention is achieved if the method is characterized in that the center section of the core located between the joints is centered on a support, that the end plates are placed on the middle section and are held in the correct positions, after which the side sections of the core are pivoted around the joints and interconnected d endplates.

COMPOSITION OF DRAWING FIGURES

The invention will now be described in more detail with reference to the accompanying drawings. On these shows:

Fig. 1 the cable drum according to the invention in a so-called exploded view; Fig. 2 the core of the cable drum seen from the inside and wide and opened and Fig. 3 the core of the cable drum seen in the same condition as in Fig. 2, but along the axis direction of the core.

From Fig. 1 it can be seen that the cable drum according to the invention comprises two end plates 1 and a core 2. On their opposite faces, ie the inside sides, the end plates have brackets 3 which serve to secure the core 2 so that it is mounted and supported on the brackets in mounted condition. 3rd

Furthermore, from Fig. 1 it can be seen that the fasteners 3 have a circumferential groove 4, the edge of which lies closest to the end plate 1, so that the bottom of the groove is narrower than its mouth. The opposite edge may be perpendicular to the center axis of the cable drum but may also be inclined in the opposite direction to that of the nearest end plate located. Because the groove 4 in this way is narrower at its bottom is obtained with one

469 836 correspondingly to the end portions of the core 2 a good clamping and position fixing of the core when it is brought around the bracket 3 and to extend down into the inwardly tapered groove 4 with a molded projection 7.

On the side 4 of the groove 4 facing away from the end plate 1 itself, the bracket 3 has a substantially cylindrical support member 5 which abuts a corresponding smooth surface internally of the core 2.

Although not shown in Fig. 1, the end plates 1 have central openings through which a shaft or spindle may extend when the complete cable drum is used.

The shape of the end plates 1 can, of course, vary and in one embodiment it may be a circular disk, while in another embodiment it may be a polygon, preferably regular and with a relatively large number of corners.

The core 2 is roughly in the form of a circular cylindrical tube which at its opposite ends 6 has the radially inwardly projecting strip 7, whose cross-sectional shape corresponds to the cross-sectional shape of the groove 4. This strip not shown in Figure 1 (see, however, Figure 2, reference numeral 7 ) is occupied and positioned in the groove 4 in the mounted state of the cable drum.

Figure 1 further shows that the core 2 has a longitudinal joint 8 which lies in a diameter plane through the longitudinal center axis of the cable drum. The joint 8 is held together in that the edge portions 9 and 10 of the core that meet in the joint are provided with snap fasteners 19 which engage in corresponding openings 11. In Fig. 1, the core 2 is shown in the closed position, ie the position it has when it is in position. mounted on the brackets 3.

In Figures 2 and 3, the core 2 is shown in a widespread, open state, approximately in its position during manufacture in an injection molding tool. From these figures it can be seen that the core is sectioned and has two side sections 12, 13 and a middle section 14. These three sections are made in a

469 836 continuous piece and are joined via two guide devices 15 and 16 consisting of a foil thin (thickness in the range 0.40.8 mm) band of the plastic material from which the three sections are made. These, the different sections joining band-shaped portions are at the outer peripheral surface of the core at the bottom of V-shaped grooves 17 and 18 as shown in Fig. 3.

In Figures 2 and 3, the center section is shown with a width or a cross-sectional dimension in the plane of the drawing which is approximately 2045% of the width of the two side sections 12 and 13. However, a width of about 30% is preferred.

For closure of the core so that it has a generally cylindrical tubular shape, the snaps provided at the opposite edges 9 and 10 are used. In the embodiment shown in Fig. 3, these snaps are snap arms 19 which have hook-shaped lugs at the free outer ends. These snap arms snap with the hook-shaped projections into the openings 11 shown in the opposite edge 10 of the core of Fig. 1.

In order to strengthen the connection along the joint 8, the opposite edge 10 of the core has support lugs 20 which lie internally against the inside of the second edge portion 9 so that the edge portions are guided in a radial direction relative to each other. The support lugs 20 and the snap arms 19 are distributed along the length of the joint 8 so that preferably one or two support lugs 20 are located between adjacent snap arms 19.

To further strengthen the joint along the joint 8, the edge portion 9 with the snap arms 19 may also have support lugs 20 (however not shown in the drawing).

It should be mentioned parenthetically that in Fig. 2 both the snap arms 19, the support lugs 20 and the openings for these intended are omitted.

To improve the connection of the core 2 and the brackets 3

469 836 preferably has the two side sections 12 and 13 reinforcing lugs 21 which are located on the circumferential strips 7 and which extend radially inwardly therefrom. These non-reinforcing lugs are intended for receiving into corresponding openings 25 at the bottom of the circumferential grooves 4 (see FIG.

1).

The reinforcing lugs 21 may be four to the number on each side section but may also be two or six, possibly several. Regardless of the number and also the location of the reinforcing lugs, these side surfaces 22 which, in the mounted state of the core, are substantially parallel to a diameter of the core which is in turn perpendicular to another diameter of the core extending through the center section 14. Also, the design of the boundary surfaces of the apertures intended for receiving the reinforcing lugs has the corresponding shape and alignment.

To further improve the joining between the core 2 and the end boards 1, the strip 7 on the center section 14 has longitudinally directed lugs 24. The lugs 24 may conveniently have the same radial extension as the surrounding portions of the strips 7 and are accommodable in correspondingly widened portions of the grooves 4 in the brackets 3.

It can be seen from Fig. 2 that the center section 14 has two openings 23.

These openings are intended for receiving control pins arranged in a mounting tool used in mounting the cable drum. Thus, this mounting tool has a support surface which can be substantially complementary to the outside of the center section 14 of the core 2 and which has pins that fit in the openings 23 for position fixing of the center section. The support surface is preferably slightly shorter than the core 2 itself, so that its end portions extend outside the support surface. Further, the mounting device includes brackets for the end plates 1 so that they can be placed with the brackets 3 on the center section 14 and with the lugs 24 of the center section in the corresponding widened portions of the grooves 4. In this position, the brackets 3 rest on the center section

469 836 and the end pieces are held in the correct position, partly by the engagement of the lugs 24 in the recesses and partly by means suitable for the mounting device. For final mounting of the cable drum, then only the two side sections 12 and 13 of the core are pivoted towards each other so that their end portions are caused to surround the brackets 3 and the strips 7 to extend into the grooves 4 so that in the final phase the snap arms 19 are engaged in the corresponding recesses. in the edge portion 10. This oscillation of the two side sections 12 and 13 is conveniently effected by force mechanisms located in the mounting device. Furthermore, the mounting device contains suitable means to ensure that the center section 14 and the resting brackets 3 with the end plates 1 are not lifted when the swing of the side sections 12 and 13 is in progress.

The alignment described above of the projections 21, and in particular their side surfaces 22 and the position shown in the drawings, means that the side surfaces 22 will form a certain angle towards the direction of movement at the very moment when they are to enter their openings in the bottoms of the grooves 4. Thereby, a certain elastic deformation occurs in the material upon insertion of the projections 21, thereby also obtaining a snap action which holds together the end plates and the core. However, the main purpose is to prevent such relative movements between the end plates and the core which could occur if a mounted cable drum is dropped against a support with the joint 8 substantially straight up or straight down and which could open the snaps 11 and 19.

The invention can be modified within the scope of the following claims.

469 836