ES2264891A1 - Impact protection system for electrical discharge machine inlets - Google Patents

Abstract

The invention relates to an impact protection system for the inlets of electrical discharge machines of the type that comprise an upper head (1) having an upper inlet (2), a lower head (3) having a lower inlet (4) and an arm (5) for supporting the lower head (3). The invention is characterised in that the lower head (3) is connected to the support arm (5) by means of first load cells (6) and the upper inlet (2) is connected to the upper head (1) by means of second load cells (7), the signals from said load cells (6, 7) being transmitted to a microprocessor which controls the movements of the electrical discharge machine. The invention is intended for electrical discharge machines.

Description

Shock protection system, for mouths of EDM machines.

In the current state of the art already known EDM machines, and more specifically the machines of  structured wire EDM, for example, according to Spanish patents ES2073346, ES2078292, ES2206101 and ES2107339, among other.

This type of EDM machines by thread, in general, consist of an upper head with a mouth upper and a lower head with a lower mouth between the which mouths the thread passes. The top head is mounted directly on the machine frame and the lower head is mounted on a support arm (indirectly on the frame of the machine).

Both the upper head and the support arm They are areas of the machine that should not withstand shocks.

The object of the invention is a system of crash protection. It is characterized because the union of lower head to the support arm is made by means of first load cells and the attachment of the upper mouth to the head upper is done by means of second load cells sending the load cells their signals to a microprocessor that Controls the movements of the EDM machine.

Particularly:

a) two or more first cells of load at the junction of the lower head to the support arm, which preferably they are angularly equidistant from each other;

b) two or more second cells are arranged load at the junction of the upper mouth to the upper head, which preferably they are angularly equidistant from each other.

With the system object of the invention is achieved protect the machine in a very fast, sensitive and very effective way against shocks or unwanted mechanical stresses, usually caused by programming errors or manual movements careless.

The advantage of this system over others conventionally used for protection of mechanical elements against shocks is remarkable: if in a machine of these characteristics, the protection by limiting the current intensity of the motors that drive the carriages, or of! imitators of the torque transmitted from the motors to the spindles, or of mechanical fuses of preferential breakage in the event of a collision, is reflected in a maximum force value, transmitted to the elements to be protected, of 100 (absolute units), the value The maximum force that reaches these elements in the case that they are protected with load cells, according to the object of this invention, is 5-10. As you can see, the increase in sensitivity in relation to conventional media is
remarkable.

To better understand the purpose of this invention, a preferred form of practical realization, susceptible to accessory changes that do not distort its foundation.

Figure 1 represents a partial view in perspective of the upper (1) / lower (3) head area of a wire EDM machine that incorporates the system of protection against shocks object of the invention.

Figure 2 is a schematic partial view in elevation of the connection between support arm (5) and lower head (3) with interposition of said first load cells (6).

Figure 3 is a schematic partial view in perspective, of the connection between support arm (5) and lower head (3) with interposition of said first load cells (6).

An example of practical, non-limiting embodiment of the present invention.

The object of the invention is a system of crash protection, for machine mouths EDM, particularly for EDM machines thread consisting of an upper head (1) with a mouth upper (2) and a lower head (3) with a lower mouth (4); said upper head (1) being arranged in a frame upper bearing (B) and said lower head (3) in one arm bottom support (5).

In accordance with the invention:

a) at the junction between the lower head (3) and the support arm (5) first load cells are arranged (6), and

b) at the junction between the upper head (1) and The upper mouth (2) has a second load cell (7).

The load cells (6), (7) used are mechanical elements rigid enough to withstand the top (1) and bottom (3) heads of the machine wire EDM without significantly deforming during the usual machine work. Load cells (6), (7) support these heads (1), (3), being the only elements of union between them and the rest of the machine.

These load cells (6), (7) carry built-in sensors very sensitive to the deformation, which originate a much greater electrical signal as larger is the deformation of the load cell element. Any force applied against a head (1), (3) causes a deformation in the load cell (6), (7) that supports it that creates in turn an electrical signal related to this deformation and, therefore, with the force that originates it. As the heads of wire EDM do not support forces in their usual work remarkable or widely variable, this feature is used for, monitoring the electrical signal generated by the cells of load (6), (7), know if any of the heads (1), (3) is forcing or crashing into an obstacle.

When the monitored signal exceeds a value preset, the machine control acts accordingly, taking into account the speed and direction of movement of the heads (1), (3) at the time of mechanical tension or shock, to give the corresponding alarm and stop the machine or reverse the movement quickly, in order to avoid damage to the heads (1), (3) or in the rest of the mechanical structure of the machine, as it is of great precision and must be protected against shocks or tensions

The heads and, in particular, their mouths upper (2) and lower (4), are the most likely points of shock, because they are those that are close to the parts that the machine will cut, with scraps that usually fall on them and that they can hook with fixed elements such as the work table or others The structural support elements of the heads (1), (3) it is very unlikely that they collide. For this reason, the load cells (6), (7) hold only the heads (1), (3) and not all mobile systems of the machine.

On the other hand, it makes no sense to support the mobile structural elements (frame (B) and large arm (5)) with load cells (6), (7), because on the one hand it would be a great economic cost and, on the other hand, it would mean a decrease in the sensitivity of the system, since in this case a small force (the shock force) should be detected between several large forces acting on the corresponding load cell (6), (7) (inertia of the structure
fastened, its weight, etc. ...)

By construction, more than one cell of load (6), (7) at each junction; arranging several load cells (6), (7) both at the junction of the lower head (3) to the arm support (5) as in the union of the head (1) to the upper mouth (2) equidistant angularly from each other and in symmetrical arrangement for Detect any shock according to any direction.

Claims (3)

1. Shock protection system for mouths of EDM machines, consisting of an upper head (1) with an upper mouth (2), a lower head (3) with a lower mouth (4) and an arm support (5) of the lower head (3), characterized in that the union of the lower head (3) to the support arm (5) is carried out by means of first load cells (6) and the union of the upper mouth (2) the upper head (1) is carried out by means of a second load cells (7) sending the load cells (6), (7) their signals to a microprocessor that controls the movements of the machine of
EDM 2. Shock protection system, for mouths of EDM machines, according to previous claim, characterized in that two or more first load cells (6) are arranged at the junction of the lower head (3) to the support arm (5), equidistant angularly with each other. 3. Shock protection system, for mouths of EDM machines, according to claim 1, characterized in that two or more second load cells (7) are arranged at the junction of the upper mouth (2) to the upper head (1), angularly equidistant from each other.