Description:‘A SYSTEM AND A METHOD FOR DEMAGNETISING AN ELECTROMAGNETIC CLUTCH ASSEMBLY IN MACHINE TOOLS’

FIELD OF INVENTION
[001] The present invention in general relates to a demagnetizing device for an electromagnetic clutch assembly and a method thereof. The device of the invention demagnetizes the coil of the clutch, clutch plates, yoke and shaft, thereby reducing the short circuit of the coil and preventing the electromagnetic clutch from abnormal damage and malfunction.

BACKGROUND OF THE INVENTION

[002] Background description includes information that may be useful in understanding the present invention.

[003] Electromagnetic clutches, also referred to as ‘electromechanical’ or ‘E.M.’ clutches, actuate electrically but transmit torque mechanically. The basic design of an E.M. clutch consists of an electromagnetic coil within a metal housing (stator), a rotor connecting to the input source, and an armature that connects to the output source. To engage an E.M. clutch, the coil is energized creating a magnetic field which pulls the armature friction plate to the rotor friction plate, establishing a frictional mechanical connection. The force between the friction surfaces transmits torque from the input rotor to the output armature. A variation to the friction disc design is a toothed design for timing / position control and for higher torque applications.

[004] To disengage the E.M. clutch, the electrical power source is shut off. With no magnetic field present, the armature is pulled back into its default position by a recessed flat spring. This action creates a small air gap between rotor and armature plates, effectively disengaging the output armature and ceasing torque transmission.

[005] Over the years of usage of E.M. clutch, it may get magnetized even without applying electrical power. After that demagnetization of the clutch assembly is required to be carried out.

[006] The demagnetization or removal of a magnetic field may be accomplished in several ways. One demagnetization approach is to heat a material above its Curie temperature to produce a random orientation of the magnetic domains, which demagnetizes the material. Another demagnetization approach is to subject the material to a reversing and decreasing magnetic field produced by driving a (de)magnetizer with a decreasing alternating current. An alternative demagnetization approach is the subject of the present invention.

[007] Thus, there exists a need for specifically designed single wire electromagnetic clutches to be used in machine tools.

PRIOR ART OF THE INVENTION

[008] Patent no. EP1098111A2 discloses an apparatus and method for demagnetizing a differential (212) which has a controllable electromagnetically actuated clutch (101). The apparatus includes sensors and a coil (220) connected to a control module. The sensors receive vehicle inputs to indicate various measured values such as vehicle speed, brake pressure, magnetization current provided to the differential (212), and the like and generates signals which are transmitted to the control module. The control module initiates a demagnetization cycle when certain conditions have been satisfied as indicated by the input signals. The control module provides a DC voltage to the coil (220) to generate magnetic flux for demagnetizing the differential (212) and the components of the differential. In one embodiment a single coil is provided to which is applied both magnetization and demagnetization current. In another embodiment two coils (218, 220) are provided, one (218) for generating magnetization flux and the other (220) for generating demagnetization flux. The control alternatively applies voltages of reverse polarity in decreasing amplitudes for predetermined periods of time during a demagnetization cycle.

[009] Publication no. WO2003072970A1 discloses a controller of an electromagnetic clutch (70) performing a switching operation between coupling and uncoupling of a power transmission mechanism in order to transmit or not transmit power between an engine and a dynamo-electric machine through the power transmission mechanism thus preventing generation of a loud impact sound from the electromagnetic clutch. At the time of making a switch from coupled state to uncoupled state, excitation damping means (120, 130) reduce exciting power gradually while switching the exciting direction of the electromagnetic clutch (70) by a field coil (71) alternately.

OBJECTS OF THE INVENTION

[0010] It is an object of the invention to provide a demagnetizing device for an electromagnetic clutch assembly.

[0011] It is an object of the invention to provide a method of demagnetization for an electromagnetic clutch assembly.

[0012] Yet another object of the invention is to provide a demagnetizing method which allows small to very large and heavy objects to be demagnetized on site flexibly and without disassembly reproducible.

[0013] Yet another object of the invention is to provide the demagnetizing device in which longer downtime of equipment in which objects are eliminated with residual magnetism.

[0014] Yet another object of the invention is to provide the demagnetizing device in which objects do not necessarily to be moved away for demagnetization.

[0015] Yet another object of the invention is to provide the demagnetizing method that does not require transportation of the objects with residual magnetism through transport roads or otherwise, which lead to complications before and during demagnetization.

[0016] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.

SUMMARY OF THE INVENTION

[0017] The present invention is relating to a device and method for demagnetization of the electromagnetic clutch assembly in machine tools.

[0018] The present invention is a system for demagnetizing an electromagnetic clutch assembly in machine tools comprises a demagnetization device comprising an intermediate relay connected to an output of a control transformer. A timer controller connected with a coil of the electromagnetic clutch. The timer controller assembled for the detection of a response of the control transformer. The demagnetization device determines the output of the timer controller, and demagnetize the coil of the electromagnetic clutch.

[0019] In an aspect of the invention, the demagnetization device is used in electrical control system to avoid damage of the electromagnetic clutch.

[0020] In an aspect of the invention, the control transformer is an AC transformer.

[0021] In an aspect of the invention, a primary winding of the control transformer is operable to provide 300 VA of output.

[0022] In an aspect of the invention, the primary winding of the control transformer connected to 230 V AC mains.

[0023] In an aspect of the invention, a DC clutch is connected to the secondary side of the control transformer .

[0024] In an aspect of the invention, in the demagnetization device, a pulsed magnetizer and at least one magnetizing coil is assembled that receives a sequence of discrete currents from the pulsed magnetizer and outputs a sequence of discrete magnetizing fields to overwrite and at least partly demagnetize the region of a magnetic structure.

[0025] In an aspect of the invention, demagnetizing the coil reduces the short circuit of the coil and prevents the electromagnetic clutch from abnormal damage.

[0026] In an aspect of the invention, the load is balanced and in the range of about 10W.

[0027] In an aspect of the invention, the demagnetization device is a portable unit and comprises an ON button for demagnetizing action.

[0028] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0029] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:

[0030] FIG 1A. shows a system with plurality of modules for demagnetization according to the present invention ; and

[0031] FIG 1B. shows a control circuit for a demagnetizing device according to the present invention.

[0032] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

[0033] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.

[0034] In the present disclosure, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0035] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the present disclosure to the particular forms disclosed, but on the contrary, the present disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the present disclosure.

[0036] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

[0037] In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0038] The present invention relates to a system (100) and method for demagnetization of the electromagnetic clutch assembly in machine tools. The system (100) used for demagnetizing a region of a magnetic structure. The system (100) comprises a pulsed magnetizer (02) and at least one magnetizing coil (04). The at least one magnetizing coil (04) receives a sequence of discrete currents from the pulsed magnetizer (02) and outputs a sequence of discrete magnetizing fields to overwrite and at least partly demagnetize the region of the magnetic structure. In a preferred embodiment a magnetic clutch discharge degaussing gear comprises magnetic clutch and control unit.

[0039] FIG 1A. shows the system (100) with plurality of modules for demagnetization according to the present invention. A demagnetizing device (22) (as shown in FIG.1B) comprises an electromagnetic clutch (12) and a control transformer (20). A plurality of modules such as 24V DC clutch (06 ), a clutch body (08), a single wire electromagnetic clutch (12 ), earth (14 ), a load (16 ) is connected with the control transformer (20) and a timer controller (18). The single wire electromagnetic clutch (12 ) is connected to the earth (14 ). The timer controller (18) having a setting of >>ON time (2sec) and << OFF time (3sec). The 24V DC clutch (06) acts as an electromagnetic clutch during the operation. The control transformer (20) primary winding is connected to the ph and N with receiving input of 230V. The secondary of the control transformer (20) is connected to an intermediate relay (10) with the voltage of range (0, 24). The load (16) is balanced one and is the range of 10W. A primary winding of the control transformer (20) is connected to 230 V AC mains. In the control transformer (20) primary winding is operable to provide 300 VA of output. In a preferred embodiment the demagnetizing device (22) operates on electromagnetic clutch in which the device demagnetizing unit comprises of a portable unit with an ON button for demagnetizing action.

[0040] FIG 1B. shows a control circuit for a demagnetizing device (22). In one embodiment in the demagnetizing device (22), the intermediate relay (24) is connected to the output of the 415/24 V AC transformer (20). An auxiliary normal open contact of the timer controller (18) is connected with the coil of the electromagnetic clutch (12). The device (22) demagnetize the coil of the clutch (06), thus reducing the short circuit of the coil and preventing the electromagnetic clutch from abnormal damage.

[0041] In one embodiment a method of demagnetization allows small to very large and heavy objects to be demagnetized on site flexibly and without disassembly reproducible. Thus, longer downtime of equipment in which objects are eliminated and residual magnetism is avoidable.

WORKING OF THE INVENTION

A kind of method of implementing electromagnetic clutch discharge degaussing gear the steps include:
In the 1st step, when power supply is provided to the electromagnetic clutch, the adhesive function is activated and the clutch performs its function. When the power supply to the clutch is switched OFF, then clutch open signal is activated and the clutch is opened. If normal, then clutch is opened and the control loop functions properly. If undesired or the clutch is magnetized, then the opening function is not completed and the clutch remains engaged. Then trigger electromagnetic clutch discharge demagnetization loop using the invention.

The clutch demagnetising unit is connected to the single wired clutch as per FIG 1B.
When 230V supply to the unit is activated, the step down transformer gives 24V AC output. The 24V AC output is provided in a pulsed form by using a timer and is applied to the positive terminal of the clutch. The ZERO volt point of the transformer is connected to the clutch through a load. The load shall be varied based on the clutch size and extent of magnetism. When pulsed alternating voltage is to the clutch, the magnetizing and demagnetising cycle is repeated in a loop. The electromagnetic clutch discharge degaussing gear forms discharge demagnetization loop, discharges residual current over the load. This process is continued for approximately 2 minutes so that the residual magnetism is discharged over the load and the clutch is fully demagnetized.

[0042] In a preferred embodiment by means of an alternating voltage, which usually alternates with the mains frequency, an alternating current flow is generated by at least one inductance and thereby an alternating magnetic field in the vicinity of the inductance. The alternating voltage is easily switched on and off by means of a timer controller (18). After switching on, the alternating voltage is applied uncontrolled to the at least one inductor and the corresponding alternating magnetic field is induced until it is switched off. The demagnetization loop, discharges residual current over the load (16).

TECHNICAL ADVANTAGES
[0043] Using the demagnetizing device longer downtime of equipment in which objects are to be eliminated with residual magnetism is avoidable.

[0044] Using the demagnetizing device damage of electromagnetic clutch is prevented.

[0045] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.

[0046] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope. The present invention will now be described more specifically with reference to the following specification.

[0047] Although embodiments for the present subject matter have been described in language specific to package features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/device of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.
, Claims:We Claim:
1. A system (100) for demagnetizing an electromagnetic clutch assembly (12) in machine tools comprises:

a demagnetization device (22), comprising:
an intermediate relay (10) connected to an output of a control transformer (20);
a timer controller (18) connected with a coil of the electromagnetic clutch (12);
wherein
the timer controller (18) assembled for the detection of a response of the control transformer (20); and
the demagnetization device (22) determines the output of the timer controller (18), and demagnetize the coil of the electromagnetic clutch (12).

2. The system as claimed in claim 1, wherein the demagnetization device (22) is used in electrical control system to avoid damage of the electromagnetic clutch (12).

3. The system as claimed in claim 1, wherein the control transformer (20) is an AC transformer.

4. The system as claimed in claim 3, wherein a primary winding of the control transformer (20) is operable to provide 300 VA of output.

5. The system as claimed in claim 3, wherein the primary winding of the control transformer (20) connected to 230 V AC mains.

6. The system as claimed in claim 1, wherein a DC clutch (06) is connected to the secondary side of the control transformer (20).

7. The system as claimed in claim 1, wherein in the demagnetization device (22), a pulsed magnetizer (02) and at least one magnetizing coil (04) is assembled that receives a sequence of discrete currents from the pulsed magnetizer (02) and outputs a sequence of discrete magnetizing fields to overwrite and at least partly demagnetize the region of a magnetic structure.

8. The system as claimed in claim 1, wherein coil demagnetization reduces the short circuit of the coil and prevents the electromagnetic clutch (12) from abnormal damage.

9. The system as claimed in claim 1, wherein the load (16) is balanced and in the range of about 10W.

10. The system as claimed in claim 1, wherein the demagnetization device (22) is a portable unit and comprises an ON button for demagnetizing action.