Bearing device

Abstract

The invention relates to a bearing device (1) for a rotationally driven and axially at least temporarily loaded shaft (3), comprising a bearing housing (2) through which the shaft is guided, wherein at least two seals (4a, 4b) which are spaced apart from one another in the axial direction are provided between the shaft and the bearing housing, wherein a pressure chamber (5) which is filled with a pressure fluid, in particular oil, is provided in the region between the seals between the shaft and the bearing housing. According to the invention, the seals are designed as high-pressure sealing rings in such a way that the pressure fluid in the pressure chamber is at a pressure of at least 10 bar or can be maintained at said pressure.

Description

[0001] 77793-WO-KMT / Wl-Wl 04.07.2025

[0002] Description

[0003] Storage device

[0004] The invention relates to a bearing device for a rotary-driven shaft that is axially loaded, at least temporarily, comprising a bearing housing through which the shaft passes, wherein at least two axially spaced seals are provided between the shaft and the bearing housing, and wherein a pressure chamber filled with a pressure fluid, in particular oil, is provided in the area between the seals between the shaft and the bearing housing. A preferred application area of ​​the invention is injection molding machines, and in particular the rotary and linear-driven screw of the plasticizing unit.

[0005] In screw plasticizing units, large axial forces act on the screw shaft during each injection molding cycle. This is particularly true during the injection molding phase, when material in the screw pre-chamber is transferred from the cylinder of the screw plasticizing unit into an injection mold by a linear movement of the screw. High pressures typically occur in the screw pre-chamber, and the axial forces acting on the screw shaft are correspondingly large. For this reason, appropriately sized rolling bearings, suitable for the axial forces generated, are usually used between the screw shaft and the bearing housing. Such rolling bearings are comparatively expensive and require a large amount of space.

[0006] Based on this, the invention aims to provide a bearing device specifically suited for the screw shaft of a screw plasticizing unit, characterized by a compact design and comparatively low cost. 77793-WO-KMT / Wl-Wl 04.07.2025

[0007] This problem is solved by a storage device according to claim 1. Advantageous further developments and embodiments are found in dependent claims 2 to 12. A plasticizing unit with a storage device according to the invention is specified in claim 8.

[0008] A key concept of the present invention is that the seals between the shaft and the bearing housing are designed as high-pressure sealing rings, such that the pressure fluid in the pressure chamber is maintained at or can be kept at a pressure of at least 10 bar. Preferably, an oil can be used as the pressure fluid. The pressure in the pressure chamber generates a counterforce that partially or completely compensates for the external force acting on the shaft. This allows significantly smaller rolling bearings to be used between the shaft and the bearing housing, resulting in considerable cost savings. In contrast to a conventional hydrostatic bearing, no oil flow is necessary, making the bearing device according to the invention extremely energy-efficient. Except in the case of leakage or expansion of components of the bearing device, no oil flow occurs. By simple variation or...By adjusting the pressure in the pressure chamber, the bearing device can be adapted to the most varied expected axial forces.

[0009] According to a first embodiment, the seals can be designed as high-pressure sealing rings such that the pressure fluid in the pressure chamber is at or can be maintained at a pressure of at least 30 bar. According to preferred embodiments, the seals can be designed as high-pressure sealing rings such that the pressure fluid in the pressure chamber is at or can be maintained at a pressure of 40 bar to 220 bar, preferably at a pressure of 60 bar to 200 bar, and particularly preferably at a pressure of 80 bar to 180 bar.

[0010] Between the shaft and the housing, one or more plain and / or rolling bearings may be provided within the pressure chamber. 77793-WO-KMT / Wl-Wl 04.07.2025

[0011] Furthermore, a pressure fluid source can be connected to the pressure chamber. However, it is also possible to connect and disconnect a pressure fluid source only when needed, for example, only for refilling with pressure fluid until a predetermined pressure is reached or restored in the pressure chamber. A pressure accumulator or a pump connected to a tank can preferably be used as the pressure fluid source. In principle, it is also possible to use a pump and pressure accumulator in combination.

[0012] According to a further development, a pressure sensor can be provided to measure the pressure prevailing in the pressure chamber. Using a suitable pressure control device, the pressure in the pressure chamber can be maintained within a predefined range. If the pressure falls below the set limit, new pressure fluid can be added, and / or if the pressure exceeds the set limit, existing pressure fluid can be released from the pressure chamber. The pressure control system can also react to changing axial forces acting on the shaft.

[0013] According to a further development, at least one bearing can be provided between the shaft and the housing, both within and outside the pressure chamber. At least one bearing within the pressure chamber can be designed as a shaft bearing for radial forces. Additionally or alternatively, at least one bearing outside the pressure chamber can be designed as a shaft bearing for axial and radial forces. Furthermore, at least one, preferably hardened, wear ring and / or at least one thrust washer, preferably with emergency running properties, can be provided between the shaft and the housing. A hardened wear ring, pressure-tightly shrunk onto a shaft segment, can be provided in the rotational area of ​​a high-pressure seal.In the event of a pressure drop in the pressure chamber and therefore insufficient back pressure, the shaft segment can be axially supported on a thrust washer with emergency running properties to prevent mechanical damage to the shaft segment and housing. 77793-WO-KMT / Wl-Wl 04.07.2025.

[0014] The bearing(s) located outside the pressure chamber would need to be lubricated separately, preferably with grease. This improved design offers the advantage of making the shaft or shaft segment less expensive to manufacture.

[0015] A preferred application of a bearing device according to the invention can be the plasticizing unit of an injection molding machine, with a rotary and linear drive screw mounted in a cylinder. For this purpose, a rotary drive and a linear drive are provided. A bearing device according to the invention can be provided between the screw and the drives. The shaft running through the bearing housing can be operatively connected at one end to the screw and at the opposite end to the rotary drive, whereas the bearing housing is operatively connected to the linear drive.

[0016] The invention will now be explained in more detail using exemplary embodiments and with reference to the figures. The figures show:

[0017] Fig. 1 first embodiment of a bearing device according to the invention

[0018] Fig. 2 second embodiment of a bearing device according to the invention

[0019] Fig. 3 third embodiment of a bearing device according to the invention

[0020] Fig. 4 Section of a plasticizing unit with a bearing device according to the invention as shown in Figure 3.

[0021] Figure 1 shows a first embodiment of a bearing device 1 according to the invention. The bearing housing 2 comprises a cylindrical housing part 2a and a cover 2b. A shaft 3 extends through the bearing housing 2, which is driven by rotation and is subjected to an axial force at least temporarily (see arrow A). Rotary seals 4a and 4b, designed as high-pressure sealing rings, are provided at both ends of the bearing device 1 between the shaft 3 and the bearing housing 2. High-pressure sealing ring means that these rotary seals or high-pressure sealing rings are designed for a pressure that is significantly higher than atmospheric pressure. For the preferred application, the high-pressure sealing rings are intended for a 77793-WO-KMT / Wl-Wl 04.07.2025

[0022] The bearing assembly 1 is designed for a pressure range of 40 bar to 220 bar, preferably 60 bar to 200 bar, and particularly preferably 80 bar to 180 bar. In the area between the two high-pressure sealing rings 4a and 4b, the bearing assembly 1 has a pressure chamber 5, which is filled with a pressure fluid, preferably an oil. The pressure chamber 5 is connected to a pressure medium source 8 via a channel 6 and a line 7. The pressure medium source 8 comprises a pressure accumulator 9, a valve 10, a pump 11, and a tank 12. A pressure can be generated in the pressure chamber 5 by means of the pressure medium source 8, which produces a force that counteracts the axial force. Depending on the pressure in the pressure chamber 5, the axial force can be compensated to a greater or lesser extent. Rolling bearings 13a and 13b are installed in the pressure chamber 5 between the shaft 3 and the housing 2. In each case, we are dealing with a shaft bearing for axial and radial forces.The oil in the pressure chamber permeates the rolling bearings and thus simultaneously acts as a lubricant in the components of the rolling bearing. The screw of a plasticizing unit and a linear drive for the screw are not shown. On the side of arrow A, the shaft 3 is operatively connected to the screw, and on the opposite side to a linear drive. Further details are shown in Figure 3. Optionally, an element 16 for axial preloading of the rolling bearings 13a and 13b may be installed. It ensures a positive or force-fit locking mechanism to prevent the shaft 3 from being hydraulically forced out of the housing 2.

[0023] Figure 2 shows another embodiment, in which identical parts of the bearing device 1 are provided with the same reference numerals. Therefore, a repetition of the description of these parts is unnecessary here. In contrast to Figure 1, a pressure regulating device 14 is now provided. Optionally, a pressure sensor 15 can also be installed in the bearing housing 2, the signals of which are evaluated by the pressure regulating device 14. Optionally, an element 16 for axial preloading of the rolling bearings 13a and 13b can also be installed in this embodiment.

[0024] Figure 3 shows a further embodiment of a bearing device according to the invention. In contrast to Figures 1 and 2, a combination 77793-WO-KMT / Wl-Wl 04.07.2025 of two different types of rolling bearings is used, namely a shaft bearing 17 for radial forces and a shaft bearing 18 for axial and radial forces. Furthermore, the shaft 19, which is operatively connected to the worm gear, is designed in two parts and comprises a shaft part 19a facing the rotary drive (not shown) and a shaft part 19b facing the worm gear (not shown). The bearing housing 20 is formed in one piece. A pressure chamber 5 is provided between the high-pressure sealing rings 4a and 4b, which is filled with a pressure fluid, preferably oil. The supply and discharge of the pressure fluid is effected via a channel 6, which is connected to, or can be connected to, a pressure medium source.Optionally, in this embodiment, a locking element 16' can be installed to secure the shaft 19 against hydraulic ejection from the housing 20 by means of a positive or force-fit. Furthermore, in this embodiment, the shaft segment 19a is not hardened and is instead provided with a hardened, pressure-tight wear ring 26, shrunk onto the shaft segment 19a, in the rotational area of ​​the high-pressure seal 4b. In the event of insufficient back pressure in the pressure chamber 5 to withstand the force A, the shaft segment 19b is axially supported on a thrust washer 27 with emergency running properties to prevent mechanical damage to the shaft segment 19b and the housing 20. In this embodiment, the shaft bearing 18 for axial and radial forces is located outside the pressure chamber 5 and must be lubricated separately, preferably with grease. This embodiment has the advantage that the shaft segment 19b is more economical to manufacture.Since the shaft bearing 18 is located outside the pressure chamber 5, an unexpected pressure drop in the pressure chamber 5 can lead to a reduction of the counterforce prevailing in the pressure chamber 5 and thus to increased wear on the shaft bearing 18.

[0025] Figure 4 shows a section of a plasticizing unit of an injection molding machine with a bearing device 1 according to the invention in the embodiment shown in Figure 3. The shaft section 19b is operatively connected to a screw flange 21, in particular by bolting. A rear end section of the screw 22 is rotationally fixed to the screw flange 21. The shaft section 19a is operatively connected to the rotor 23 of a rotary drive, for example via a splined connection. 77793-WO-KMT / Wl-Wl 04.07.2025

[0026] 24. The rotationally fixed bearing housing 20 is operatively connected to a linear drive 25 and can be moved forward by it in the injection direction (see arrows) or in the opposite direction (see also double arrow at reference numeral 25). The forward movement during the injection process can generate large axial forces acting on the shaft 19b, 19a (see also arrow A in Figures 1 to 3). A sufficiently high pressure in the pressure chamber 5 can maintain an opposing force, thus relieving the bearing assembly 1.

[0027] 77793-WO-KMT / Wl-Wl 04.07.2025

[0028] Reference symbol

[0029] 1 storage device

[0030] 2 bearing housings

[0031] 2a Cylindrical housing part

[0032] 2b Lid

[0033] 3rd wave

[0034] 4a First high-pressure sealing ring

[0035] 4b Second high-pressure sealing ring

[0036] 5 pressure chamber

[0037] 6-channel

[0038] 7 Pressure medium line

[0039] 8 Pressure source

[0040] 9 pressure accumulators

[0041] 10 valve

[0042] 11 Pump

[0043] 12 Tank

[0044] 13a First rolling bearing

[0045] 13b Second rolling bearing

[0046] 14 Pressure regulating device

[0047] 15 Pressure sensor

[0048] 16 Preload element

[0049] 16' locking element

[0050] 17 shaft bearings for radial forces

[0051] 18 shaft bearings for axial and radial forces

[0052] 19a First wave section

[0053] 19b Second wave section

[0054] 20 bearing housings of the second type

[0055] 21 snail flange

[0056] 22 snail

[0057] 23 Rotor of a rotary drive

[0058] 24 Keyway gearing

[0059] 25 Linear drive

[0060] 26 Wear ring

[0061] 27 Thrust washer

Claims

77793-WO-KMT / Wl-Wl 04.07.2025 Claims 1. Bearing device for a rotary-driven and axially loaded shaft, comprising a bearing housing through which the shaft is passed, wherein at least two seals spaced apart from each other in the axial direction are provided between the shaft and the bearing housing, wherein a pressure chamber filled with a pressure fluid, in particular oil, is provided in the area between the seals between the shaft and the bearing housing, characterized in that the seals are designed as high-pressure sealing rings, such that the pressure fluid in the pressure chamber is or can be kept under a pressure of at least 10 bar.

2. Bearing device according to claim 1, characterized in that the seals are designed as high-pressure sealing rings such that the pressure fluid in the pressure chamber is or can be kept under a pressure of at least 30 bar.

3. Bearing device according to one of the preceding claims, characterized in that the seals are designed as high-pressure sealing rings, such that the pressure fluid in the pressure chamber is or can be maintained under a pressure of 40 bar to 220 bar, preferably under a pressure of 60 bar to 200 bar, particularly preferably under a pressure of 80 bar to 180 bar.

4. Bearing device according to one of the preceding claims, characterized in that one or more sliding and / or rolling bearings are provided between the shaft and the housing within the pressure chamber.

5. Storage device according to one of the preceding claims, characterized in that 77793-WO-KMT / Wl-Wl 04.07.2025 a pressure fluid source is connected or can be connected to the pressure medium chamber.

6. Storage device according to claim 6, characterized in that a pressure accumulator and / or a pump is provided as the pressure fluid source.

7. Storage device according to claim 5 or 6, characterized in that a pressure sensor is provided with which the pressure prevailing in the pressure chamber can be measured and that a pressure control device is provided with which the pressure prevailing in the pressure chamber can be maintained within a predefinable pressure range, wherein new pressure fluid can be supplied when the pressure falls below the set limit, and / or wherein existing pressure fluid can be drained from the pressure chamber when the pressure exceeds the set limit.

8. Bearing device according to one of the preceding claims, characterized in that at least one bearing is provided between the shaft and the housing inside the pressure chamber and at least one bearing is provided outside the pressure chamber.

9. Bearing device according to claim 8, characterized in that at least one bearing in the pressure chamber is designed as a shaft bearing for radial forces, and / or that at least one bearing outside the pressure chamber is designed as a shaft bearing for axial and radial forces.

10. Bearing device according to one of the preceding claims, characterized in that at least one, preferably hardened, wear ring and / or at least one thrust washer, preferably with emergency running properties, is provided between the shaft and the housing. 77793-WO-KMT / Wl-Wl 04.07.2025 11. Plasticizing unit of an injection molding machine with a rotatable and linearly driven screw mounted in a cylinder, with a rotary drive and with a linear drive, wherein a bearing device according to one of the preceding claims is provided between the screw and the drives.

12. Plasticizing unit according to claim 11, characterized in that the shaft extending through the bearing housing is operatively connected at one end to the worm and at its opposite end to the rotary drive, and that the bearing housing is operatively connected to the linear drive.

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