Link belt for use in furnaces

A link belt for use in a sintering furnace, which is made of a plurality of first links, each of said links having working surfaces for supporting objects to be carried on the belt. A plurality of rollers are positioned intermediate certain of said first links, and a plurality of pins pass through apertures within said first links and within said rollers.

Not Applicable.

PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable.

REFERENCE TO A SEQUENCE LISTING

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a link belt for use in a continuous furnace and, more particularly, link belts having roller configurations.

2. Background Art

It is known to advantageously treat various articles by subjecting the articles to high temperatures for preselected periods of time. Such treatment may, for example, effect sintering of articles which are made by compacting powdered refractory metals or ceramics. In this regard, some of these processes include method steps where the articles are transported through a heat treating zone in a furnace, rather than being loaded and unloaded in batches.

For example, it is known to transport articles through heating zones on link belts made of wire which are formed by conventional belt links. Somewhat similar to a wire belt is a transport belt disclosed in Miller, Jr. et al., U.S. Pat. No. 3,535,946 issued Nov. 15, 1995. The Miller, Jr. et al. patent discloses a belt made up of a succession of interwoven links, with each of the links formed of a length of tungsten wire which has been treated to a temperature of at least 400° C. The links are wound around an elliptical mandrel so as to provide, when cooled, a link which is in the form of a slightly flattened helix. Miller, Jr. et al. further disclose that they believe that by the avoidance of sharp bends in the link form and by the provision of a large number of interlocking contact points between links, strength and failure resistance are improved.

Autenrieth, et al. U.S. Pat. No. 5,199,868 issued Apr. 6, 1993 discloses a continuous furnace which serves for the simultaneous two-sided sintering of sintered sheets upon substrates. The furnace of Autenrieth, et al. includes a muffle and a conveyor belt longitudinally traversing the muffle and carrying the substrates. The belt consists of a pair of individual belts which are guided in parallel next to each other in a synchronous manner. The belt surfaces are mutually inclined at a small angle to the horizontal in the muffle. The substrates are self supporting between two parallel lateral edges. The substrates lie with one lateral edge on the belt surface of one belt and with the second lateral edge on the belt surface of the other belt. In this manner, the bottom side of each substrate does not touch the individual belts.

Fritsch, U.S. Pat. No. 2,994,917 issued Jul. 28, 1954 discloses an apparatus for converting metal powder into wrought metal shapes comprising at least one pair of oppositely disposed and laterally spaced vertical compactor elements. Each of the compactor elements includes an endless link belt mounted to travel about a pair of support wheels. The adjacent outer surfaces of the link belt form substantially continuous pressure surfaces inclined at an acute angle to the common axis of the pair of compactor elements. The adjacent pressure surfaces define a truncated V-shaped passageway. Means are provided for moving the link belt at the same rate of speed and in opposite directions so that the adjacent pressure surfaces travel uniformly toward the narrow end of the passageway defined by the compactor elements. In this manner, loose metal powder is compacted into a precompressed strip having sufficient mechanical strength to retain its form. This strip is introduced into a pair of pressure rolls. A power feed hopper is adapted to introduce loose metal powder into the wide end of the passageway. A pair of oppositely disposed pressure rolls having the axis of the rolls disposed in a horizontal plane define a roll gap with a width which is less than the width of the narrow end of the passageway.

Daringer, U.S. Pat. No. 5,558,204 issued Sep. 24, 1996 describes a weld-free belt assembly in which elongated length modules are coupled in widthwise and side-by-side relationships by transversely-oriented coupling modules. An internal cavity is defined within each link along with a surface configuration on each side of the link. This configuration defines an entry access portion for a coupler and slot portions for enabling relative longitudinal movement of the coupler, while retaining the coupler within the internal cavity. The interfitting coactions of the links and couplers enable an assembled belt to move from linear planar travel into a curved path so as to establish an endless belt configuration. Relative movement of the couplers within a link cavity enables longitudinal collection of links along the inner circumference when the belt enters a curvilinear travel path in approximately the same plane, and enables re-extension for return to linear travel. An assembled belt can be driven longitudinally by sprockets. Also, the belt can be driven along a serpentine path by lateral-edge dynamic frictional drive. Alternatively, a similarly driven and layered helical-path “carousel” arrangement can be used. Special configuration lateral-edge links provide protrusion-free lateral edge surfaces enabling smooth dynamic frictional drive along inner circumference surfaces during curvilinear travel.

DETAILED DESCRIPTION OF THE INVENTION

The principles of the invention will now be described, with respect to a sintering furnace10and a link belt14as illustrated inFIGS. 1-20. Advantageously and in accordance with various aspects of the invention, the link belt overcomes relatively high friction due to its roller configuration. In addition, as a result of the link belt in accordance with the invention having a relatively flat upper surface142(comprising lateral surface144and longitudinal surfaces146) and offset rollers128, larger parts are allowed to be placed on the belt. Still further, the offset rollers allow for use in current furnaces which use friction drives. The belt uses rollers128which can be formed of ceramic material. The use of the ceramic precludes spot welding of the rollers128to the pins132. Still further, the use of ceramic material for the rollers avoids the potential for “stiction” if the belt is stopped while under relatively high temperatures. The belt links can be constructed of iron-nickel super alloys or other suitable metal. This type of construction will maintain relatively high strength, while also maintaining relatively better ductility than a fully ceramic belt. The belt has a relatively lower initial cost of ownership than belts which consist of wire mesh systems, or which otherwise consist of fully ceramic systems.

Turning toFIG. 1, the drawing illustrates a sintering furnace system10. The furnace system10includes a sintering furnace12. It should be emphasized that link belts in accordance with the invention may be utilized with apparatus other than sintering furnaces. For background information, sintering consists of a method for making objects from powder, by heating the material (heating below its melting point for solid state sintering) until the particles adhere to each other. Sintering is traditionally used for manufacture of ceramic objects, and also has uses in fields such as metallurgy.

For providing the sintering functions associated with the furnace12, a link belt14is utilized to transport the items to be sintered through the relatively high temperature furnace12. The link belt14can take on any of a number of different configurations, and will move through the furnace12in the direction shown by the arrows16. The link belt14itself moves along a path determined by a series of system rollers18. The drive mechanism for the link belt14is provided by a conventional motor drive20which exerts forces on the link belt14between the motor drive20itself and the drive system roller22. As further shown inFIG. 1, items (not shown) which are to be subjected to the sintering process through the furnace12can be placed on the link belt14at the charge end24. Once the sintering process is completed through the furnace12, the items which have been sintered can be removed at the discharge end26of the link belt14.

The link belt14will now be described with respect toFIGS. 2-20. As shown inFIG. 2, the link belt14can include a series of belt sections102. The belt sections102can be linked together in a manner which will be apparent from the subsequent description herein. With reference toFIGS. 2,3,4and6-13, each of the belt sections102can include a series of alloy center links104, such as shown in the drawings. In the particular belt section102shown inFIG. 2, there are 8 center links104illustrated. With reference toFIG. 6, each of the center links104can include a horizontally disposed bottom section106. Integral with the horizontal section106are a pair of opposing end sections or noses108. As shown inFIGS. 8-13, the noses108include a first end section110and a second end section112. Each of the noses108can include a downwardly directed arcuate section114. InFIG. 6, the first end section110includes an arcuate section114which curves inwardly toward the horizontal section106. Correspondingly, the second end section112also includes a downwardly directed arcuate section114which curves inwardly toward the horizontal section106. In this manner, the end sections108oppose each other.

As each of the arcuate sections depend downwardly, the sections form straight sections140. The straight sections140terminate in what can be characterized as working surfaces142. The working surfaces142act as the actual contact surfaces. These working surfaces142are particularly shown inFIGS. 3,4and7. As particularly shown inFIG. 7, the working surfaces142include a pair of laterally extending surfaces144. Integral with the lateral working surfaces144is a longitudinally extending working surface146.

In addition to the foregoing, and as particularly shown inFIGS. 9 and 13, the arcuate sections114and straight sections140, along with the bottom section106, form a pair of pin holes148. The pin holes148comprise apertures116which are utilized to receive pins as described in subsequent paragraphs herein. In addition to the pin holes148, each of the center links144also include a center post150. The center post150is utilized to provide rigidity and strength to the entirety of the center link104. With this particular configuration of the center link104in accordance with the invention, the link104is made relatively light weight by the structure of the link and portions of the structure which essentially comprise hollow interior. Advantageously, and in accordance with certain aspects of the invention, the links104may be constructed of iron-nickel super alloys. Such construction will maintain relatively high strength, while also maintaining and facilitating better ductility then may be obtained from a fully ceramic belt. Also, it should be noted that a crown may now exist on the top plates. This avoids any requirement of a corrugated plate, while still using a friction drive.

In addition to the alloy center links104, the belt section102also includes a series of alloy side links120. In the particular illustration of the belt section102shown inFIG. 2, there are two alloy side links120. However, it should be emphasized that additional side links120would exist on the side of the belt section102opposing the side on which the side links120are shown. The side links120will now be described with respect toFIGS. 14-20. With reference thereto, each of the alloy side links120includes a vertically disposed central section122. At opposing ends of the central section122are a pair of end sections124. Each of the end sections124has a arcuate-shaped end surface. Formed horizontally through each of the end sections124is an aperture126. The alloy side links120are utilized to secure together the alloy center links104, and the apertures are utilized with alloy pins as described in subsequent paragraphs herein to secure the alloy center links and rollers together on a “widthwise” basis. Each of the alloy side links120can also be constructed of iron-nickel super alloys, for maintaining strength and ductility.

Turning again toFIGS. 2-4, each belt section102also includes a series of rollers128. Advantageously, and in accordance with certain aspects of the invention, the belt section102essentially is formed of a flat upper surface (through the surfaces142,144,146of the alloy center links104) and the rollers128are “offset” relative to the belt center links of the section. Such offset rollers128can be utilized with current furnaces having friction drives. As shown primarily inFIG. 4, each of the rollers128is of a cylindrical configuration and includes an aperture130(FIG. 2) extending horizontally therethrough.

The rollers128may be formed of various materials. However, advantageously and in accordance with certain aspects of the invention, the rollers128may be formed of ceramic materials. Ceramic material has a relatively high thermal conductivity. These materials are used in a number of different types of applications where it is necessary to withstand relatively extreme temperatures. For example, ceramic is often used in disc brakes. In this regard, the use of ceramic for the rollers128will tend to avoid spot welding of the rollers128to the alloy pins. Further, the rollers128will also avoid the potential for “stiction,” if the belt14for some reason has stopped while under temperature.

In addition to the aforedescribed elements, the belt section102also includes a series of alloy pins132. The alloy pins132are particularly shown inFIG. 4and are of a cylindrical configuration. As shown primarily inFIGS. 2,3and4, the pins132are utilized to secure together the rollers128, alloy side links120and alloy center links104. Where the pins extend through to the side links120, pin connectors134can be utilized to secure the pins in an appropriate manner. As also shown inFIGS. 2,3and4, the alloy pins132will extend through the apertures130,126and116.

In accordance with the foregoing, the belt section102can be formed. It should be emphasized that the width of the belt section102can be adjusted as desired by adding or subtracting the individual elements of the belt sections102.

It will be apparent to those skilled in the pertinent arts that other embodiments of link belts in accordance with the invention may be designed. That is, the principles of the invention are not limited to the specific embodiments described herein. Accordingly, it will be apparent to those skilled in the art that modifications and other variations of the above-described illustrative embodiments of the invention may be effected without departing from the spirit and scope of the novel concepts of the invention.