PT101657B

PT101657B - WIRE TRACTION MECHANISM FOR ELECTROEROXY MACHINE

Info

Publication number: PT101657B
Application number: PT101657A
Authority: PT
Inventors: Jose Maria Onandia Albizuri
Original assignee: Ona Electro Erosion
Priority date: 1994-02-15
Filing date: 1995-02-13
Publication date: 1997-02-28
Also published as: GB9501918D0; GB2286355A; FR2716127B1; IT1275218B; GB2286355B; ITMI950210A1; FR2716127A1; ITMI950210A0; CH690493A5; PT101657A

Abstract

In electroerosion machines, the main wire-traction device is located in a lower head (4) arranged under the immediate area of the workpiece (5) and consists of a traction wheel (7), a first free wheel (81) and a second free wheel (82), each joined to a pivoting arm (131, 132), which arms are arranged 90 DEG apart with respect to the traction wheel (7), the first and second free wheels being pressed against the traction wheel under the effect of a first and a second spring (151, 152). Preferably the pressure on the second free wheel (82) is greater than on the first. A guide chute (16) is provided between the free wheels. <IMAGE>

Description

Nas máquinas de electroerosão por fio podem-se produzir numerosas roturas do fio, o que origina problemas tecnico-económicos de manutenção, reparações e amortizações relacionados com os tempos de paragem da máquina.In wire EDM machines, numerous wire breakages can occur, which leads to technical and economic maintenance, repairs and depreciation problems related to the machine downtime.

O requerente observou que para evitar vibrações indesejáveis que podem originar um aumento das roturas do fio e um trabalho defeituoso sobre a peça a trabalhar, é necessário colocar a cabeça inferior com o dispositivo de tracção principal o mais perto possível da peça a trabalhar e de preferência situada imediatamente por debaixo da mesma.The applicant noted that in order to avoid undesirable vibrations that can lead to an increase in wire breaks and defective work on the workpiece, it is necessary to place the lower head with the main traction device as close as possible to the workpiece and preferably located immediately below it.

O presente invento preconiza um mecanismo de tracção do fio para a máquina de electroerosão que se caracteriza por colocar uma cabeça inferior sob a vizinhança da peça a trabalhar e que consta de uma roda de tracção, de uma primeira roda louca e de uma segunda roda louca, unidas cada uma a braços articulados que se dispõem entre si segundo um ângulo de 90° em relação à roda de tracção e em que a primeira e segunda rodas loucas encontram-se pressionadas contra a roda de tracção sob a acção de uma primeira e segunda mola.The present invention provides for a wire traction mechanism for the EDM machine which is characterized by placing a lower head under the vicinity of the workpiece and which consists of a traction wheel, a first crazy wheel and a second crazy wheel , each connected to articulated arms that are arranged at an angle of 90 ° with respect to the traction wheel and in which the first and second crazy wheels are pressed against the traction wheel under the action of a first and second spring.

Ao mesmo tempo, melhorou-se o contacto eléctrico entre a tomada de corrente e o fio.At the same time, the electrical contact between the socket and the wire has been improved.

-20 invento também se caracteriza por na cabeça inferior se localizarem, pelo menos, quatro terminais, em correspondência com os cabos coaxiais de transmissão da corrente eléctrica pulsada, estando cada terminal ligado electricamente ao corpo da referida cabeça inferior e sobre o qual dispõe-se frontalmente sobre uma das suas bases uma tomada de material condutor, em forma de prisma de secção poligonal e de faces convexas, girável sobre o seu eixo, e invertível, apoiando-se o fio sobre uma das faces em forma de arco.-20 invention is also characterized by the fact that at least four terminals are located on the lower head, in correspondence with the coaxial cables for the transmission of the pulsed electric current, each terminal being electrically connected to the body of said lower head and on which it is located frontally on one of its bases a socket of conductive material, in the form of a polygonal section and with convex faces, rotatable on its axis, and invertible, resting the wire on one of the faces in the shape of an arc.

A figura 1 é uma vista em corte de um modo de realização do objecto do invento.Figure 1 is a sectional view of an embodiment of the object of the invention.

A figura 2 é uma vista do dispositivo da figura 1, na união do mesmo à máquina de electroerosão.Figure 2 is a view of the device of figure 1, in connection with the device of the EDM machine.

A tomada (6), de preferência de carboneto de tungsténio (widia), tem a forma de um prisma de secção poligonal de faces (18) convexas.The socket (6), preferably of tungsten carbide (widia), is in the form of a polygonal section prism with convex faces (18).

O contacto entre o corpo condutor (19) da cabeça (4) e a tomada (6) é frontal, quer dizer, a base da tomada (6) assenta contra o corpo (19).The contact between the conductive body (19) of the head (4) and the socket (6) is frontal, that is, the base of the socket (6) rests against the body (19).

O fio (1) não é tangente à face de contacto (18), abraçando-a em vez disso, pelo que a zona de contacto em vez de ser pontual é linear (arco de contacto), melhorando assim o contacto eléctrico.The wire (1) is not tangent to the contact face (18), embracing it instead, so the contact area instead of being punctual is linear (contact arc), thus improving electrical contact.

-3 Para conseguir o referido efeito, a face de contacto (18) corta a direcção do fio (1) que vai desde a guia superior (20) até à zona principal de arrasto.-3 To achieve this effect, the contact face (18) cuts the direction of the wire (1) that goes from the upper guide (20) to the main drag area.

A tomada (6) é rotativa, pelo que cada uma das suas faces se apresenta como face de contacto, podendo dar meia volta e apresentar a sua outra base como contacto com o corpo (19) e a outra zona da face (18) para o contacto com o fio (1).The socket (6) is rotatable, so that each of its faces presents itself as a contact face, being able to turn and present its other base as contact with the body (19) and the other area of the face (18) for contact with the wire (1).

O fio (1) que vem da cabeça superior (não representada) passa pela peça de trabalho (5) e chega à cabeça inferior (4) colocada inferiormente na vizinhança da referida peça de trabalho (5).The wire (1) that comes from the upper head (not shown) passes through the workpiece (5) and reaches the lower head (4) placed inferiorly in the vicinity of the said workpiece (5).

O fio (1) depois de passar pela correspondente boca (3) de refrigeração, entra em contacto com o toma-corrente (6).The wire (1) after passing through the corresponding cooling mouth (3), comes into contact with the socket (6).

A corrente eléctrica transmite-se, para evitar quedas do pico de intensidade, por meio de cinco cabos coaxiais, cujos fios interligam-se entre a peça (5) e os terminais (17) da cabeça inferior (4) e os correspondentes à cabeça superior que tem também a sua tomada correspondente.The electric current is transmitted, to prevent falls from the peak intensity, through five coaxial cables, whose wires interconnect between the part (5) and the terminals (17) of the lower head (4) and those corresponding to the head which also has its corresponding socket.

De seguida, o fio (1) entra na zona principal de arrasto que consta de uma roda de arrasto (7) e de duas rodas loucas (8j) e (82) dispostas de preferência entre si segundo um ângulo de 90°, em relação à roda de arrasto (7).Then, the wire (1) enters the main drag zone consisting of a drag wheel (7) and two crazy wheels (8j) and (82) preferably arranged at an angle of 90 ° with respect to each other. the drag wheel (7).

-4A roda de arrasto (7) será de preferência de material cerâmico e recebe o respectivo binário por meio de uma correia de transmissão accionada por um motor (10).-4 The trailing wheel (7) is preferably made of ceramic material and receives its torque through a transmission belt driven by a motor (10).

A cabeça inferior (4) une-se à bancada (11) da máquina por meio de um braço (12) portador da correia (9) de tr ansmissão.The lower head (4) is connected to the bench (11) of the machine by means of an arm (12) carrying the transmission belt (9).

As rodas loucas (81) e (82), por meio dos braços (131) e (132), articulam-se nos eixos (141) e (142) contra a acção das molas (151) e (152) respectivamente, pelo que pressionam 0 fio (1) entre elas e a roda de arrasto (7) ou de tracção.The crazy wheels (81) and (82), by means of the arms (131) and (132), articulate on the axles (141) and (142) against the action of the springs (151) and (152) respectively, by pressing the wire (1) between them and the drag wheel (7) or traction.

A superfície da primeira roda louca (81) é de preferência de natureza elástica, a superfície da segunda roda louca (82) é de natureza cerâmica e a da roda de arrasto (7) é também de natureza cerâmica, embora possam ser de outras naturezas conhecidas.The surface of the first crazy wheel (81) is preferably of an elastic nature, the surface of the second crazy wheel (82) is of a ceramic nature and that of the drag wheel (7) is also of a ceramic nature, although they may be of other nature known.

Está previsto que a força exercida pela mola (152) sobre a segunda roda louca (82) seja superior à exercida pela mola (151) da primeira roda louca (81), para evitar que 0 fio (1) se separe da roda de tracção (7), melhorando-se deste modo a condução.The force exerted by the spring (152) on the second idler wheel (82) is expected to be greater than that exerted by the spring (151) of the first idler wheel (81), to prevent the wire (1) from separating from the drive wheel (7), thereby improving driving.

Entre ambas as rodas loucas (81) e (82) existe uma guia inclinada helicoidal (16) para 0 fio (1).Between both the idler wheels (81) and (82) there is a helical inclined guide (16) for the wire (1).

Claims

I ^a .- Wire traction mechanism for an EDM machine, characterized in that the main wire traction device is located on a lower head located under the vicinity of the work piece and which comprises a traction wheel, a first crazy wheel and a second crazy wheel, each connected to articulated arms, which are arranged at an angle of 90 ° with respect to the traction wheel, the first and second crazy wheels being pressed against the traction wheel under the action of a first and second second spring.

2 ^a .- Wire pulling mechanism for an EDM machine, according to the previous claim, characterized in that the first crazy wheel has its surface in elastomeric material.

3 ^a .- Wire pulling mechanism for an EDM machine according to claim 1, characterized in that the second spring that presses the second crazy wheel exerts greater pressure than the first spring on the first wheel.

4 ^a .- Wire pulling mechanism for an EDM machine according to claim 1, characterized in that between the first and the second crazy wheel there is an inclined helical guide for the wire.

5 ^a .- Wire pulling mechanism for an EDM machine according to claim 1, characterized in that the head

-2 lower there are at least four terminals, in correspondence with the coaxial cables for transmitting the pulsed electric current, each terminal being electrically connected to the body of said lower head and on which a front socket is disposed on one of its bases conductive material, in the shape of a polygonal section prism and with convex faces, rotatable on its axis, and invertible, the wire resting on one of the faces in the shape of an arc.

6 ^a .- Wire traction mechanism for an EDM machine, according to claim 1, characterized by having a motor that transmits the respective torque to the traction wheel by means supported by a head connecting arm lower than the machine structure.