CZ302704B6 - High-speed spindle bearing - Google Patents

Abstract

The present invention relates to a high-speed spindle (1) bearing in a spindle headstock (3) suitable especially for a machine tool. The spindle (1) is provided with bearings (L1) and (L2) the inner races (L1a) and (L2a) of which are strutted by an inner tube (4) while the outer races (L1b) and (L2b) are disposed within a bush (2). Said outer races (L1b) and (L2b) are strutted by an inner shoulder (21) performed in the bush (2) wherein the bush (2) is fixedly mounted in the spindle headstock (3).

Description

High-speed spindle support

Technical field

The invention is a bearing of a high-speed spindle in a headstock suitable especially for a machine tool.

BACKGROUND OF THE INVENTION

The hitherto known high-speed spindle bearings in the machine tool headstock consisted of a conventional bearing in two groups of antifriction bearings. With increasing spindle speed, such a direct spindle bearing in the headstock has ceased to suit. In particular, as the spindle speed increases, the temperature depends on the rolling friction of the rolling bearings. Heat dissipation from the spindle to the headstock is problematic as it is limited by the possibility of rolling bearings, which are also a source of heat. Angular contact ball bearings are used to support machine tool spindles. In the headstock, the outer rings of the roller bearings are scattered through the outer tube housed in the headstock, and the inner rings are scattered through the inner tube. The outer rings of the antifriction bearings are externally defined by the shoulder in the headstock and the headstock of the headstock. The inner bearing rings are braced with the inner pipe. The outer pipe is warmer than the inner pipe and therefore the dilatation of both pipes is different. By warming the bearings, heat is transferred to the outer pipe, which shifts the thermal dilatation of the outer bearing rings in the spindle. Differential displacement of the inner and outer rings increases the pressure on the ball bearings, resulting in an additional heat source.

For this reason, the outer span tube was cooled, which for a larger dimension appeared suitable for heat dissipation. For this purpose, the outer tube at the outer diameter adjacent to the inner diameter of the headstock was provided with channels in a screw-rod. At one end, cooling oil was fed into the channel and drained at the other end. Cooling reduces heat expansion and reduces the pressure on the bearing balls. A disadvantage of this arrangement is that even if the outer tube is shortened, the bias between the bearings is reduced only after axial displacement of the outer rings due to the force distribution on the bearing ball. The problem arises when the clearance between the outer rings of the bearing and the headstock is exhausted before the outer ring moves due to internal forces in the bearing. In this case, the outer ring becomes stuck in the headstock and does not move. The internal forces in the bearing continue to increase and with them the temperature, which can result in the destruction of the bearings. Such an arrangement by its design did not allow a long-term increase in spindle speed.

SUMMARY OF THE INVENTION

The bearing according to the invention of the high-speed spindle in the headstock is particularly suitable for a machine tool, for example a horizontal boring machine. The spindle is equipped with angular contact bearings, the inner rings of which are spaced by a pipe and the outer rings are housed in a housing. The outer rings are braced by the inner shoulder formed in the housing in which they are received.

The housing is fixed in the headstock. Such a bearing precisely defines the relative position of the two bearings and ensures better heat transfer between the spindle and the headstock. As the temperature rises, the sleeve lengthens, and thus the outer bearing rings are displaced relative to the inner rings. As the temperature decreases as the sleeve moves back, the outer rings of the bearings, which are housed in the outer span, are simultaneously displaced while simultaneously releasing the pressure of the two rings on the bearing balls.

When the housing on the outer surface is provided with cooling channels that connect the inlet and outlet of coolant formed in the spindle. Both the housing is cooled and the bearings are cooled. Also, the cooling ducts may be formed in the spindle on an inner diameter adjacent to the outer diameter of the housing. The backward displacement force is therefore not due to decomposition

But by shortening the outer pipe caused by its cooling. The coolant, which is generally oil, dissipates heat both from the housing and partly from the outer rings of the bearings and contributes both to limiting the thermal expansion of the outer housing and to maintaining their optimum operating temperature of up to about 60 ° C. At optimum operation it is possible to control the preload in the bearings, which increases the accuracy and reliability of the bearing. Such an arrangement also makes it possible to reduce the mounting clearances which have so far been designed to compensate for thermal expansion.

Description of drawing in drawing II)

The attached drawing shows the longitudinal section of the fastening spindle of the invention.

and? Description of an exemplary embodiment

The mounting of the high-speed spindle even in the headstock 3 is particularly suitable for a machine tool, for example a horizontal boring machine. The spindle 1 is provided with bearings L1 and L2, the inner rings L1a and L2a of which are supported by the inner tube 4. The outer rings Lib and L2b are housed in the housing 2 and are

The inner rings L1a and L2a are held on one side by the face 11 and on the other side by a sleeve 6 together with a thrust device 5 mounted on the spindle i. Lubricant rings 7 are incorporated into the bushings 2. Lubricant feeds for bearings L1 and L2 to the lubrication rings 7 are not shown for simplicity. The housing 2 is fixed in the headstock 3. The housing 2 is provided on the outer surface with cooling channels K connecting the inlet P and the coolant outlet O formed in the spindle LV of this embodiment are three sets of channels K and three of the respective inlets P and outlets O. can be combined in a suitable way to control the temperature of the housing 2.

iii During operation of the spindle as well as in the headstock 3, together with increasing speed and operating time, the temperature of the individual parts gradually increases, unevenly. The temperature of the sleeve 2 gradually exceeds the temperature of the inner pipe 4. The flow of oil through the inlets P and the outlets O maintains the temperature of the sleeve 2 at the desired level, thereby ensuring optimum overvoltage of the bearings L1 and L2 and thereby their reliable operation.

Claims (3)

PATENT CLAIMS Placing a high-speed spindle (1) in a headstock (3) particularly suitable for a machine tool whose spindle (1) is provided with bearings (L1) and (L2), whose inner rings (L1a) and (L2a) are punctured by an inner tube ( 4), characterized in that the outer rings (L1b) and (L2b) are housed in the housing (2), wherein the outer rings (L1b) and (L2b) are braced by the inner shoulder 45 (21) formed in the housing (2), the housing (2) being fixedly mounted in the headstock (3). High-speed spindle bearing according to claim 1, characterized in that the housing (2) is provided on the outer surface with cooling channels (K) which connect the inlet (P) and the outlet (0) of the coolant formed in the headstock (3). High-speed spindle bearing according to claim 1, characterized in that the headstock (3) is provided on the inner surface adjacent to the housing (2) with cooling channels (K) connecting the inlet (P) and outlet (O) of the coolant formed in the coolant. headstock (3).