CN111741833B

CN111741833B - Rotary table with clamping brake

Info

Publication number: CN111741833B
Application number: CN201980014545.9A
Authority: CN
Inventors: M·申科
Original assignee: Fibro GmbH
Current assignee: Fibro GmbH
Priority date: 2018-04-19
Filing date: 2019-04-09
Publication date: 2022-10-25
Anticipated expiration: 2039-04-09
Also published as: KR20200116994A; DE202018102467U1; CN111741833A; JP2021515707A; KR20230113658A; JP7308219B2; SG11202008072TA; EP3727744A1; WO2019201677A1; DE102018109430A1

Abstract

The invention relates to a rotary table comprising a stationary housing for accommodating a workpiece and an indexing plate which is rotatably supported relative to the stationary housing about a central axis of rotation, wherein at least one clamping brake which can be actuated from a clamping position into a non-clamping position is formed between the stationary housing and the rotatably mounted indexing plate, and wherein the clamping brake comprises a first spring element and a second spring element for actuating a brake pad, wherein the second spring element can exert at least one force on the brake pad which is controllable in the direction of the spring force of the first spring element, more particularly adjustable in its magnitude.

Description

Rotary table with clamping brake

The specification is as follows:

the invention relates to a rotary table with a braking device, comprising in particular: a fixed housing for accommodating a workpiece and an indexing plate which is rotatably supported relative to the fixed housing about a central axis of rotation, wherein at least one clamping brake which can be actuated from a clamping position into a non-clamping position is formed between the fixed housing and the rotatably supported indexing plate, and wherein the clamping brake comprises a spring element for actuating a brake pad and means for applying an adjustable force onto the spring element, wherein the means can apply at least one force directly or indirectly onto the brake pad, which force is controllable in the direction of the spring force of the spring element, more particularly adjustable in its magnitude.

A rotary table for positioning a workpiece according to the technical field of the present invention is already known from DE 20 2014 103 937 U1. Rotary tables are used in particular as swivel or positioning axes and as work piece carriers in machine tools and in the field of assembly tasks. The rotary table unit is now integrated as a basic component in a high-precision machine. For example, rotary tables for machine tools are known which are indexed sequentially and clamped after each partial step, so that the machining of the workpiece can take place in defined positions while the rotary table is at rest. Typically, the clamping of these rotary tables is performed by one or more clamping devices acting on or near the outer table circumference. Such clamping devices are purely mechanically or hydraulically actuated. The actuation generates a corresponding force, which is introduced into the component of the table. For example, if the plate of the rotary table is directly clamped, the plate of the table may warp, which results in positional inaccuracy. In this type of clamping it is disadvantageous and problematic that the clamping means engage only at individual points, which means that very large point forces are required to fix the table in position, which in turn may warp the table.

Another drawback of the known clamping device is the lack of safety for the operator, since the clamping action stops in case of a failure of the electrical and/or mechanical supply. The safety device therefore requires additional expenditure, in particular at the high weight and moment of inertia of the machine.

The problem underlying the present invention is therefore to overcome the aforementioned drawbacks and to provide a rotary table which provides improved clamping with increased safety measures against electrical and/or mechanical supply failures and which can be operated at the same time with high positioning accuracy.

These problems are solved by combining the features according to claim 1.

According to the invention, a rotary table is therefore proposed, which comprises a stationary housing for accommodating a workpiece and an indexing plate which is mounted rotatably relative to the stationary housing about a central axis of rotation. At least one clamping detent, which can be actuated from a clamped position into an undamped position, is formed between the stationary housing and the rotatably mounted indexing plate. The pinch brake comprises a spring element for actuating a brake pad and means for applying an adjustable force to the spring element. Furthermore, the device can apply at least one force directly or indirectly to the brake pad, which force is controllable in the direction of the spring force of the first spring element, more particularly adjustable in its magnitude. In this case, it is advantageous if the clamping brake can retard the rotation of the index plate or fix the index plate against rotation relative to the fixed housing. This arrangement improves the clamping, which means that the system can be operated with a higher positioning accuracy.

In an advantageous embodiment variant, it is provided that the device can also exert a force on the brake pad, which force can be controlled to act against the spring force of the spring element. In this way, the rotatably supported indexing plate can be released from the clamping as soon as the controllable force exceeds the spring force of the spring element.

Preferably, the rotary table is designed such that the clamping brake has a brake disc and a brake spring. Wherein the braking spring represents the spring element.

In an exemplary embodiment of the invention, it is advantageously provided that the brake spring is designed to be in the clamping brake under a pretension such that, in a state in which no voltage is applied to the rotary table and its movable device or the device is not ready for operation, or alternatively also in a state in which the device is ready for operation, the spring force presses the brake pad against the brake disc and the clamping brake is in the clamping position. The default state of the clamping brake is thus the clamping position, which means that no further force has to be applied to fix the position of the index plate, for example for mounting a workpiece. This condition is called "normally closed" because the brake always blocks the rotary table firmly, regardless of the presence or absence of the hydraulic brake, the readiness for operation, or even in the event of a voltage supply or operating device power failure.

Furthermore, embodiments are advantageous in which a force from the device is applied to the brake pad for moving the clamping brake from the clamping position to the non-clamping position. By activating such a force (preferably a force generated hydraulically or pneumatically by means of e.g. a hydraulic piston), the spring force of the force against the spring element acts on the brake pad. This opens the clamping brake to such an extent that the brake pads and the brake disc are no longer in contact with each other.

In a further advantageous variant, it is provided that, in addition to the spring force of the spring element, a force (preferably a hydraulically or pneumatically generated force) is applied to the brake pad in the direction of the spring force for completely blocking the rotational movement of the indexing plate. By applying a further force in the direction of the spring force, the clamping brake increases the resistance against rotation of the indexing plate, whereby a higher force can act on the indexing plate while mounting a workpiece (e.g. without rotation of the indexing plate). This also results in a particularly effective braking capability, especially when high masses have to be brought to rest, which takes too long in the case of mechanical spring brakes alone. For static conditions, the clamping force can be adjusted as needed. In an alternative embodiment, the device uses the spring element to press the brake pad against a second spring element, and the second spring element presses the brake disc against the housing.

In an advantageous application embodiment, the spring force and the braking force and the reaction force act parallel to the central axis of rotation.

In an embodiment variant, the rotary table according to the invention is designed such that the braking force of the brake pads acts directly on the index plate. This is advantageous because no further braking force losses are caused by the coupling element.

It is further advantageous that fluid conducting lines for hydraulic or pneumatic devices are designed within the fixed housing and the indexing plate for actuating the force of the device. This proves advantageous because the fluid conducting lines then extend within the rotary table and, therefore, additional sources of danger are avoided, which lines rotate with the index plate or extend outside the rotary table. The action of the spring element is still securely maintained if the fluid supply fails, for example due to a line break.

In a development of the inventive rotary table according to the invention, it is further provided that the force of the device acts directly on or at the spring element (so to speak connected in series with the spring element) for reducing or releasing the braking force.

In a preferred embodiment of the invention, the indexing plate is thus blocked by the spring element when the device is inactive or in the event of failure of the action of the device. The operational safety of the rotary table is therefore significantly increased, since the indexing plate cannot rotate in the event of a malfunction.

In addition, the actor failure is a state in which the pneumatic device for generating the actor's force is inactive.

In addition, the failure of the device is a state in which the control electronics for controlling the spring force of the device are inactive.

Further advantageous developments of the invention are characterized in the dependent claims and/or are described in more detail by the figures in connection with the description of preferred embodiments of the invention. The figures show:

FIG. 1 is a cross-sectional view of a rotary table with a pinch brake

FIG. 2 schematic view of a clamping brake for a rotary table

FIG. 3 is a schematic view of an alternative embodiment of a pinch brake for a rotary table

In the following, the invention is described with reference to fig. 1 and 2 on the basis of an exemplary embodiment, wherein the same reference numerals indicate the same structural and/or functional features.

Fig. 1 shows a sectional view of a rotary table 1 with a clamping brake 4. The rotary table comprises a stationary housing 2 for accommodating a workpiece and an index plate 3, said index plate 3 being rotatably supported relative to the stationary housing 2 about a central axis of rotation Z. In which two clamping detents 4 which can be actuated from a clamping position into a non-clamping position are designed between the stationary housing 2 and the rotatably mounted indexing plate 3. Furthermore, the respective clamping brake 4 comprises a spring element 5 for actuating a brake pad 7 and a device 6 for applying an adjustable force to the spring element 5.

The pinch brake 4 has a brake disc 8 and a brake spring 9. The brake spring 9 represents the first spring element 5. The clamping brake 4 is shown once in the clamped position and once in the undamped position. The part of the clamping brake 4 consisting of the brake pad 7 and the brake spring 9 is fixed to the stationary housing 2 by means of fastening means. Conversely, the brake disc 8 of the clamping brake 4 is attached to the indexing plate 3 by means of fastening means. The corresponding fastening means are designed, for example, as screws.

When the brake spring 9 is installed in the pinch brake 4 under pretension, the pinch brake 4 in the pinch position (in the "normally closed" state) is in a state in which the spring force presses the brake pad 7 against the brake disc 8.

In the other clamping brake 4, a force of the device 6 (preferably a hydraulically or pneumatically generated force) is activated, which counteracts the spring force F of the spring element 5, thus displacing the brake pad 7 from the clamping position to the non-clamping position. The direction of movement of the brake pad 7 from the clamping position to the non-clamping position extends parallel to the axis of rotation Z.

In addition, fluid conducting lines for hydraulic or pneumatic devices are designed within the stationary housing 2 and the index plate 3 for activating the force of the device 6.

Fig. 2 shows a schematic view of a clamping brake 4 for the rotary table 1. The clamping brake 4 is designed between the fixed housing 2 and the rotatably mounted indexing plate 3 and comprises a brake pad 7, a brake disc 8, a spring element 5 and a device 6.

Furthermore, the schematic from fig. 2 has a fluid conducting line 10 which leads to the device 6 of the pinch brake 4.

The brake pads 7 are movably supported in the clamping brake 4 such that said brake pads 7 can be moved back and forth between the stationary housing 2 and the rotatably mounted indexing plate 3 in a vertical direction parallel to the central axis of rotation. The displacement of the brake pad 7 is caused by the force acting on the brake pad 7. The spring force of the spring element 5 acts in the direction of the index plate 3. When the device 6, in this example shown as a hydraulically actuated piston, is connected in series to the spring element 5, the forces of the two components add to or subtract from each other. The direction of action or the magnitude of the force of the adjustable means 6 can be adjusted by means of fluid conducting lines leading to the means 6.

Fig. 3 shows a schematic view of an alternative embodiment of a clamping brake 4 for the rotary table 1. The clamping brake 4 is designed between the stationary housing 2 and the rotatably mounted indexing plate 3 and comprises a brake pad 7, a brake disc 8, a spring element 5, a second spring element 11 and a device 6, i.e. a piston.

Furthermore, the schematic from fig. 3 has two

fluid conducting lines

10a, 10b which lead to the piston 6 of the pinch brake 4. For braking, the spring element 5 presses the brake pad 7 against the second spring element 11. Thereby, the second spring element 11 presses the brake disc 8 against the housing 2 and the rotating indexing plate 3 decelerates to a standstill.

After the braking process, the dividing plate 3 is connected to the brake disk 8 in an inactive manner and without play. To increase the holding force, the brake disk 8 is clamped between the second spring element 11 and the housing 2. To increase the clamping or braking force, fluid is pressed through the fluid conducting line 10b. The force acts on the piston 6 by means of the resulting pressure against the piston 6, said piston 6 pressing against the brake pad 7 and increasing the clamping or braking force. In addition, pressure is applied through the fluid conducting line 10a for releasing the clamping or braking force. The resulting pressure against the device 6 causes a force to act against the piston 6, which piston 6 presses against the spring element 5. If the force of the spring element 5 is exceeded, the brake disc 8 is released and the indexing plate 3 can rotate.

The embodiments of the invention are not limited to the foregoing preferred exemplary embodiments. On the contrary, variants are conceivable which use the solution shown here, even if they lead to fundamentally different embodiments.

Claims

1. A rotary table (1) comprising: a stationary housing (2) for accommodating a workpiece and an indexing plate (3), the indexing plate (3) being rotatably mounted relative to the stationary housing (2) about a central axis of rotation (Z), wherein at least one clamping brake (4) which can be actuated from a clamping position into a non-clamping position is formed between the stationary housing (2) and the rotatably mounted indexing plate (3), and wherein the clamping brake (4) comprises a spring element (5) for actuating a brake pad (7) and means (6) for applying an adjustable force onto the spring element (5), wherein the means (6) can apply at least one force directly or indirectly onto the brake pad (7), the force being controllable in the direction of the spring force of the spring element (5); the clamping brake (4) has a brake disk (8) and a brake spring (9); said device (6) pressing said brake pad (7) against a second spring element (11) by means of said spring element (5) and in that: the second spring element (11) presses the brake disk (8) against the stationary housing (2), the braking force of the brake pad (7) acting directly on the dividing plate (3).

2. Swivel table (1) according to claim 1, wherein the force is adjustable in magnitude in the direction of the spring force of the spring element (5).

3. Rotary table (1) according to claim 1, wherein the means (6) are further capable of exerting a force on the brake pad (7), which force can be controlled to act against the spring force of the spring element (5).

4. Rotating table (1) according to claim 1, characterized in that: the brake spring (9) represents the spring element (5).

5. The rotary table (1) according to claim 1, characterized in that: the brake spring (9) is designed to be in the clamping brake (4) under a preload such that the spring force (F) presses the brake pad (7) against the brake disk (8) and the clamping brake (4) is in the clamping position.

6. Rotating table (1) according to claim 1, characterized in that: the force of the device (6) acting against the spring force (F) of the spring element (5) is activated and consists in: an activated force is applied to the brake pads (7) for displacing the clamping brake (4) from the clamping position to the non-clamping position.

7. Rotary table (1) according to claim 6, wherein the force of the device (6) counteracting the spring force (F) of the spring element (5) is a hydraulically or pneumatically generated force.

8. Rotating table (1) according to any of claims 1 to 7, characterized in that: a force is applied to the brake pad (7) in the direction of the spring force (F) for completely blocking the rotational movement of the index plate (3).

9. Rotary table (1) according to claim 8, wherein the force is a hydraulically or pneumatically generated force.

10. Rotating table (1) according to claim 6, characterized in that: the spring force and the braking force and the force of the device (6) acting against the spring force (F) of the spring element (5) act parallel to the central axis of rotation (Z).

11. Rotating table (1) according to any one of claims 1 to 7, characterized in that: fluid conducting lines (10) for hydraulic or pneumatic devices are designed in the stationary housing (2) and the indexing plate (3) for activating the spring force of the device (6).

12. The rotary table (1) according to claim 10, characterized in that: the force of the device (6) acts directly on the spring element (5) or at the spring element (5) for reducing or releasing the braking force.

13. The rotary table (1) according to claim 11, characterized in that: the spring element (5) blocks the index plate (3) when the device (6) is inactive or in the event of failure of the action of the device (6).

14. Rotating table (1) according to claim 13, characterized in that: the failure of the device (6) is a state in which the pneumatic means for generating the force of the device (6) are inactive.

15. The rotary table (1) according to claim 13, characterized in that: the failure of the device (6) is a state in which the control electronics for controlling the spring force of the device (6) are inactive.