The present invention relates to an arrangement for applying a band of coating material to a selected portion of the shank of headed articles, such as, for example, bolts, rivets and other fasteners.
A basic system for applying such a coating is described in U.S. Pat. No. 3,795,224 to Robert E. Batson et al. As pointed out in this patent, in applying a band of material to the shanks of such articles, it is desirable to be able to maintain the quantity of material which is applied and to control the area of the shank over which the material is applied. In providing for such control of the size and quality of the band of coating material, it is necessary that the articles be fed in a predetermined orientation along a conveying path past a coating applicator with a predetermined distance between each of the articles.
The orientation of such articles must initially be set prior to the time at which the articles enter the conveying path. Additionally, it is necessary that the spacing between the articles be set prior to the time that the articles travel past the coating applicator. In order to provide for such a spacing between the articles, the system in the above-noted patent provides a conventional escapement mechanism positioned along the conveyor path. In the operation of this system, a stream of articles is initially fed onto the conveyor path with the appropriate orientation. The articles are subsequently engaged by the escapement mechanism which delays the continued passage of the articles and releases them with a set spacing between each article.
The articles are then conveyed past the coating applicator, where a selected quantity of material is applied to the shanks of the articles. After the material is applied, the coating applicator includes a smoothing block for smoothing the material out into the desired continuous band. This band of material, which is applied, helps to form a tight interlocking arrangement when the article is inserted into a corresponding threaded member. The coating material, which would be provided in applying such a band, is generally of a viscous or paste-like consistency and thus when applied covers in the threads of the shank of the article. In applying the coating material however it is necessary to maintain several of the bottom threads of the shank of the article free of the coating material so that these threads are free to initially engage the corresponding member for joining the article and the member together.
In carrying out such a coating process, it, therefore, becomes necessary to maintain a synchronized flow of the articles past the coating station with the articles rotating and moving in a forward direction past the coating device. As each article moves past the coating device, only a selected quantity of material is emitted from the coating device and this emission occurs in synchronization with the movement of the article.
The utilization of such a conveyor system, as descirbed in the above-noted patent, together with a track feeding system leads to several problems. At the junction of the track and the conveyor path, the articles have a tendency to easily jam thereby interrupting the process. There is also a tendency of the articles to pile up along the conveyor path in the area between the junction with the track feed and the escapement mechanism. Since the conveyor elements are flexible members, when the articles pile up there is a tendency for conveyor members to bulge thereby causing the articles to drop out of the path. Furthermore, with the utilization of a conventional escapement mechanism, the conveyor members have to grip the articles within the escapement area to permit emptying and, consequently, the escapement function itself tends to fight the grip of the conveyor members.