EP1601522A1

EP1601522A1 - Electrical pressing device

Info

Publication number: EP1601522A1
Application number: EP03769232A
Authority: EP
Inventors: Ralf Kosan; Kai Seelig
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-11-01
Filing date: 2003-10-09
Publication date: 2005-12-07
Also published as: CA2504221A1; DE20218396U1; DE10251387A1; DE10251387B4; KR20050074510A; BR0315838A; JP2006504533A; WO2004039569A1; AU2003277819A1

Abstract

The invention relates to an electrical pressing device comprising an electric motor (2); a step-up gear (8); a spindle drive (66) embodied as a threaded roller screw drive, the threaded spindle (14) thereof being connected to the step-up gear (8), and the threaded nut (16) thereof being guided in a cylindrical housing (22) in a rotationally fixed and axially displaceable manner and being connected to a pressing tool, for converting a rotational movement of the electric motor (2) into a linear movement of the pressing tool; a displacement sensor (30) for determining the distance covered by the pressing tool; and a sensor (10) for determining the compressive force of the pressing tool. The threaded spindle (14) is mounted in the housing by means of a pre-stressed set of angular ball bearings (12), the first angular ball bearing (46) being used to absorb tractive forces and the second angular ball bearing (48) being used to absorb compressive forces. The internal rings of the angular ball bearings (46, 48) are clamped next to each other, against a shaft shoulder (54) of the threaded spindle (14), by means of a shaft nut (52), and the outer rings of the angular ball bearings (46, 48) are clamped next to each other, against a projection (58) of the housing, by means of a housing nut (56), such that the inventive device can absorb essentially identical tractive or pressure forces, without axial play.

Description

Electric press device

The invention relates to an electrical pressing device with an electric motor, a transmission gear, a spindle drive designed as a threaded roller screw drive, the threaded spindle of which is connected to the transmission gear and whose threaded nut is rotatably and axially displaceably filled in a cylindrical housing and connected to a pressing tool Conversion of a rotary movement of the electric motor into a linear movement of the pressing tool, a displacement sensor for determining the distance traveled by the pressing tool and a sensor for determining the pressing force of the pressing tool.

Such a pressing device is known from DE 100 11 859 C2, in which the threaded spindle is supported in the axial direction with respect to the housing by a flange shoulder and a tapered roller bearing. The tapered roller bearing is only secured against axial displacement on the threaded spindle by means of a locking ring and can transmit practically no axial forces in the pulling direction. This is also not necessary in the known press-in device since only press forces are to be generated in one direction (pressure direction).

The invention has set itself the task of further developing an electrical pressing device of the type mentioned in such a way that pressing forces (tensile and compressive forces) can be generated, the smallest possible diameter of the cylindrical housing is aimed.

Another object of the invention is to provide an electrical pressing device which can be freely selected in terms of its axial position on a machine frame or the like. can be fixed. This is not possible in the known pressing device, since there the housing is provided with a fastening flange, so that the pressing device can only be fixed in a predetermined position.

- 25.161 / 185 - Another object of the invention is to make the guidance of the threaded nut of the spindle drive, which is non-rotatable and axially displaceable with respect to the housing, structurally simpler.

The first-mentioned object of the invention is achieved by an electric pressing device with an electric motor, a transmission gear, a spindle drive designed as a thread roller screw drive, the threaded spindle of which is connected to the transmission gear and whose threaded nut is rotatably and axially displaceably guided in a cylindrical housing and connected to a pressing tool Conversion of a rotary movement of the electric motor into a linear movement of the pressing tool, a displacement sensor for determining the distance traveled by the pressing tool and a sensor for determining the pressing force of the pressing tool, wherein the pressing device is characterized in that the threaded spindle by means of a preloaded angular contact ball bearing set, the first (see ) Angular contact ball bearing for increasing tensile forces and its second angular contact ball bearing is (are) suitable for absorbing compressive forces, is mounted in the housing, the inner rings of the angular contact ball are supported with a shaft nut against one another against a shaft shoulder of the threaded spindle and the outer rings of the angular contact ball bearings are clamped against one another with a housing nut against a housing shoulder, so that essentially equal tensile or compressive forces can be absorbed without axial play.

It can be provided that the angular contact ball bearing set has two first and two second angular contact ball bearings.

It is expediently provided that the transmission gear is designed as a multi-stage transmission, the transmission gear having a transmission ratio of e.g. can have i = 5.

It is preferably provided that the electric motor is electrically controlled and has an angle encoder on the motor shaft, with a device being provided to determine the path of the pressing tool based on the angle signals of the angle encoder, the gear ratio of the gear mechanism and the thread pitch of the spindle drive. It is expediently provided that a torque sensor is arranged between an output shaft of the transmission gear and the threaded spindle. The torque sensor can have a transmitter for contactless transmission of measured values. The torque sensor is preferably easily accessible and interchangeable to adapt to different pressing forces. This makes it possible to largely utilize different measuring ranges of torque sensors even with different pressing forces, so that the measuring accuracy increases.

A lockable housing opening is expediently provided for access to the torque sensor.

The invention further provides that a motor brake which is in the de-energized state and released under current is arranged on the motor shaft. This ensures that movement of the pressing device is prevented even in the case of a power failure in the case of a transmission that does not automatically block.

It is expediently provided that a spring-loaded stop is provided between the threaded nut and the housing to determine the zero position of the displacement measurement.

The stop can be designed as a spring-loaded ring on the threaded nut.

The threaded spindle preferably has a multi-start, in particular a 5-start thread.

The threaded nut can be fixed in an axially stepped receiving sleeve, which is guided in the housing in a rotationally fixed and axially displaceable manner.

In a preferred embodiment it is provided that the receiving sleeve is connected or forms an inner sleeve of an axial guide guide, the outer sleeve of which is non-rotatably connected to the housing. The receiving sleeve can have a cylindrical receiving part of a relatively large diameter and a sleeve of smaller diameter screwed to it, forming the press ram.

The housing preferably has an outer cylindrical clamping surface for fixing the pressing device to a freely selectable axial clamping position.

For this purpose, a double-cone clamping set can be arranged on the clamping surface.

Further advantages and features of the invention result from the following description of a preferred embodiment, reference being made to a drawing in which

Fig. 1 shows a partially sectioned side view of a pressing device according to the invention;

FIG. 2 shows an enlarged detail from FIG. 1 in the area of the angular contact ball bearing set;

3 shows an enlarged detail from FIG. 1 in the region of the axial ball recirculation guide;

Figure 4 shows a cross-sectional view along line IN - IN in Figures 1 and 2, respectively; and

Figure 5 shows a cross-sectional view along line N-N in Figures 1 and 3, respectively.

First of all, reference is made to FIG. 1, which shows an electrical pressing device according to the present invention in a partially sectioned side view. Essential components of the pressing device are an electric motor 2 with a motor brake 6 acting on its motor shaft 4, a transmission gear 8, a torque sensor 10, an angular contact ball bearing set 12 in which a threaded spindle 14 is mounted, which together with a threaded nut 16 forms a spindle drive 66, and a receiving sleeve 18 holding the threaded nut 16, which in turn is mounted in an axial ball recirculation guide 20 which which is supported in a cylindrical housing 22, which has a cylindrical outer clamping surface 24 for fixing in a freely selectable position on a machine part 26 or the like, by means of a clamping set 28.

An angle encoder 30 is arranged on the motor shaft 4 as an absolute measuring value transmitter, and a resolver 32 is provided in order to evaluate the signals of the angle encoder in order to obtain a path signal. For this purpose, the transmission ratio of the transmission gear 8 and the thread pitch of the spindle drive 66 (threaded spindle 14, threaded nut 16) are used in a manner known per se.

The motor brake 6 is designed in such a way that it engages in the de-energized state by means of springs and prevents rotation of the motor shaft, but is released when the power supply is present.

The transmission gear 8 could be designed as a planetary gear, but in the preferred embodiment is a multi-stage gear with a gear ratio of e.g. i = 5 trained. An input shaft 34 of the transmission gear 8 is connected to the motor shaft 4, while an output shaft 36 of the transmission gear is connected to the threaded spindle 14 and carries the torque sensor 10. The torque sensor 10 is provided with a transmitter, so that measurement values can be transmitted without wire or sliding contact. The torque sensor 10 is relatively easily accessible via a closable housing opening 38 and can be easily replaced, so that a torque sensor adapted to a pressing force to be achieved in a particular case can be used in each case. This has the advantage that with a torque sensor adapted to a certain maximum torque pressing force the measuring range of the torque sensor is largely used, so that the measuring accuracy is maximized. As a result, an accuracy of less than 1% of the maximum or final value and thus also a corresponding accuracy when setting a desired pressing force, which is determined from the torque, can be achieved.

The threaded spindle 14, with reference now also to FIGS. 2 and 4, is mounted in the housing 22 by means of an inclined ball bearing set designated as a whole, which in the present case has a bearing sleeve 40 and an outer guide 42 screwed to it.

The angular contact ball bearing set 12 in the embodiment described here consists of a total of four angular contact ball bearings, each of which can absorb the same axial and radial forces, which is indicated by load action lines 44 running at 45 ° to the longitudinal axis 50.

Two first angular contact ball bearings 46 are arranged to absorb tensile forces (acting to the left in FIG. 1, 2) and two second angular contact ball bearings 48 each to absorb compressive forces (acting to the right in FIG. 1, 2). The inner rings of the angular contact ball bearings are clamped directly against one another against a shaft shoulder 54 of the threaded spindle by means of a shaft nut 52, while the outer rings of the angular contact ball bearings are clamped against one another against a housing shoulder 58 in a corresponding manner by means of a housing nut 56. The angular contact ball bearings are manufactured in such a way that there is no more play when the shaft and housing nuts are tightened, but on the contrary, a preload of the two oppositely aligned bearing pairs 46 and 48 is present so that i. w. equally large tensile or compressive forces can be absorbed without axial play occurring. The advantage of this design is that no special dimensional tolerances in the area of the bearing sleeve or the threaded spindle have to be observed, as far as the axial dimensions are concerned, since the inner and outer rings are firmly tightened with the shaft and housing nuts for a perfect, play-free Function is enough.

Following the shaft shoulder 54, the threaded spindle 14 is provided with a five-thread section 60, the length of which is dimensioned such that the desired pressing tasks can be carried out.

The threaded spindle 14 with its threaded section 60 and the threaded nut 16 and rollers forms the spindle drive 66, which is designed as a threaded roller screw drive (also referred to as a planetary roller screw drive) is. Fastening screws 70 fix the threaded nut 16 within the receiving sleeve 18 via a fastening ring 72, whereby on the fastening ring 72 or the receiving sleeve 18, a ring 76 spring-loaded by means of compression springs 74 forms a spring-loaded stop. When the spindle drive moves backward (to the right), the threaded nut with the ring 76 runs against the housing shoulder 58 of the bearing sleeve 40, as a result of which the torque sensor 10 detects an increase in torque and a zero point detection is thereby possible.

The receiving sleeve 18 is formed from a receiving part 18a which receives the threaded nut 16 and which is of relatively large diameter and a sleeve 18b of smaller diameter which is screwed thereto and forms the press ram. The sleeve 18b is mounted in an inner sleeve of the axial ball guide 20 or forms it (FIGS. 3 and 5), the outer sleeve 21 of which being fixed axially immovably in the housing or the outer guide 42 by means of retaining rings 77 and connected to it in a rotationally fixed manner by means of a key 78 is. A press tool, not shown, is held at the end of the sleeve 18b.

The clamping set 28 has conical clamping elements with which the pressing device can be fixed on the outer guide 42 in a freely selectable axial clamping position on the machine part 26.

Reference sign list

Electric motor 52 shaft nut

Motor shaft 54 shaft shoulder

Motor brake 56 housing nut

Transmission gearbox 58 shoulder

Torque sensor 60 thread section

Angular contact ball bearing set 66 spindle drive

Threaded spindle 68 key

Threaded nut 70 fastening screw

Receiving sleeve 72 mounting ring a receiving part 74 compression spring b sleeve 76 ring

AxialJ igelumlaufführung 77 circlip

Outer sleeve 78 key

casing

clamping surface

machinery

clamping set

angle encoder

resolver

input shaft

output shaft

Housing opening bearing sleeve

Außenfuhrung

Load action line first angular contact ball bearing second angular contact ball bearing

longitudinal axis

Claims

claims

1. Electrical pressing device with an electric motor (2), a transmission gear (8), a spindle drive (66) designed as a threaded roller screw drive, the threaded spindle (14) of which is connected to the transmission gear (8) and whose threaded nut (16) is non-rotatable and axially displaceable in a cylindrical housing (22) and connected to a pressing tool for converting a rotary movement of the electric motor (2) into a linear movement of the pressing tool, a displacement sensor (30) for determining the distance traveled by the pressing tool and a sensor (10) for determining the pressing force of the pressing tool, characterized in that the threaded spindle (14) by means of a preloaded angular contact ball bearing set (12), the first (s) angular contact ball bearing (46) for absorbing tensile forces and the second (s) angular contact ball bearing (48) suitable for absorbing compressive forces is (are) mounted in the housing (22), the inner rings of the angular contact ball bearings with a shaft nut (52) lying against one another against a shaft shoulder (54) of the threaded spindle (14) and the outer rings of the angular contact ball bearings (46, 48) with a housing nut (56) lying against each other against a housing shoulder (58), so that i.w. equal tensile or compressive forces can be absorbed without axial play.

2. Press device according to claim 1, characterized in that the angular contact ball bearing set (12) has two first (46) and two second angular contact ball bearings (48).

3. Press device according to claim 1 or 2, characterized in that the transmission gear (8) is designed as a multi-stage gear.

4. Press device according to one of the preceding claims, characterized in that the transmission gear (8) has a transmission ratio of e.g. i = 5.

5. Press device according to one of the preceding claims, characterized in that the electric motor (2) is electrically controlled and has an angle encoder (30) on the motor shaft (4), wherein a device (32) is provided to cover the path traveled by the pressing tool based on the angle signals of the angle encoder (30), the translation To determine the ratio of the transmission gear (8) and the thread pitch of the spindle drive (66).

6. Press device according to one of the preceding claims, characterized in that a torque sensor (10) is arranged between an output shaft (36) of the transmission gear (8) and the threaded spindle (14).

7. Press device according to claim 6, characterized in that the torque sensor (10) has a transmitter for contactless transmission of measured values.

8. Press device according to claim 6 or 7, characterized in that the torque sensor (10) is easily accessible and interchangeable to adapt to different pressing forces.

9. Press device according to one of claims 6 to 8, characterized in that a closable housing opening (38) is provided for access to the torque sensor (10).

10. Press device according to one of the preceding claims, characterized in that a motor brake (6) which is in the de-energized state and is under current is arranged on the motor shaft (4).

11. Press device according to one of the preceding claims, characterized in that a spring-loaded stop (76) is formed between the threaded nut (16) and the housing (22) for determining the zero position of the displacement measurement.

12. Press device according to claim 11, characterized in that the stop is designed as a spring-loaded ring (76) on the threaded nut (16).

13. Press device according to one of the preceding claims, characterized in that the threaded spindle (14) is a multi-start, e.g. has five threads.

14. Press device according to one of the preceding claims, characterized in that the threaded nut (16) is fixed in an axially stepped receiving sleeve (18) which is guided in the housing (22) in a rotationally fixed and axially displaceable manner.

15. Press device according to claim 14, characterized in that the Aufiiahmehülse (18) with an inner sleeve of an axial ball recirculation guide (20) is connected or forms the latter, the outer sleeve (21) is rotatably connected to the housing (22).

16. Press device according to claim 14 or 15, characterized in that the receiving sleeve (18) has a cylindrical Aufiiahmeteil (18a) of relatively large diameter and a screwed therewith, the press ram forming sleeve (18b) has a smaller diameter.

17. Press device according to one of the preceding claims, characterized in that the housing (22) has an outer cylindrical clamping surface (24) for fixing the pressing device at a freely selectable axial clamping position.

18. Press device according to claim 17, characterized in that a double-cone clamping set (28) is arranged on the clamping surface (24).