DE2630740B2 - Grinding spindle unit - Google Patents

Description

45

The invention relates to a grinding spindle unit for very high spindle speeds on grinding machines Rolling bearings arranged free of play, in particular angular contact bearings, on the spindle ends, axially and radially are supported in a spindle housing, the radial support of the roller bearing at one end of the spindle is formed by at least three hydrostatic bearing pockets distributed around the circumference of the bearing.

In known spindle units for grinding machines (DE-PS 9 29 698 and DE-PS 6 72 359) it is from Disadvantage that only certain limit speeds can be reached with roller bearings. As with grinding machines A high rigidity of the spindle units is required, the roller bearings are partially under Built-in preload As a result of the lack of adjustment options, constraining forces arise in the rolling bearing that Heat the bearing strongly and limit its maximum speed, as misalignment and elasticity Deformations that occur when processing a *> 5 Workpiece occur, not be compensated. Another disadvantage is the vibration sensitivity the spindle unit. After all, it is very difficult to obtain the necessary rigidity values for grinding machines, the vibration behavior and the damping properties of the spindle unit to match men that an optimal running behavior is achieved.

From DE-AS 19 65 302 is a device of the type listed above for Supporting a roller bearing in a housing is known to compensate for the temperature-related Change of the game at least three radially directed throttle points for the introduction of the under pressure standing pressure medium are provided between the pressure ring and the housing. Such a spindle unit is also limited in its speed, as there is no setting option and the Stiffness, vibration behavior and damping properties for optimal running behavior not possible

Furthermore, hydrostatic spindle units for grinding machines have become known (roller bearing technology - Reports from FAG KUGELFISCHER GEORG SCHAEFER & CO - 1970-3, p. 69, or HAURI, "Hydrostatic bearings on machine tools", CH magazine "Technische Rundschau", No. 46 of Nov. 10, 1972, pages 5 and 7), which some of the Avoid the aforementioned disadvantages. Spindle units mounted in this way are characterized by high Rigidity and good damping, but the disadvantage here is the high speed that occurs at high speeds Friction loss of hydrostatic bearings compared to roller bearings. The hydrostatic bearings namely only have low friction at low speeds. With increasing speed, the increases Overcoming friction about quadratically and requires at speeds with which grinding machines be operated, a very high energy requirement of the drive machines and a complex oil recooling. Extensive devices must also be installed so that in the event of a failure of the Hydraulic pumps prevent the high-speed bearings from seizing (see e.g. DE-Gbm 73 04 945).

It is therefore the object of the invention to provide a spindle unit for grinding machines, which in particular allows a significantly higher limit speed, is operationally reliable and also with different machine types shows optimal running behavior.

The solution to this problem can be seen from the characterizing part of claim 1.

Further advantageous refinements can be found in claims 2 to 5 below.

The all-round floating support of the roller bearings enables a significantly higher limit number. Included a lot of drive energy is saved, as the rolling bearings have a much lower speed at high speeds Have friction than high-speed sliding bearings. But also in the event of a sudden failure of the pressure oil supply the bearings would not seize up like conventional hydrostatic spindle bearings, but could, even if no longer under optimal conditions, continue to run.

Via the throttles, the hydrostatic bearings surrounding the rolling bearings can be adjusted with variable Pressure can be applied. In this way, the radial and axial preload of the roller bearings can also be achieved control, which makes it possible to adjust the running behavior of the spindle unit to different cutting conditions and to optimally adapt speeds. The spindle unit can now also be used in different machine types built in, as they are no longer on the special

The vibration behavior of a machine type must be coordinated. This advantage reduces the variety of types and facilitates storage. An annular piston chamber enables the same preload to be maintained despite different thermal expansion. The damping can be adjusted by changing the toughness affect the spindle unit. About the pressure and the amount of lubricant and Coolant, the running behavior of the bearing is further optimized.

In that the hydrostatic radial bearings are in a plane with the intersections of the pressure angle line of the Angular contact bearings are located on the bearing axis, no additional moments are introduced into them.

The invention will be explained in more detail in the following figure, in which an inventive Grinding spindle unit is shown in section.

The spindle 1 is in two angular contact ball bearings 2 and 3 via an intermediate sleeve 4 and 5 in the housing 6 stored. In the housing 6 spaces are provided which, together with the intermediate sleeves 4 and 5, are hydrostatic Bearings 7,9,10 and 12, the piston chamber 10 and Pressure chambers 8 and 11 for the lubricant supply channels form. The pressure medium is supplied via adjustable throttles 7 ', 8', 9 ', 10', 11 'and 12', which are from the outside and can be set independently of each other. Depending on the level of the set pocket pressure and the viscosity of the Pressure oil results in a very specific rigidity and damping of the bearing. The axial preload force that is exerted by the pressure in the annular piston chamber 10 or in the hydrostatic axial bearing 9 and the The stiffness of the rolling bearings is determined and can be regulated via the adjusting throttles 9 'and 10' and the corresponding To be adapted to the circumstances.

1 sheet of drawings

Claims (5)

Patent claims: 1. Grinding spindle unit for very high spindle speeds on grinding machines with backlash-free arrangement Rolling bearings, in particular angular contact bearings, on the spindle ends are axially and radially in one Spindle housing are supported, the radial support of the roller bearing at one end of the spindle is formed by at least three hydrostatic bearing pockets distributed around the circumference of the bearing, thereby characterized in that the axial support of the two roller bearings (2; 3) on the spindle housing (6) each consists of at least one hydrostatic bearing (9 or 10) and that the radial support of the roller bearing (2 or ι s 3) at the other end of the spindle by at least three hydrostatic bearing pockets distributed around the circumference of the bearing (7 or 12) is formed. 2. Grinding spindle unit according to claim 1, characterized in that the hydrostatic bearings (7; 9; 10; 12) between the spindle housing (6) and an intermediate sleeve each surrounding the roller bearing outer rings (4; 5) are arranged. 3. Grinding spindle unit according to claim 1, characterized in that for cooling the rolling bearings (2; 3) these via pressure medium channels with pressure spaces provided in the area of the hydrostatic bearings (8; 11) are connected, the pressure in the pressure chambers (8; 11) through upstream throttles (8 '; 11') is adjustable 4. grinding spindle unit according to claim 1, characterized in that the bearing center of the hydrostatic bearings (7; 12) for radial support in a radial plane with the points of intersection of the The pressure angle line of the angular contact bearings (2; 3) is located on the bearing axis. 5. Grinding spindle unit according to claim 1, characterized in that, as known per se, the Pressure medium supply of the hydrostatic bearings (7; 9; 10; 12) from the outside and independently of one another ίο takes place and can be controlled via adjustable throttles (7; 9; 10; 12).