WO2020174272A1

WO2020174272A1 - Electrospindle comprising a proximity sensor for its traction shaft

Info

Publication number: WO2020174272A1
Application number: PCT/IB2019/053482
Authority: WO
Inventors: Francesca SACCARDO; Marco POVOLO; Massimo SACCHIERO
Original assignee: Saccardo Elettromeccanica S.R.L.
Priority date: 2019-02-27
Filing date: 2019-04-29
Publication date: 2020-09-03
Also published as: IT201900002847A1; CN111886100A

Abstract

An electrospindle comprising: a motor (2); a traction shaft (3) operatively coupled to the motor (2) having a first end (4) configured to receive and hold a tool; a pneumatic circuit for translating the traction shaft (3) to arrange it according to a first work configuration, in which the movement of the tool is allowed, and a second rest configuration in which the movement of the tool is denied; a joint (6) stably coupled to a second end (7) of the traction shaft (3) and provided with a fitting (8) for connection to a water delivery pipe. The joint (6) comprises: a cover body (20) operatively coupled to the traction shaft (3) by means of rotatable means (10) so as to prevent its rotation and allow its translation along the longitudinal development axis (X); a signalling element (21) associated with the cover body (20); one or more proximity sensors (22) of the signalling element (21) to determine whether the traction shaft (3) is in the first work configuration or in the second rest configuration.

Description

ELECTROSPINDLE COMPRISING A PROXIMITY SENSOR

FOR ITS TRACTION SHAFT

D E S C R I P T I O N

Field of application

The present invention is applicable to the field of industrial machining operations and, in particular, concerns machine tools.

More in detail, the present invention relates to an electrospindle for industrial machining operations.

Background art

It is known that material machining operations in the industrial field now take place almost exclusively by electric tools. Operations such as cutting, bending, milling, drilling or other, in fact, typically take place by means of special machines equipped with the appropriate tools to perform said machining operations.

The aforesaid electric tools in numerous cases comprise electrospindles, i.e. motorized devices whose motor shaft has an end configured to retain radial and/or axial machining tools.

Among the electrospindles a type is known where there is a traction shaft arranged to slide inside the motor shaft. In these, the tool is fixed to the traction shaft by means of a gripper. More in detail, the traction shaft is movable inside the electrospindle according to its longitudinal development axis so that it can be arranged according to a first recessed work configuration, in which the tool is retained and can therefore be moved, and a second rest configuration, in which the traction shaft is at least partially extracted allowing the gripper to open and release the tool for its replacement or maintenance.

Known electrospindles often also comprise a joint firmly coupled to the second end of the traction shaft and provided with a fitting for connection to a water delivery pipe. The latter is used by the electrospindle for certain machining operations.

It is evident that the electrospindles described above are dangerous because in the rest configuration, that is when the gripper is open and the tool is not correctly retained, it is possible that there is an incorrect start-up. To overcome this drawback, according to the prior art, special signalling devices are added which are typically placed side by side with the aforementioned joint. These signalling devices have the function of detecting the axial position of the traction shaft and allowing the starting of the electrospindle only if the shaft is in the correct position.

However, the insertion of the signalling devices leads to an increase in the size of the electrospindle at least in the longitudinal direction, often being excessive and not suitable for the specific use.

Presentation of the invention

The object of the present invention is to provide an electrospindle which allows to overcome at least partially the drawbacks described above.

In particular, an object of the present invention is to provide an electrospindle equipped with a system for detecting the axial position of the traction shaft.

Another object of the present invention is to provide an electrospindle which, although comprising the aforementioned detection system, keeps at least the longitudinal dimensions substantially unchanged.

Said objects, as well as others which will become clearer below, are achieved by an electrospindle according to the following claims, which are to be considered as an integral part of this patent.

In particular, the electrospindle comprises a motor for moving a tool and a traction shaft operatively coupled to the motor. This shaft has a first end configured to receive and hold the tool typically, but not necessarily, by means of a gripper.

The traction shaft is movable both in a rotational sense and according to its longitudinal development axis. This latter movement, in particular, is obtained by means of a pneumatic circuit.

In this way, the traction shaft can be arranged according to a first recessed work configuration, in which the tool is retained and can therefore be moved safely, or in a second rest configuration in which the movement of the tool is denied and the traction shaft is at least partially extracted. In this configuration it is in fact possible to remove and replace the tool since the gripper is free to open at least partially.

According to an aspect of the invention, the electrospindle also comprises a joint firmly coupled to the second end of the traction shaft and provided with a fitting for connection to a water delivery pipe. The latter is used by the electrospindle for the machining operations to which it is dedicated.

According to another aspect of the invention, the joint comprises a cover body operatively coupled to the traction shaft by means of rotatable means so as to prevent its rotation and allow its translation with the aforesaid shaft according to the aforementioned longitudinal development axis.

According to a further aspect of the invention, the electrospindle further comprises a signalling element associated with the cover body of the joint. Proximity sensors coupled to the electrospindle are then included to detect the position of the signalling element.

Advantageously, the signalling element and the proximity sensors allow the axial position of the traction shaft to be detected by determining whether it is arranged in the first work configuration or in the second rest configuration.

Still advantageously, in this way it is possible to allow the starting of the electrospindle only if the shaft is in the correct position, i.e. in the working configuration.

Since the signalling element is, in fact, an integral part of the joint, advantageously this solution does not involve an increase in the size of the electrospindle at least in the longitudinal direction.

Brief description of the drawings

Further features and advantages of the invention will be more evident in light of the detailed description of some of the preferred but not exclusive embodiments of an electrospindle according to the invention, illustrated by way of non-limiting example with the aid of the accompanying drawing tables, wherein:

FIG. 1 represents an electrospindle according to the invention, in a partially sectioned side view;

FIGS. 2 and 3 represent details of the electrospindle of FIG. 1.

Detailed description of some preferred exemplary embodiments With reference to the mentioned figures, and in particular to fig. 1 , described herein is an electrospindle 1 commonly used for machining operations such as cutting, milling, drilling or other.

It comprises a motor 2 for moving a tool, not shown in the figures, and a traction shaft 3, which can be seen in fig. 2, for the transmission of motion from the motor 2 to the tool.

The figures show an electrospindle 1 suitable for receiving only an axial machining tool. However, this configuration is not to be considered as limiting for different embodiments of the invention according to which the electrospindle also comprises radial machining tools.

The traction shaft 3 has a first end 4 configured to retainthe aforementioned toolby means of a grippers.

According to the described embodiment, the electrospindle 1 comprises a pneumatic circuit, not shown in the figures, whose function is to move the traction shaft 3 according to its longitudinal development axis X. In particular, the pneumatic circuit takes care of arranging the traction shaft 3 according to a first work configuration or according to a second rest configuration. In the first the tool is retained and can therefore be moved safely, while in the second the movement of the tool is denied since the traction shaft 3 is at least partially extracted. In this latter configuration, consequently, it is possible to safely remove and replace the tool with the gripper 5 free to open at least partially.

The electrospindle 1 further comprises, as can also be seen in fig. 3, a joint 6 coupled to the second end 7 of the traction shaft 3 and provided with a fitting 8 for connection to a water delivery pipe. As mentioned, this is supplied to the electrospindle 1 for the machining operations to be performed.

Since the traction shaft 3 is rotatable, the coupling between it and the joint 6 is ensured by rotatable means 10. Advantageously, they allow the transmission of the rotational motion from the traction shaft 3 to the joint 6 to be prevented, but at the same time allow their translation according to the aforementioned longitudinal development axis X.

According to the embodiment of the invention being described, the rotatable means 10 comprise spheres 12 inserted in respective cavities 13 interposed between the traction shaft 3 and the joint 6. In particular, in the figures it can be seen that the cavities 13 are partially formed on the traction shaft 3 and partially on the internal surface of the joint 6.

Obviously, this aspect should not be considered as limiting for different embodiments of the invention, where, for example, the spheres are inserted in cavities present only in the traction shaft or, according to other embodiment variants, only on the internal surface of the joint.

Also the embodiment of the rotatable means is a feature which should not be construed as a limitation for the present invention. In fact, according to further different embodiments, they can be constituted by bearings of any type or other.

According to an aspect of the invention, the joint 6 comprises a cover body

20 which, thanks to the presence of the rotatable means 10, does not rotate with the traction shaft 3, but moves axially with it.

Conveniently, therefore, the joint 6 also comprises a signalling element 21 integral with the cover body 20. Moreover, the joint 6 comprises a plurality of proximity sensors 22 of the signalling element 21 to determine its position.

Advantageously, since the cover body 20 (and therefore the signalling element 21) moves axially with the traction shaft 3, the proximity sensors 22 allow determining whether this shaft 3 is in the first work configuration or in the second rest configuration.

Still advantageously, it is therefore possible to inhibit the operation of the electrospindle 1 when the tool is not correctly retained preserving the safety of the users who use it.

All this takes place, still advantageously, without modifying the axial dimensions of the electrospindle 1 since the signalling element 21 and the proximity sensors 22 are integrated in the joint 6.

From what has been said, it is clear that the number of signalling elements

21 as well as the number of proximity sensors 22 are not limiting features for the present invention as they can be in any of the two cases according to the multiple functions to be implemented. For example, according to a particular embodiment variant not shown in the figures, there are two signalling elements for accurately determining not only the work configuration, but also the maximum extraction configuration of the gripper. In this case it is clear that the number of proximity sensors also varies accordingly.

As regards the embodiment of the signalling element 21 , according to the embodiment of the invention which is being described, it consists of a shaped body 25 coupled stably on the cover body 20. More in detail, this is a ring having a T-shaped section. The head of the T advantageously allows a better centering of the signalling element 21 , while its base ensures a precise detection.

However, also in this case, the feature which was just described must not be considered as limiting for the present invention. For example, according to some embodiment variants, also not shown here, the signalling element is constituted by a tang formed on the external surface of the cover body.

With respect to the proximity sensors 22, they are preferably, but not necessarily, constituted by inductive sensors. Obviously, also this feature should not be considered as a limiting for the invention.

In light of the foregoing, it is understood that the electrospindle of the invention achieves all the intended purposes.

In particular, an electrospindle equipped with a system for detecting the axial position of the traction shaft has been made available.

On closer inspection, however, all this takes place by keeping the longitudinal dimensions of the electrospindle unchanged.

The invention might be subject to many changes and variants, which are all included in the appended claims. Moreover, all the details may furthermore be replaced by other technically equivalent elements, and the materials may be different depending on the needs, without departing from the protection scope of the invention defined by the appended claims.

Claims

C L A I M S

1. An electrospindle comprising:

a motor (2) for moving a tool;

a traction shaft (3) operatively coupled to said motor (2) to be rotated and having a first end (4) configured to receive and hold the tool;

a pneumatic circuit for translating said traction shaft (3) according to its longitudinal development axis (X) so as to arrange it according to a first work configuration, wherein the movement of the tool is allowed, and a second rest configuration wherein the movement of the tool is denied and its replacement is allowed;

a joint (6) stably coupled to a second end (7) of said traction shaft (3) and provided with a fitting (8) for connection to a water delivery pipe in said electrospindle (1),

characterized in that said joint (6) comprises:

at least one cover body (20) operatively coupled to said traction shaft (3) by means of rotatable means (10) so as to prevent its rotation with said traction shaft (3) and allow its translation with said traction shaft (3) according to said longitudinal development axis (X);

at least one signalling element (21) coupled to said cover body (20); one or more proximity sensors (22) of said signalling element (21) to determine if said traction shaft (3) is in said first work configuration or in said second rest configuration.

2. Electrospindle according to claim 1 , characterized in that said signalling element (21) is a shaped body (25) stably coupled on said cover body

(20).

3. Electrospindle according to claim 2, characterized in that said shaped body (25) is a ring.

4. Electrospindle according to claim 1 , characterized in that said signalling element comprises a tang protruding from said cover body.

5. Electrospindle according to any one of the preceding claims, characterized in that said rotatable means comprise bearings interposed between said traction shaft and said joint.

6. Electrospindle according to any of the claims from 1 to 4, characterized in that said rotatable means (10) comprise spheres (12) inserted in respective cavities (13) interposed between said traction shaft (23) and said joint (6).

7. Electrospindle according to claim 6, characterized in that said cavities (13) are defined by notches made on said traction shaft (3) and on the inner surface of said joint (6).

8. Electrospindle according to any one of the preceding claims, characterized in that said proximity sensors (22) are constituted by inductive sensors.