The invention concerns a spindle drive for a veneer lathe.

For said purpose, usually an electric motor is used which transfers the rotating power to the spindles by the intermediate of a reduction gear and a chain transmission. It is also common practice that there is only one power source per lathe, fitted at the proximity of one end of the lathe. The rotating power is transferred to the other spindle through a transmission shaft, a chain drive and/or a set of cogwheels.

It is a direct consequence of the construction used that the construction is massive, both in respect of the static components and in respect of the revolving components. Also, the construction is strictly bound to the operational dimensions that have been chosen, adaptation to different log lengths being possible only within the scope of the ordinary axial movement of the spindles, i.e. the spindle stroke.

However, in practice, the nominal dimensions of the logs to be turned vary starting from a log length of 950 mm, whereas a usual upper limit of a log length is 2750 mm. Log lengths higher than 3000 mm also occur. ithin the scope of the spindle stroke, the lathe can, however, be adapted within considerably narrower limits, whereby, in the dimensioning of the lathe, the nominal dimension of the log to be turned must be taken into account. Said circumstance can be considered to be quite a restrictive factor.

The primary object of the present invention is to simplify the rotation drive equipment of the spindles and to make them such that they require less maintenance, respond to

operation commands more rapidly (smaller mobile masses), and are less noisy in operation. At the same time, the construction of the whole lathe becomes simpler, and possibilities are obtained for the use of modular con¬ structions.

In this way, possibilities are also obtained for adaptation of the veneer lathe to a larger variation in the log length than what is possible within the scope of the grasping stroke of the spindles, i.e. the so-called spindle stroke.

Further, displacement of the spindles in a plane perpen¬ dicular to the spindle axis is permitted, which provides the possibility to provide the lathe with several opera¬ tional applications, such as, for example, the possibility to operate with two different knife settings.

The main object can be achieved in accordance with the invention by means of a lathe which comprises spindles or spindle pairs directed one opposite the other and receiving power of rotation at each end of the lathe, which said spindles or spindle pairs can be displaced within the scope of the spindle stroke axially in opposite directions in relation to one another so as to grasp the log to be turned, according to the primary characteristic of the invention, so that the spindles or spindle pairs are provided with drive motors of their own at each end of the lathe to produce the power of rotation.

The other characteristics of the invention come out from the accompanying patent claims.

The invention will be described with the aid of the accompanying drawing illustration, wherein the log rotating spindles and their drives are shown in a reduced way.

In the embodiment shown, the spindles consist, in the conventional way, of two spindle pairs 1,2 and l',2', each pair comprising spindles of different diameters which can be displaced in relation to one another tele- scopically in the way known in prior art. Each of the spindles is mounted on an end frame 6,6' of its own. In the embodiment shown, the electric motors that operate the spindles are mounted so that the rotor of the motor is mounted directly on the spindle shaft 4,4', and the stator is mounted on the end frame 6,6'. Thus, in said embodiment, the spindles, the drive motor and the end frame can be formed as a whole unit.

In the simplest embodiment, such a unit can be mounted in a lathe on guides parallel to the spindle axes to operate jointly with an opposite, stationary spindle arrangement, which may be provided with a traditional drive. Such a construction permits ready adaptation of the lathe to different log lengths. A more natural construction can, however, be produced if each of said spindle arrangements is composed of said whole units, each of which is mounted on the lathe as displaceable in the direction of the spindle axes.

Further, two opposite units may be mounted in the lathe construction as also displaceable in planes perpendicular to the spindle axes. By means of this arrangement, e.g., operation of the lathe with two knife settings is per¬ mitted. In such a case, the knife settings may be placed, e.g., at different levels, in which case a certain knife setting is intended for peeling the veneer in a certain direction of rotation of the log, whereas the other knife setting is intended for peeling the veneer in the opposite direction of rotation of the log. Thus, by means of the lathe, it is possible to feed two veneer treatment equip¬ ments, and, moreover, the veneers peeled for said equip¬ ments may have different widths compared with one another.

As the drive motor, advantageously a squirrel-cage motor constructed for said purpose is used. For peeling of veneer, the motor must be provided with regulation of the speed of rotation, which can be accomplished by means of regulation of frequency in the case of a squirrel-cage motor. The maximum speed of rotation of the motor may be about 600 rpm. The construction described above can also be used in the rounding-turning that precedes the peeling of the veneer, in which case the motor may have a constant speed of rotation, e.g. 300 or 375 rpm.

In the peeling of veneer, for each spindle unit a motor is needed whose power is about 90 to 120 kW. Said power requires efficient cooling of the motor, which can be accomplished, e.g., as oil cooling. These details, which are obvious for a person skilled in the art, are not illustrated in the accompanying drawing.

Another possibility to accomplish the invention is to make use of hydraulic drive. In such a case, the hydraulic motor is mounted advantageously, in accordance with the electric drive illustrated in the figure, on the spindles of the lathe. As a motor, in particular a radial-piston motor can be concerned, whose cam ring is mounted on the shaft of the spindle, in the way corresponding to the rotor of the electric motor. On the other hand, the cylinder group of the motor is mounted on the end frame. The pump unit which produces the operating pressure can be accomplished as a unit common of both motors even though separate pump units for each motor are not excluded from the embodiments of the invention.

Differing from the embodiments described above, the basic idea of the invention may also be accomplished by means of a more traditional technique of drive gear, i.e. by providing the spindles at each end of the lathe with

drive motors of their own, from which the power of rotation is passed to the spindles by means of a gearbox and a chain transmission. In such a construction, if the spindle unit at one end of the lathe is constructed as a unit that com¬ prises the spindles, the drive and the end frame and that is displaceable on guides parallel to the spindle shafts, the lathe can be easily adapted to varying log lengths.

By means of the construction of said sort, several advan¬ tages of the embodiment illustrated in the drawing, which were referred to above, can, however, not be obtained.