Bandsaw blade with straight teeth and set teeth

Abstract: A bandsaw blade for sawing of metal, comprises straight teeth (13,14) and set teeth (11,12). The set teeth (13,14) have equal height and occur in pairs with the same equal distance (15) between the teeth in each pair. The distance (16,18) from any set tooth to an adjacent straight tooth has values which are different and larger than the distance between the set teeth. The bandsaw blade may have from one to three straight teeth (13,14) between each two pairs of set teeth, and at least a leading straight tooth (13) being higher than the set teeth. Moreover, at least a leading straight tooth (13) may have chamfers on both sides.

Description: Background Bandsaw blades for cutting of metal have long been made with differences in height, pitch distance and setting between the teeth, which has proven to be an efficient way to avoid vibrations and to get smoother cut surfaces especially when cutting large diameter solid sections. One known way to make such a saw blade is to arrange the teeth in recurring groups with variable pitch distances between the teeth, the length of this group should preferably be at least as great as the thickness of the material to be cut. It has also been shown that to achieve best results it is important to have very good repeatability of the setting, not only the amount and angle of setting, but also the angle of twist the of the tooth during setting. One known way to do this is to use tools large enough for punching, grinding and setting the whole group of teeth at a time, but for long groups that requires expensive tooling. Setting the teeth individually is difficult to do with precision, since the twist and the spring-back after setting are much influenced by the distance to and setting of the adjoining teeth, which may vary within the recurring group. FR-1.406.673 discloses a bandsaw blade according to the preamble of claim 1. The present invention concerns a bandsaw blade with teeth arranged for easy precision setting and limited tooling size, even for saw blades with large teeth and long average pitch distance. Description A bandsaw blade according to the invention is described with reference to the figure 1 which shows part of a saw blade. According to the invention, all set teeth are arranged in pairs, one set to the right and one set to the left, with equal and relatively short distance between the teeth in the pair. Other straight teeth are arranged between the pairs and separated from the pairs by distances which are longer than the distance within the pair, in order to reduce the influence on the setting. To produce the effect of a long recurring group, the distances between straight teeth or from straight teeth to the set pair may be varied, randomly or according to a predetermined rule. As shown in figure 1, the saw blade is provided with set teeth, half of them (11,21) set to the right and half of them (12,22) set to the left. The set teeth occur in pairs of each one set to the right and one set to the left, and the distance (15) between the teeth of each pair of set teeth is equal. This allows simultaneous setting of both set teeth of the pair with one set of hammers and anvils after aligning the tools by indexing on the first tooth (11,21) of the pair. The setting tools will then also be aligned with the second tooth (12,22) of the pair since their distance (15) is constant and equal. Preferably, the setting direction order left-right or right-left between the teeth of each pair should be the same, since that allows a more even distribution of cutting depth for the set teeth. Between the pairs of set teeth are provided one, two or three straight teeth (13,14,23,24), which should be higher than the set teeth to ensure a smooth cut even at the beginning since the first chips of each cut are then produced without any lateral forces. Preferably, there should be a leading highest straight tooth (13,23) with large chamfers followed by a slightly lower straight tooth (14,24) with smaller chamfers or no chamfers. Since the influence of adjoining teeth upon the setting decreases sharply with the distance, the straight teeth should be located at a distance (16,18,26) from the nearest set teeth exceeding the distance (15) between the set teeth of each pair. The distance (17,27) between the straight teeth does not influence the setting precision but should leave enough gullet area for the chips. To achieve the best vibration reduction corresponding to long recurring tooth groups, the distances (16,18,26) between set and straight teeth should be varied, which can be done by making the punching or grinding tools produce flat-bottomed gullets which may overlap to some extent, which may be varied according to a predetermined scheme, or randomly. The chamfers on leading straight teeth are ground with indexing on those teeth, and is not influenced or disturbed by distances to other teeth.

Claims: Bandsaw blade for sawing of metal, comprising straight teeth (13,14) and set teeth (11,12), the set teeth having equal height and occurring in pairs with the same equal distance (15) between the teeth in each pair, characterized by the distance (16,18) from any set tooth to an adjacent straight tooth having values which are different and larger than the distance between the set teeth. Bandsaw blade according to claim 1, characterized by having from one to three straight teeth (13,14) between each two pairs of set teeth. Bandsaw blade according to claim 2, characterized by at least a leading straight tooth (13) being higher than the set teeth. Bandsaw blade according to claim 3, characterized by at least a leading straight tooth (13) having chamfers on both sides.

Inventors: HELLBERGH HAKAN, HELLBERGH, HAKAN
Applicants: KAPMAN AB
Application year: 1999
Main classification: B23D61
IPC codes: B23D61