Patent Application
20200139611
The invention relates to a guide mandrel used for machine insertion of plastic or rubber tubes into a shaping mold, the guide mandrel comprising a rigid rear portion and a flexible front end portion.
The invention also relates to a device for machine insertion of plastic or rubber tubes into a shaping mold with a guide mandrel which comprises a longitudinal frame, adapted to be fastened to an end element of a 3D manipulator, and means for inserting the tube into a labyrinth.
For the bending of plastic or rubber tubes, molds comprising a molding labyrinth (hereinafter referred to as “labyrinth”) made of a durable material into which a straight tube is pressed to be shaped. After passing through the furnace/steam molding process and after cooling, the tube maintains the spatial shape of the labyrinth into which it was inserted at the beginning of the process. During the insertion of the straight tube into the spatially shaped labyrinth, the initially straight tube is subjected to bending or twisting or other stresses. So as to avoid undesirable deformations of the tube cross-section when inserting the straight plastic or rubber tube into the labyrinth, such as slumps or depressions in the tube wall in the bends, or other unwanted deformations, a reinforcing elastic body is inserted into the tube cavity along the entire length of the tube (e.g., a spring which with its outer surface supports the inner wall of the tube pressed into the labyrinth), the elastic body being bent according to the shape of the labyrinth along with the shaped tube pressed into the labyrinth. After the shaping process of the tube and the stabilization of the form of the shaped tube, the inner elastic body of the shaped tube is pulled out, which requires considerable strength and also creates a risk of damage or deformation of the tube already formed. Another disadvantage, particularly in thin-walled tubes, is the risk of deformation of the surface of the shaped tube exactly according to the surface of the elastic body, e.g. a spring. Another disadvantage is that for each shaped tube, one elastic body is required throughout the shaping of the tube, which also involves high financial, logistic and storage requirements of the process with the inserted elastic bodies. Last but not least, the step of inserting the elastic body into the tube and removing it from the tube is a phase in the process which should be omitted to shorten the working cycle (tact time).
The aim of the invention is to eliminate or at least reduce the disadvantages of the background art.
Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
The aim of the invention is achieved by a guide mandrel for machine insertion of plastic or rubber tubes into a shaping mold, whose principle consists in that the flexible front end portion is formed by an elastic front end portion, and whereby the guide mandrel is adapted to be mounted at its rear end in a device for automatic insertion of plastic or rubber tubes into the shaping mold.
The principle of the device for automatic insertion of straight plastic or rubber tubes into the mold is that on a frame is mounted at its rear end the guide mandrel of the shaped tube, which is adapted to put on the tube, whereby the guide mandrel is provided with an elastic front end portion adapted to maintain the presence of the mandrel in the tube at the bending point and to minimize the ovality of the bent tube. The elastic front end portion of the guide mandrel is associated with an inserting pulley mounted on the frame, wherein at least one pair of guide pulleys are mounted on the frame along the sides of the guide mandrel in the area between the inserting pulley and the rear end of the guide mandrel.
An advantage of the present invention is to enable high-quality machine insertion of plastic or rubber tubes even into spatially complex 3D shaping molds—labyrinths, effectively preventing undue deformation of the tube cross-section, such as a slump or depression of the tube walls in the bends or other undesirable deformations, thereby eliminating the need to leave the inner mandrel in the tube throughout the molding process, as well as the need to remove the inner mandrel after shaping the tube and also eliminating the risk of damaging the shaped tube when removing the inner mandrel. The step of inserting an elastic body into each tube prior to insertion into the mold and removing the elastic body from each tube has been left out by the present invention and a further reduction in the working cycle is achieved. In thin-walled tubes, the risk of deformation of the shaped tube is virtually eliminated, precisely copying the surface of the inserted elastic body during the shaping process, i.e. during heating and subsequent cooling with the relaxation of internal stresses.
The invention is schematically represented in the drawings, where:
Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.
The invention will be described with reference to exemplary embodiments of a guide mandrel for machine insertion of plastic or rubber tubes into a shaping mold and an exemplary embodiment of a device for automatic insertion of straight plastic or rubber tubes into the shaping mold—the labyrinth.
The device for automatic insertion of straight plastic or rubber tubes into the shaping mold—the labyrinth—comprises a longitudinal frame 1 which is adapted to be fastened to the end element of a 3D manipulator (not shown). In the illustrated embodiment, the frame 1 for fastening to the end element of the 3D manipulator (not shown) has a clamping projection 10 on the upper side of the front portion of the frame 1. In an unillustrated exemplary embodiment, the clamping projection 10 is provided on a different part of the frame 1, or is formed by another suitable method.
On the lower side of the frame 1, a guide mandrel (pin) 6 of the shaped tube 3 is mounted at its rear end 61. The guide mandrel 6 is located in the direction of the frame 1 length towards the front end 11 of the frame 1, where the guide mandrel 6 is provided with an elastic front end portion 60 adapted to maintain the presence of the mandrel 6 in the tube 3 at the bending point and to minimize the ovality of the bent tube 3, or minimizing slumps or depressions of the tube material 3 in the bending region.
On the frame 1, ideally at its front end 11, is rotatably mounted an inserting pulley 2, which serves to press the shaped plastic or rubber tube 3 into the labyrinth 4, which is in
At least one pair of guide pulleys 5 are further mounted on the frame 1 along the sides of the guide mandrel 6 in the area between the inserting pulley 2 and the rear end 61 of the guide mandrel 6. The guide mandrel 6, as viewed from the front, passes through the space defined by the inserting pulley 2 and the guide pulleys 5, which increases the stability of the attachment of the guide mandrel 6 at its rear end to the frame 1, in fact the stability of overhung (free-end) mounting of the guide mandrel 6 on the frame 1, which allows to guide the shaped tube 3 placed on the guide mandrel 6, as will be described in more detail hereinafter.
In the illustrated embodiment, at least one auxiliary support 7 of the mandrel 6 and of the tube 3 is situated in the area between the guide pulleys 5 and the rear end 61 of the guide mandrel 6 mounted on the frame 1. The auxiliary support 7 is particularly suited to large lengths of the mandrel 6 and the tube 3. In an unillustrated exemplary embodiment, the device is implemented without the auxiliary support 7.
As shown in
In the embodiment of
In an unillustrated embodiment, which is a modification of the embodiment of
The insertion of the tube 3 into the labyrinth 4 starts with putting the entire tube 3 on the guide mandrel 6, ideally as far as to its rear end 61. Ideally, the length of the mandrel 6 corresponds to the length of the inserted tube 3. Subsequently, the device approaches the front end of the labyrinth 4 and the front end of the tube 3 is clamped in the clamping device at the front end of the labyrinth 4. Afterwards, the 3D device is moved in a controlled manner by the inserting pulley 2 along the labyrinth and the tube 3 is gradually pressed into the 3D shaping labyrinth 4 by the inserting pulley 2. Simultaneously, the tube 3 is bent according to the shape of the labyrinth 4 and at the same time this bending of the tube is supported from the inside of the tube 3 by the elastic front end portion 60 of the guide mandrel 6, which is along its length from the inserting pulley 2 towards the front end of the mandrel 6 bent as required and according to 3D shape of the labyrinth 4. At the same time, the tube 3 gradually “slips” off the mandrel 6 as the insertion into the labyrinth 4 proceeds, while the elastic front end portion 60 of the guide mandrel 6 moves along with the inserting pulley 2 towards the end of the labyrinth 4 until the whole length of the tube 3 is inserted into the labyrinth 4.
The solution can be used especially for machine insertion of plastic or rubber tubes into shaping molds, such as labyrinths and similar 3D shaping tools.
Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18204564.1 | Nov 2018 | EP | regional |
