FABRIC MADE FROM EXTRUDED, CUT TO SIZE HOLLOW TUBES BACKGROUND OF THE INVENTION
Field of the Invention
The present invention concerns a link belt, especially for paper machines, with hinge wires extending in the cross machine direction and link elements extending in the machine direction. Each link encloses at least two adjacent hinge wires .
Description of the Prior Art A papermaker's link belt fabric has been disclosed in
U.S. Patent No. 4,469,221. It has a number of circular hinge wires running in the cross machine direction bound together via link elements. A number of differently shaped link elements are shown. Each link element has passage openings at its ends for accepting neighboring hinge wires. The passage openings are slit to permit them to be expanded and snapped around the hinge wires .
In such a link belt, there is a possibility of expansion of the slit passage openings and, also, only a limited stability in the direction of tensioning. Additionally, the link elements are prone to breaking at the expandable sections bordering the passage openings. Another disadvantage of such a link belt is that air permeability can not be adjusted significantly. Since link belts are generally used in the dryer section of a paper machine, air permeability is an important property and therefore is preferably adjustable.
So-called wire link belts are described in U.S. Patent Nos. 4,395,308 and 5,364,692. Such wire link belts also have
a number of hinge wires extending in the cross direction. The hinge wires may be circular, flat, oval, or rectangular in cross section or a variation thereof. In wire link belts, the hinge wires join together wire spirals, each of which surrounds two neighboring hinge wires. Generally, each wire spiral intermeshes with its neighboring wire spirals.
In some applications, filler elements may be incorporated between each pair of hinge wires in the area surrounded by the wire spirals to reduce the air permeability as disclosed in U.S. Patent No. 5,364,692. Permeability may also be reduced by providing spirals having upper or lower surfaces which are wider than the ends thereof, as disclosed in U.S. Patent No. 4,528,236, which is incorporated herein by reference.
However, the manufacture of wire link belts is not simple. Generally, the wire spirals are produced via plastic deformation under the influence of heat. This is an expensive, tedious and time consuming process. In addition, left- and right-spiraled wire spirals have to be kept on hand to be joined and intermeshed with each other in a proper sequence. A further disadvantage is that damage to a single wire spiral can result in a break of the entire wire link belt.
Therefore, there exists a need for a link belt that it is resistant to tension, can be adjusted for air permeability, and can be easily produced.
SUMMARY OF THE INVENTION
The present invention generally provides a paper machine belt comprising hinge wires extending in the cross machine direction and a plurality of ring link elements extending in the machine direction. Each ring link element opens in the cross machine direction and encloses at least two of the hinge wires.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an isometric view of a link belt made in accordance with the present invention.
Figure 2 is a side elevation of the link belt of Figure 1.
Figure 3- is a top plan view of the link belt of Figure 1. Figure 4 is a top plan view of an alternate embodiment of the link belt.
Figure 5 is a side elevation of the link belt of Figure 4.
Figure 6 is a top plan view of a ^second alternate embodiment of the link belt.
Figure 7 is a side elevation of the link belt of Figure 6.
Figure 8 is a top plan view of a third alternate embodiment of the link belt . Figure 9 is an isometric view of a preferred tube and ring elements formed therefrom.
Figure 10 is an isometric view of an alternate embodiment of a ring link element.
Figure 11 is a side elevation of the ring link element of Figure 10. Figure 12 is a partial isometric view of a link belt forming apparatus .
Figures 13a-19a are side elevation views of the forming apparatus of Figure 12 during formation of a link belt.
Figures 13b-19b are front elevation views of the forming apparatus of Figure 12 during forming of a link belt.
Figures 13c-19c are top views of the forming apparatus of Figure 12 during formation of a link belt.
Figures 20-27 are top views of an alternate forming apparatus during forming of a link belt .
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments will be described with reference to drawing figures where the numerals represent like elements throughout.
As shown in Figures 1-8, the link belt 1 has a number of hinge wires 2 extending in the cross machine direction. The hinge wires 2 can have various cross sections, such as the hinge wires presently used in spiral link belts. They are preferably equally spaced with respect to each other.
Each pair of neighboring hinge wires 2 is jointly surrounded by a ring element 3 having a single opening 4. Preferably, the ring elements 3 are adapted to the shape of the hinge wires 2 in that the ring openings 4 correspond to
the geometry of the hinge wires 2. It is preferable that the hinge wires 2 and ring openings 4 be rounded along their lateral edges regardless of their cross section as part of the hinging function. In the preferred embodiment, the ring elements 3 have a substantially quadratic cross section and run straight on the top and bottom side. In this way, flat surfaces are formed. It is also possible to provide convex or concave surfaces in order to attain better adaptation to specific conditions. The ring elements 3 may have a variety of configurations, such as those currently utilized in spiral link belts. The configuration shown in Figure 8 is similar to that disclosed in U.S. Patent No. 4,528,236. In this configuration, the top and bottom surfaces of each ring 3 are wider than the ends thereof.
Referring to Figure 1, two neighboring ring elements 3 are arranged around hinge wire 2 and offset with respect to each other in the machine direction. For example, ring element 3b encloses two specific hinge wires 2b and 2c. Neighboring ring element 3a surrounds only one of the two above-mentioned hinge wires 2b as well as the next hinge wire 2a in the machine direction. Ring element 3c encloses the other of the two above-mentioned hinge wires 2c as well as the hinge wire 2d neighboring on the other side. This pattern is continuous so that two neighboring hinge wires 2 are jointly surrounded by only every other ring element 3 viewed in the cross direction of the link belt 1. It is also possible for the ring elements 3 to enclose three or more successive hinge
wires 2, the spacing of the hinge wires 2 being held constant in such an embodiment through appropriate staggering of the ring elements 3. This is shown in Figures 6 and 7.
When the belt 1 is assembled, channel 6 extends in the cross direction between neighboring hinge wires 2 over the entire width of the link belt 1. Filler elements, such as are found in U.S. Patent No. 5,364,692, can be placed in these channels 6. In this way, the air permeability of the link belt 1 can be adjusted to a desired value. If desired, a woven or non-woven batt layer can be affixed to one or both sides of the belt in a known manner, such as is disclosed in U.S. 4,528,236.
The ring elements 3 and the hinges 2 can be formed from any number of materials, including but not limited to plastics, metals, or any combination thereof. The materials may be treated or reinforced by additives such as fiberglass. As shown in Figure 9, the ring elements 3 are preferably sections of a desired width, that are formed from a continuous hollow tube 10 of the desired cross section. In the preferred embodiment, tube 10 is an extrusion and the ring elements 3 are formed in a cutting apparatus. Alternatively, the ring elements 3 may be injection molded.
An alternate ring element 103 is shown in Figures 10-11. In this embodiment, the machine side of the ring element 103 has a separation 105. The ring element 103 may be formed with this configuration or may be formed flat and then bent to the desired configuration. These ring elements 103 may be used to form an entire belt, but are preferably used only as
replacement elements for fabric elements which are broken or damaged since they will not be required to provide as much MD stability in such an application.
A first method of manufacturing the belt 1 is shown in Figures 12-19. The forming apparatus 20 extends in the cross direction and comprises a ring discharger 22, a forming platform 24 and an advancing arm 26. The ring discharger 22 is supplied with ring elements 3. Preferably, the number of stacks of ring elements 3 is equal to half the number of ring elements 3 in the machine cross direction of the desired belt. The stacks are spaced in the cross machine direction by a distance equal to the width of a ring element 3.
Assembly of the belt 1 is shown in Figures 13-19, wherein each figure represents a progression in the formation process. As shown in Figures 13a-13c, when the ring discharger 22 is in a first alignment, the even row ring elements 28 drop to the forming platform 24. Next, as shown in Figures 14a-14c, advancing arm 26 preferably advances the even row ring elements 28 in the machine direction by one half of a ring element. Simultaneously, the ring discharger 22 moves in the cross machine direction by the width of a ring element to its second alignment. When the advancing arm 26 is removed, as shown in Figures 15a and 15c, the odd row ring elements 27 fall to the forming platform 24, as shown in Figure 15a. A forming wire 2 is placed through the channel by the aligned positions of ring elements 27 and 28, as shown in Figures 16a and 16c. The advancing arm 26 advances the belt 1 in the machine direction while the ring discharger 22 simultaneously
moves back to its first alignment, as shown in Figure 17. When the advancing arm 26 is withdrawn as shown in Figures 18a and 18c, the next group of even row ring elements 28 falls to the forming platform. A pintle wire 2 is inserted through the channel formed by the advanced ring elements 27 and the newly positioned ring elements 28, as shown in Figures 19a and 19c. This process is repeated to form a belt 1 of a desired length. An alternate method of forming the link belt 1 is shown in Figures 20-27. The forming apparatus 40 extends in the cross machine direction and comprises a forming jig 42 and advancing pins 44. As shown in Figure 20, hollow tubes 10 are inserted into the jig 42. Individual ring elements 3 are formed across the desired width of the forming apparatus 40. Odd rows of the ring elements 27 are then advanced in the machine direction by the advancing pins 44, as shown in Figure 22. Hinge wires 2 are inserted in the channels formed between the advanced odd row ring elements 27 and the non-advanced even row ring elements 28, as can be seen in Figure 23. The assembled portion of the belt 1 is advanced beyond the jig 42 and hollow tubes 10 are again inserted into the cutting jig 42 , as shown in Figure 24. The advancing pins 44 advance the even row ring elements 28 in the machine direction to align with the last of the previously advanced odd row ring elements 27, as can be seen in Figure 25. Hinge wires 2 are then inserted into the newly formed channels. As can be seen in Figure 27, a hinge wire 2 joins the advanced portion of the belt 1 with the newly advanced ring elements 28. The
assembled belt is advanced as the process continues to form a belt 1 of a desired length.