EP3856458A1

EP3856458A1 - Operating head with electro spindles

Info

Publication number: EP3856458A1
Application number: EP19787480.3A
Authority: EP
Inventors: Giovanni Tupini; Rosario LO PICCOLO
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-09-24
Filing date: 2019-09-23
Publication date: 2021-08-04
Anticipated expiration: 2039-09-23
Also published as: WO2020065689A1; EP3856458B1

Abstract

An operating head with electro spindles comprises a central structure (10) rotating orthogonally to a work plane, able to support a plurality of electro spindles distributed on a circumference with the same angular distance, the axis of rotation of each electro spindle disposed radially with respect to the axis of rotation of the central structure (10). The central structure (10) comprises a substantially polygonal prismatic turret provided on each side face of a flanged seat (11) adapted to receive and support a cylindrical casing (12) of each electro spindle.

Description

OPERATING HEAD WITH ELECTRO SPINDLES

The present invention relates to an operating head with electro spindles.

In general, the present invention refers to machines and devices designed for smoothing and polishing surfaces of inorganic material, for example, stone, ceramic, porcelain, glass.

In particular, the present invention relates to operating heads to work on flat surfaces provided with oscillating abrasive blocks or rotary tool holding spindles connected to synchronous motors with permanent magnets, balancing mechanisms.

The state of the art is represented by patent application DE 4 209 273 A1 concerning a grinding head connected to a machine by a flange with central hole and bearings for a driven vertical spindle. Fixed to the bottom end of the spindle by resiliently bushed screws is housing in the form of an inverted bell with radial extensions. The housing seals on a spherical thrust surface and can move slightly about a pivot point on the spindle centreline. In the radial extensions are horizontal shafts which drive grinding rolls having an elastically backed outer layer of abrasive. The horizontal shafts are driven from the spindle via internal ring gear, spur gear keyed to the spindle, spur gear rotatable on the spindle, bevel gear rotatable on and flexibly mounted on the spindle, and bevel gears on the shafts. The grinding tools therefore have a motion consisting of rotation about their own areas and rotation bodily about the central axis.

Furthermore, the state of the art is represented by US patent 8,534,274 B2 regarding a method and a plant provided for calibrating surfaces of stone materials, suitable for working at least one slab composed of an entry side and an exit side and of two parallel side edges; the slab is pushed along the side edges through a conveyor belt and is subjected to the cutting action imparted by multiple tools equipped with a peripheral speed compatible with optimum cutting parameters for the stone material; the tools move along a predefined path along the surface of the slab, and the motion imparted by the conveyor belt and the predefined tool path is combined in order to completely cover the surface of the slab; the contact between the slab and the tools is ensured simultaneously at least in one point on each of the two side edges of the slab.

It is known the patent EP 1 536 916 B1 concerning spindle comprising a tubular housing in which the spindle body is movable, the spindle body including a shaft carrying a rotary abrasive tool head, and a cylinder for setting the position of the spindle on the metal structure. The body of the mandrel is coaxial with a cylindrical actuator having the piston rod of the hydraulic or pneumatic cylinder coinciding with the body of the spindle allowing a more compact design, a construction more reliable, maintenance more convenient and eliminating any projection of the spindle body.

Moreover, it is known the patent application EP 2 234 213 A1 concerning a joint for transmitting and distributing electric and electronic power coupled with the transmission and distribution of hydraulic and pneumatic power, suitable for connecting two relatively-moving parts, belonging to a machine for working stone materials, wood or glass, comprising a rotary part with respect to a fixed part: the rotary part comprises a hollow cylinder for supporting apparatuses for transmitting and distributing electric power, electric signals, pneumatic power, hydraulic power.

During the grinding operation, a grinding head develops vibrations and shocks which can damage the material to be treated. If the pressure on the surface to be polished is distributed as uniformly as possible it is possible to distribute the consumption of the grinding elements. The invention of patent application DE 4 209 273 A1 operates in this way. However, a mechanical transmission such as that of patent application DE 4 209 273 A1 partially solves the problem of the transmission of shocks and vibrations isolating the single grinding element from the respective gear but maintaining the flow of the noise intact in the area of the inner ring gear. Therefore, a positive effect of a distribution of the noise source does not correspond to a decrease of the noise. At the level of the internal ring gear, continuous shocks and vibrations circulate with the risk of triggering the resonance of the gear train involved.

A hint to solve the technical problem of the invention is given by patent US 8,534,274 B2 by means of a train of tool-holding spindles connected to a respective coaxial electric motor which operates independently from the other motors of the other shafts. In this way, without inner crown like that of the patent DE 4 209 273 A1 the disturbance of shocks and vibrations can not be transmitted to the train of spindles.

The patent US 8,534,274 B2 relates to a big head that is not suitable for the rectification of a slab, while it is preferred a head of contained dimensions capable of elastically adapt to the development of the slab. Traditionally, a rigid structure ensures uniform thickness of a thick slab. But in the case of thin and flexible slab becomes important to be able to follow the concave or convex shape of the surface of the slab, in order to avoid an overworking of edges and corners. This problem is solved by an operating head provided with a train of electric spindles of contained radial dimension. Permanent magnet motors capable of delivering energy with a high power magnetic density collected in a resized volume can solve the problem.

Moreover, an operating head with a train of electric spindles is equipped with a joint for the transmission and distribution of electrical energy, of the type described in the patent EP 2 234 213 A1.

Moreover, high efficiency of grinding of the slab is obtained by using an operating head with electrical spindles equipped with a device capable to neutralize the effect of the mass. A fluid-dynamic cylinder to set the position of the spindle of an operating head is connected to the operating head, of the type described in the patent EP 1 536 916 B1.

An advantage of the present invention is that of having an operating head with a plurality of drive spindles of reduced volume and at the same time with a high power of abrasion. A further advantage is that of being able to provide a working head of reduced overall dimensions and high mechanical performance.

The aforementioned and other objects and advantages of the invention, as they will emerge from the following description, are achieved with an operating head with electro spindles, as described in the main claim. Preferred embodiments and non-trivial variants of the present invention form the object of the dependent claims. It is understood that all the deriving claims form an integral part of the present description. It will be immediately obvious that innumerable variations and modifications (for example relating to shape, dimensions, arrangements and parts with equivalent functionality) can be made to the description without departing from the scope of protection of the invention as it appears from the appended claims..

The present invention will be better described by some preferred embodiments thereof, given as a non-limiting example, with reference to the enclosed drawings, in which:

FIG. 1 shows a perspective view of an embodiment of the operating head with electro spindles according to the present invention;

FIG. 2 shows the previous figure without the upper part of the operating head with electro spindles; and

FIG. 3 shows a section along the vertical plane passing through the axis of rotation of the previous figure.

With reference to the figures, it is possible to note that an operating head with electro spindles comprises a central structure 10 rotating orthogonally to a work plane. The central structure 10 is able to support a plurality of electro spindles distributed on a circumference with the same angular distance, the axis of rotation of each electro spindle disposed radially with respect to the axis of rotation of the central structure.

Advantageously, the central structure 10 comprises a substantially polygonal prismatic turret provided on each side face of a flanged seat 11 adapted to receive and support a cylindrical casing 12 of each electro spindle.

In particular, the rotor and the stator of each electro spindle belongs to a synchronous motor with permanent magnets, the permanent magnets mounted on the rotor surface or inserted inside the rotor, the stator installed around the rotor with a space between the rotor and the stator, the coils wound around the stator, so that when the electric current is applied to the coil, the rotor is rotated by a force applied in a certain direction.

The central structure 10 allows housing inside of it a plurality of wirings for the transmission and distribution of electrical and electronic power.

According to a preferred configuration, the operating head with electro spindles comprises at least one pneumatic device 20 of vertical approach connected to the central structure 10 to balance a certain overall mass and maintain the operating head with electro spindles in a floating condition.

Examples

An operating head with electro spindles, object of the present invention, is adapted to replace an operating head according to the state of the art. For example, a known multi-spindle calibrating head, comprising twenty electro spindles uniformly distributed on a circumference with a diameter equal to 1600 mm, in radial direction, each electro spindle of 1,7 kW, could be replaced with an operating head with electro spindles, of the type according to the present invention, comprising six electro-spindles uniformly distributed on a circumference of diameter equal to 670 mm, in radial direction, each electro-spindle of about 6.0 kW, the overall dimensions of the 6 kW electro spindle being the same as the electro-spindle of 1,7 Kw, thanks to a downsizing, through the adoption of permanent magnet technology, with the same operating force and speed of the rotating shaft.

An operating head with six electric spindles arranged on a circumference with a diameter of 660 mm is suitable for working a slab of stone material moving on the curved surface of the slab. Therefore the electro spindle resizing allows adjusting the orientation of the calibrating head to the curvature of the slab to be processed. This aspect becomes important for slabs coming from traditional sawing, with wire and blades, compared to those coming from diamond sawing, more precise and flat but limited to small slabs, and in particular for slabs of agglomerated material.

In order to be able to ensure homogeneous processing, the number of six motors constitutes in practice an optimum value for a covering of the working points.

The diamond wheels used with greater frequency are those with a diameter around 200 mm.

An operating head with electrical spindles according to the present invention is suitable for compensating for a mass by means of a feedback device with a pneumatic cylinder controlled by a pressure regulator.

A spindle with permanent magnets supplied by an inverter of 400 V, three phases, may have the following characteristics: nominal speed 3000 rpm; frequency, 250 Hz; 10 poles; maximum speed 4000 rpm; nominal torque, 16 Nm; maximum torque 30 Nm; current maximum torque 44, A; size 130X190X190; mass, 3, 5 kg; type of service, 51.

Claims

Operating head with electro spindles, comprising a central structure (10) rotating orthogonally to a work plane, said central structure (10) able to support a plurality of electro spindles distributed on a circumference with the same angular distance, the axis of rotation of each electro spindle disposed radially with respect to the axis of rotation of the central structure (10), characterized in that the central structure (10) comprises a substantially polygonal prismatic turret provided on each side face of a flanged seat (11) adapted to receive and support a cylindrical casing (12) of each electro spindle.
Operating head with electro spindles according to the previous claim, characterized in that the rotor and the stator of each electro spindle belongs to a synchronous motor with permanent magnets, the permanent magnets mounted on the rotor surface or inserted inside the rotor, the stator installed around the rotor with a space between the rotor and the stator, the coils wound around the stator, so that when the electric current is applied to the coil, the rotor is rotated by a force applied in a certain direction.
Operating head with electro spindles according to one of the preceding claims, characterized in that the central structure (10) allows housing inside of it a plurality of wirings for the transmission and distribution of electrical and electronic power.
Operating head with electro spindles according to one of the preceding claims, characterized in that it comprises at least one pneumatic device (20) of vertical approach connected to the central structure (10) to balance a certain overall mass and maintain the operating head with electro spindles in a floating condition.