The present invention relates to a saw axle for floatingly supporting a plurality of saw blades, which are caused to rotate with the axle by virtue of a form-locking effect achieved between the outer contour of the axle and corre¬ sponding holes in respective saw blades. The invention also relates to a saw blade for use with such an axle.

Circular saws that are used to saw logs and blocks into smaller dimensions include a plurality of axle-mounted saw blades. The saw blades are usually fitted floatingly on the axle, i.e. are loosely displaceable thereon, therewith simplifying relative positional changes between the blades for adaptation to different blade settings, among other things. Each blade is guided by outer blade guides which coact with said blade and which can be moved between differ¬ ent blade positions along the axle.

The blades are dogged by the rotating axle through the medium of splines, the axle being provided with a plurality of radially outwardly projecting splines which extend axially along the axle, wherein the blades are provided with corre¬ sponding recesses for coaction with the axle-mounted splines; see US-A-3, 516, 460, for instance.

One drawback with the use of splines is that the blades are liable to wear grooves in the splines at those regions where the blades are in contact therewith. This can cause problems when wishing to move floatingly-mounted blades through a very short distance to a new blade setting, since the grooves tend to return the blades to their old setting and therewith make it difficult to finely adjust the blade settings.

Furthermore, when a plurality of splines are used the attachment is not statically determined, since it is not

known whether or not the blade has contact with all splines when a sawing operation is started.

A conventional splined axle is relatively expensive to renovate, since it is necessary to remove the entire axle and possibly send the axle to a workshop to be reground, which is an expensive exercise.

One object of the present invention is to provide an axle on which saw blades can be floatingly-mounted and which provides statically determined contact with respective saw blades.

Another object is to provide such an axle which can be manufactured at relatively low cost, which is easy to grind and whose surfaces can be readily treated, and which can be renovated in a cost-effective manner when so required.

Still another object of the invention is to provide a saw blade that can be mounted on an inventive axle.

In accordance with the invention, the first object is achieved with a saw axle of the kind defined in the introduc¬ tion which is characterized in that both the outer contour of the axle and the contour of the blade-mounting hole present three main sides for achieving statically determined three-point contact between axle and blade.

As a result of this three-point contact, the blades will be self-centred relative to their rotational axes while being easily adjusted to desired positions in the longitudinal direction of the axle. A three-sided axle constructed with the invention is relatively easy to produce and treat.

The three sides of the axle are suitably arcuate in shape, e.g. circular-arcuate, with the centres of respective arcs lying at the corners of an equilateral triangle.

According to one preferred embodiment, the three arcuate sides merge together via arcuate parts whose radius of curvature is smaller than the radius of curvature of the main sides. Despite having three sides, an axle of this construc- tion will have high mechanical strength while requiring the provision of only relatively s all holes in the saw blade, meaning that the available useful saw radius of the blade will be relatively large.

In a particularly preferred embodiment, the axle comprises a core axle and a sleeve non-rotatably mounted thereon, wherein the outer contour of said sleeve presents said three main surfaces for coaction with corresponding main surfaces of respective blade-mounting holes.

When renovating an axle of this construction, all that is needed is to remove the sleeve from the axle and to send the sleeve to a workshop for re-grinding, if necessary.

The core axle and the inner surface of the sleeve are preferably circular in shape, wherein the sleeve is held firmly to the axle with the aid of at least one clamping joint. The sleeve may be provided with passageways through which oil under pressure can be delivered to a space between the core axle and the sleeve for separating the same in an axial direction.

This thus facilitates fitting of the sleeve to the axle and its removal therefrom, therewith also facilitating renovation of the sleeve, among other things.

Other features of an inventive saw axle and an inventive saw blade will be apparent from the following Claims.

The invention will now be described in more detail with reference to an exemplifying embodiment thereof and also with reference to the accompanying drawings, in which

Fig. 1 is a partially sectioned view of one embodiment of an inventive axle comprised of a core axle and a surrounding sleeve;

Fig. 2 is an end view of the axle shown in Fig. 1, as seen in the direction of the arrows II-II; and

Fig. 3 illustrates an inventive saw blade which can be fitted to the axle shown in Figs. 1 and 2.

Fig. 1 illustrates a core axle 1 having a conically tapering end-part or trunnion 2 which is intended to be supported in a bearing, not shown. The inner end 3 of the axle is rotat- ably mounted in a saw frame (not shown) and driven in a desired, conventional manner. The core axle is surrounded by an outer axle sleeve 4 provided with a through-penetrating bore for accommodating the core axle 1. The bore has a circular cross-section of different diameters over different parts in accordance with the different parts of the core axle 1, which also has a circular cross-sectional shape.

As will be seen from Fig. 2, the outer contour of the sleeve 4 comprises three main sides which in the case of the illustrated embodiment are comprised of circular-arcuate surfaces whose centres are located at the corners of an equilateral triangle located inwardly of the arcs. The arcuate main sides merge with one another via circular- arcuate parts of smaller radius of curvature, the centres of said parts also lying at the corners of the equilateral triangle.

One of the advantages afforded is that as a result of the outer configuration of the sleeve, the stress concentrations therein will be low and the fatigue strength of the sleeve commensurately high. The use of such an outer profile for a saw axle on which inventive saw blades 17 having a centre hole 18 adapted to the profile of the sleeve (see Fig. 3) are

floatingly-mounted provides significant advantages. As the axle and the mounting holes in the saw blades have three main sides, the positions of the blades will always be statically determined as a result of said three-point contact. The saw blades are thus self-centering around the rotational axis. The arcuate abutment surfaces of the axle and the blade- mounting hole respectively also results in successive contact over a longer distance than that achieved with conventional splines. This results in a larger abutment and force-trans- mission surface and therewith less risk of grooves being worn in the outer surface of the sleeve 4 among other things, such grooves otherwise making it difficult to finely adjust the settings of the blades, as mentioned above.

An axle according to the Fig. 1 embodiment also provides the advantage that in the event of any damage, it is only necessary to draw the sleeve 4 from the axle 1 and send the sleeve to a workshop for renovation. The sleeve 4 is secured to the core axle 1 to this end with the aid of a clamping joint 5, which may be of any convenient, known kind. In the illustrated case, the clamping joint includes two conical, flanged sleeves 6, 7 which are displaced relative to one another with the aid of tightening screws 8 which function to tighten the sleeve 4 on the axle 1. The reference numeral 9 identifies a spacing ring which functions to prevent undesirable movement between the various elements.

The sleeve 4 includes parts 10, 11 which have a centering function in coaction with the core axle 1, wherein a certain amount of clearance exists between the sleeve and the axle along the part 12 intermediate of said centering parts 10, 11. The space provided by this clearance is connected to oil inlet and oil outlet passageways 13 and 14 respectively, wherein oil is also delivered through said space to a circumferentially extending groove 15 via a passageway 16 provided in the inner surface of the sleeve 4.

When wishing to remove the sleeve from the core axle 4, e.g. for renovating purposes, a pressure oil source is connected to the passageway 13 and air is allowed to pass out through the passageway 14 at the same time. The pressure exerted by the oil will cause the sleeve 4 to be pushed from the core axle 1 to the right in Fig. 1. ^" The sleeve 4 can thus be removed easily from the axle 1 with the axle left mounted in the machine. Only the journal bearing coacting with the trunnion 2 need be swung to one side. When the sleeve has been renovated, the sleeve can be readily refitted to the axle 1 and clamped firmly thereto with the aid of the clamping joint 5. The invention thus simplifies renovation of the axle and substantially reduces the costs entailed thereby.

An axle that is constructed in accordance with the aforegoing is easier to manufacture than conventional splined axles. Scratches and the like can also be ground or polished away and surface coatings applied more easily than in the case of conventional splined axles, due to the smooth and even surfaces of the inventive axle. The use of a three-sided axle having rounded or cut corners provides the advantages of static determined contact with the holes in the saw blades while retaining the largest possible "useful" blade radius to enable logs and blocks of large dimensions to be sawn. A purely triangular shape would greatly reduce the maximum sawing measurement.

The invention has been described in the aforegoing with reference to a preferred embodiment thereof where the axle comprises a core axle and a sleeve surrounding the axle. It lies within the purview of the invention, however, to provide a solid saw axle with the aforedescribed outer contour so as to obtain the desired three-point contact and to dispense with the use of a surrounding sleeve.

It will be understood that the sides of the three-sided axle/sleeve may have a curvature other than a purely circular curvature, as may also the transitions between the main sides of the axle/sleeve. The use of rounded transitions between said sides, however, is _t - advantageous from the aspect of stress concentrations in comparison with abrupt transitions, although such transitions are nevertheless conceivable. It will also be understood that when a sleeve is used, the manner in which the sleeve is held firmly on the core axle and the forms of the coacting parts may be varied as desired without departing from the scope of the inventive concept. The blade toothing may also be varied in accordance with the use for which the blade is intended.