Wire guide apparatus for an electric spark forming machine

A wire guide apparatus for the wire electrode electric spark forming machine utilizes the flow of compressed air for feeding the used wire into a cutting apparatus that is operated in combination with the wire guide apparatus. The wire guide apparatus includes a guide tube 1 for taking in the used wire from the electric spark forming machine and a compressed air supply section 2. The guide tube 1 has a funnel-shaped wire introducing port 3 formed at the upper end and a wire discharge port at the lower end. The compressed air is injected into the guide tube 1 from the fluid injection path 5 formed in the circumferential wall 1a of the guide tube to smoothly guide the wire 12 from the wire introducing port 3 to the outside of the wire discharge port 4.

BACKGROUND OF THE INVENTION 
FIELD OF THE INVENTION 
The present invention relates to a wire guide apparatus to smoothly guide 
the delivery of a wire used in a wire electrode electric spark forming 
machine and also a wire guide apparatus whereof a wire cutting apparatus 
is installed in the following process. 
DESCRIPTION OF THE PRIOR ART 
A conventional wire electrode electric spark forming machine used for 
manufacturing plastics molding dies, for example, makes holes of specified 
shape in the dies by continuously feeding a wire as an electrode by a 
supply reel and a takeup reel, generating sparks between the wire and the 
dies fixed on the work table, and moving the work table with high 
precision at the same time. 
The wire used as an electrode is normally 0.1 to 0.3 mm in diameter and 
about 5 kg of wire wound on the supply reel is continuously fed out at the 
rate of 80-250 mm/second. 
In wire electrode electric spark forming machines in recent years, because 
the used wire fed out from the discharge roller cannot be reused as is, it 
is considered advantageous to feed the used wire directly from the 
discharge roller indiscriminately into a wire receiving container rather 
than winding it on the takeup reel and to melt it down in a mass for 
reuse. Generally, a wire electrode electric spark forming machine with an 
automatic wire connection function necessarily adopts the above-mentioned 
indiscriminately-receiving method. 
In the indiscriminately-receiving method, when the used wire is 
continuously fed into the wire receiving container, the wire, when piled 
up high, has an apparent specific gravity of approximately one-thirty of 
the wire and occupies a very large space, overflowing the container in a 
short time. Hence, as the wire piles up, it may twist around the discharge 
roller of the wire electrode electric spark forming machine. 
Therefore, a worker needs to watch the flow of the used wire frequently 
during operation, and the procedure to rectify the entanglement of the 
wire is complex and prevents automation of operation. It has therefore 
been conceived to cut the used wire into small pieces, as indicated in the 
Japanese Utility Model Preliminary Publication No. Heisei 2-38141, which 
proposes a wire cutting apparatus K for electric spark forming as shown in 
FIG. 7 herein. 
The wire cutting apparatus K for electric spark forming is installed at the 
end of the wire electrode electric spark forming machine and outs the wire 
c paid out from the wire electrode electric spark forming machine into 
chips 6 cm long by a rotary blade a mounted on a rotating shaft driven by 
a geared motor and a stationary blade b arranged facing the rotary blade 
a, with the cut wire chips accommodated in a separate container. 
That is, the used wire c fed out from the wire electrode electric spark 
forming machine is guided along a guide tube d and gripped by feed rollers 
e. The wire c gripped by the feed rollers e is fed down the side surface 
of the stationary blade b and at the same time clamped and out by the 
rotary blade a and the stationary blade into chips. The wine chips c fall 
along a guide plate f into a separate container. 
With the wire cutting apparatus K for electric spark forming described 
above, however, because there is friction resistance due to contact 
between the used wire c fed out from the wire electrode electric spark 
forming machine and the inner surface of the guide tube d, the wire c may 
get stuck inside the guide tube d bringing the operation to a halt when 
the guide tube d is elongated. This makes it necessary to directly install 
the wire cutting apparatus K at a location very close to the wire 
discharge port of the electric spark forming machine. For this reason, 
impacts produced by the operation of the cutting blade are transmitted to 
the electric spark forming machine degrading the machining precision. 
Further, since the wire cutting is done by a single rotary blade a mounted 
on the rotating shaft and the wire is cut once for each rotation of the 
shaft producing cut chips as long as 6 cm each, the wire volume after 
discharge is not reduced significantly, producing little improvement in 
workability during processing. 
SUMMARY OF THE INVENTION 
This invention has been accomplished to overcome the above-mentioned 
drawbacks and its objective is to provide a wire guide apparatus for an 
electric spark forming machine which smoothly guides the wire fed out from 
the wire electrode electric spark forming machine by utilizing the flow of 
compressed gas. Another object is to provide a wire guide apparatus 
wherein a wire cutting apparatus is installed for operation subsequently 
in the concerned process. 
To achieve the above objective, the wire guide apparatus of this invention 
comprises: 
a guide tube for drawing in a wire; and 
a compressed gas supply section; 
the guide tube including: 
a funnel-shaped wire introducing port formed at one end thereof; 
a wire discharge port formed at the other end thereof; 
a fluid injection path passing through a circumferential wall of the guide 
tube and opening inside the guide tube toward the wire discharge port; 
wherein the wire introducing port of the guide tube is located at a wire 
discharge section of the electric spark forming machine, and the 
compressed gas is injected into the guide tube from the compressed gas 
supply section through the fluid injection path so as to guide the wire 
from the wire introducing port to the outside of the wire discharge port. 
It is preferred that the circumferential wall of the guide tube at the end 
containing the wire introducing port is formed in substantial conformity 
with the shape of the nip between the wire discharge rollers so that the 
tube adjacent the wire introducing port is pointed in a direction toward 
the end thereof. 
It is advantageous if the wire discharge port of the guide tube is 
connected with a flexible tube, through which the wire is discharged. 
Further, the compressed gas is advantageously composed of air, wherein the 
compressed gas pressure being normally set at 1.0 to 2.0 kg/cm.sup.2 at a 
pressure reducing valve. 
And, a wire cutting apparatus can be also preferably installed downstream 
of the wire guide apparatus for an electric spark forming machine of this 
invention, wherein the chip length delivered by the wire cutting apparatus 
being set at around 2 to 5 mm. 
Because the wire guide apparatus for an electric spark forming machine 
according to this invention employs a guide tube that utilizes the flow of 
compressed gas, the used wire discharged from the electric spark forming 
machine can reliably be drawn into the guide tube toward the wire 
discharge port. That is, a compressed gas is blown into the guide tube 
from the fluid injection path, causing the gas in the guide tube to 
rapidly flow toward the wire discharge port, so that a negative pressure 
is created in a space extending from the opening of the fluid injection 
path to the wire introducing port, drawing the air around the wire 
introducing port into the guide tube. 
Since the wire introducing port of the guide tube is located close to the 
wire discharge section of the electric spark forming machine, the wire fed 
out from the electric spark forming machine is drawn into the guide tube 
together with the gas around the wire introducing port. In the guide tube, 
the flow of compressed gas mostly eliminates the friction resistance 
between the inner wall of the guide tube and the wire, so that the wire 
does not get stuck in the guide tube and is fed smoothly along the 
discharge port. 
This makes it possible to connect a flexible tube to the wire discharge 
port to virtually elongate the guide tube, which in turn permits the wire 
to be guided from the wire discharge section of the electric spark forming 
machine to a remote wire accommodating section. 
Further, by pointing the wire introducing port by forming the 
circumferential wall of the guide tube, it is possible to bring the 
opening end of the wire introducing port extremely close to the nip of the 
rollers of the wire discharge section of the electric spark forming 
machine, permitting an efficient suction of wire. 
Moreover, by arranging the wire discharge port of the guide tube or the 
flexible tube connected to the wire discharge port close to the cutting 
blade of the wire cutting apparatus, it is possible to cut and process the 
used wire immediately after it is discharged from the wire guide 
apparatus. 
And, the use of the transparent flexible tube allows quick and reliable 
check of the wire being guided.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
FIG. 1 shows a side view of a wine guide apparatus A for an electric spark 
forming machine as one embodiment of this invention. 
The wire guide apparatus A comprises a guide tube 1 and a compressed gas 
supply section 2. 
The guide tube 1 is formed of a stainless steel tube body, which has a 
funnel-shaped wire introducing port 3 at the upper end and a wire 
discharge port 4 at the lower end. Near the wire introducing port 3, a 
circumferential wall 1a is formed with a fluid injection path 5, which 
passes through the circumferential wall 1a in a direction inclined toward 
the wire discharge port 4 and opens inside the guide tube 1. 
The compressed gas supply section 2 delivers compressed air, which is 
supplied from a compressor through an air supply pipe 6, to the fluid 
injection path in the guide tube 1 through an air filter 7 and a pressure 
reducing valve 8. 
The air filter 7 is designed to remove foreign substances contained in the 
compressed air supplied through the air supply pipe 6, thereby protecting 
the whole equipment from failing due to foreign matter clogging the wire 
guide path. 
The pressure reducing valve 8 adjusts the air pressure injected from the 
fluid injection path 5 according to the distance that the wire 12 is 
guided. Normally, the air pressure is preferably set at 1.0 to 2.0 
kg/cm.sup.2. 
To guide the used wire discharged from the electric spark forming machine, 
the wire introducing port 3 of the guide tube 1 is located close to the 
nip of the wire discharging rollers 9, 9' of the electric spark forming 
machine, and a wire accommodating box 11 is installed at the end of a 
flexible transparent plastic tube 10 connected to the wire discharge port 
4 of the guide tube 1. 
When the compressed air is injected into the guide tube 1 through the 
pressure reducing valve 8, the flow of compressed air blowing from the 
fluid injection path 5 toward the wire discharge port 4 creates a negative 
pressure in the wire introducing port 3, thus drawing the wire 12 
discharged by the nip of the rotating rollers 9, 9' from the wire 
introducing port 3 into the guide tube 1. 
The wire 12 drawn into the guide tube 1 is fed through the flexible tube 10 
connected to the wire discharge port 4 and is then received into the wire 
accommodating box 11. The flexible tube 10 may be formed of rubber, 
synthetic resin, and metal. Of these materials, a synthetic resin is 
preferred because it allows one to see the interior and easily check the 
condition of wire 12 being guided. Instead of connecting the flexible tube 
10 to the wire discharge port 4, it is also possible to receive the wire 
directly into the wire accommodating box 11. 
FIG. 2 is a longitudinal cross section of the guide tube 13 associated with 
another embodiment of this invention. FIG. 3 is a plan view of the guide 
tube 13. 
The guide tube 13, like the aforementioned guide tube 1, is formed of a 
metallic tube and has a funnel-shaped wire introducing port 14 at the 
upper end and a wire discharge port 4' at the lower end and also a fluid 
injection path 5' formed in the circumferential wall 13a. 
The funnel-shaped wire introducing port 14 of the guide tube 13 is pointed 
by cutting the circumferential wall 13a to form on the left and right side 
of the central axis of the guide tube 13 recessed cylindrical surfaces 15, 
15' whose contour conforms to the outer diameter of the nip of the wire 
discharge rollers 9, 9' of the electric spark forming machine installed 
facing the guide tube. 
By providing the wire introducing port with the arcuate surfaces 15, 15', 
it is possible to bring the pointed part of the wire introducing port 14 
very close to the wire gripping point of the nip of the wire discharge 
rollers 9, 9'. This makes the suction of wire reliable. 
While the above embodiments have been explained in the case where they are 
used for the guiding of used wire, it should be noted that the wire guide 
apparatus of this invention is not limited to the guiding of used wire but 
can also be used for wire guiding in the wire supply process before the 
spark process. 
FIG. 4 is a perspective view of a wire cutting apparatus B to be combined 
with the wire guiding apparatus for an electric spark forming machine. 
The wire cutting apparatus B includes a small motor 17 rigidly mounted on a 
support stand 16, a rotary blade fixing mount 18, a stationary blade 
mounting plate 19, and a chip box 20 located immediately below the rotary 
blade fixing mount 18. 
On the side surface 18a of the rotary blade fixing mount 18 is provided a 
bearing 22 that supports the rotating shaft 21b of the rotary blade 21 
having a plurality of cutting edges 21a on its periphery. The rotating 
shaft 21b is connected to the small motor 17 through a coupling 23. 
On the upper surface 18b of the rotary blade fixing mount 18 is removably 
mounted a stationary blade mounting plate 19 that has a funnel-shaped wire 
insertion opening 24. 
The stationary blade mounting plate 19 has a stationary blade 25 of hard 
steel mounted to the underside thereof along the wire insertion opening 
24. 
At the wire insertion opening 24 of the wire cutting apparatus B is placed 
a flexible tube 10 of the above embodiment to guide and introduce the wire 
12 fed out by the wire discharge rollers 9, 9' of the electric spark 
forming machine into the wire insertion opening 24 through the guide tube 
13 and the flexible tube 10. 
In more detail, the guide tube 13 is installed close to the nip of the wire 
discharge nip rollers 9, 9', and the compressed air delivered through the 
air supply pipe 6 and through the air filter 7 and the pressure reducing 
valve 8 is injected from the fluid injection path 5' into the guide tube 
13 as indicated by the arrow. 
The wire 12 is guided by the flow of compressed air and fed through the 
flexible tube 10 into the wire insertion opening 24 of the wire cutting 
apparatus B. The rotary blade 21 is rotated in the direction of arrow to 
cut the wire by the cutting edges 21a of the rotary blade 21 and the 
stationary blade 25 into small chips that fall onto the chip box 20. The 
small chips are forcibly discharged into the chip box 20 by the compressed 
air flowing into the wire insertion opening 24 and therefore do not get 
stuck to the rotary blade 21. 
The length of the cut wire chips is determined by the rate of supply of the 
wire 12 and the circumferential speed of the cutting edge 21a of the 
rotary blade 21. As the chip length becomes large, a large accommodating 
space is required. On the other hand, if the chip length reduced, the 
process speed is slowed down, lowering the productivity. It is therefore 
preferred to set the chip length at around 2 to 5 mm. 
In the above embodiments, explanation is given as to the case where the 
above-mentioned guide apparatus is used in combination with the cutting 
apparatus that uses the rotary blade. It is noted, however, that the 
structure of the cutting apparatus is not limited. For example, the guide 
apparatus of this invention may be used in combination with a cutting 
apparatus that uses a reciprocating cutting blade. 
FIG. 6 is a perspective view of a wire cutting apparatus C equipped with a 
wire guide apparatus for an electric spark forming machine as a further 
embodiment of this invention. 
The wire cutting apparatus C includes a small motor 27 on the support stand 
26, a rotary blade fixing mount 28, a stationary blade mounting plate 29, 
and a case 30 of plastics enclosing these. Immediately below the rotary 
blade fixing mount 28 is located a chip box 33. In addition to the small 
motor 27, rotary blade fixing mount 28 and stationary blade mounting plate 
29, the case 30 also accommodates an air filter 31 and a pressure reducing 
valve 32 as a compressed air supply section. 
In the rotary blade fixing mount 28, a rotary blade like the one used in 
the previous embodiment is mounted, though not shown, to the rotating 
shaft 34 and is driven by the small motor 27 via the coupling 35 to cut 
the wire. 
The stationary blade fixing plate 29 is formed with a funnel-shaped wire 
insertion opening 36, and the end of the flexible tube 10 connected to the 
guide tube 13 as in the preceding embodiment is inserted into the case 30 
and into the wire insertion opening 36. 
The case 30 are provided with a compressed air introducing port 37 and a 
compressed air delivery port 38. An air supply pipe 39 is passed through 
the compressed air introducing port 37 and connected to the air filter 31, 
which in turn is connected to the pressure reducing valve 32 and through 
the compressed air delivery port 38 to a flexible air delivery tube 40 of 
rubber or nylon, which runs parallel to the flexible tube 10 and is 
connected to the fluid injection path 5' of the guide tube 13. 
The wire introducing port 14 of the guide tube 13 is located close to the 
nip of the wire discharge rollers 9, 9' to guide the wire 12 fed out by 
the nip rollers 9, 9' through the guide tube 13 and flexible tube 10 into 
the wire insertion opening 36 for cutting. 
Because the wire cutting apparatus C has the cutting mechanism and the 
compressed air supply section accommodated in the case 30, it is easily 
moved to a desired location and operated simply by connecting to an 
external pressurized air source. At the same time, since the guide tube 13 
is connected to the flexible tube 10 and the flexible air delivery tube 
40, the wire cutting apparatus C has the advantage of being able to be 
installed easily at an appropriate position near the nip of the wire 
discharge rollers 9, 9'. It can also be connected to and disconnected from 
the guide tube 13. 
Because the wire guide apparatus for electric spark forming machine 
according to this invention uses a guide tube that utilizes the flow of 
compressed gas, the used wire discharged from the electric spark forming 
machine can reliably be drawn into the guide tube and fed smoothly to the 
wire discharge port. The flow of the compressed gas prevents the wire from 
getting stuck in the inner wall of the guide tube. 
Therefore, by connecting the flexible tube to the wire discharge port, it 
is possible to guide the wire from the wire discharging section of the 
electric spark forming machine to the wire accommodating section at a 
remote location, making it unnecessary to directly mount to the electric 
spark forming machine the cutting apparatus that generates vibrations. 
This in turn prevents unwanted vibrations from being transmitted to the 
electric spark forming machine that is required of high machining 
precision. 
The fact that the used wire can be guided to an appropriate location for 
processing contributes to effective utilization of space. 
By pointing the circumferential wall of the wire introducing port of the 
guide tube, it is possible to bring the opening end of the wire 
introducing port very close to the nip of the rollers of the wire 
discharge section of the electric spark forming machine, ensuring an 
efficient suction of wire and improving reliability. 
The use of the transparent flexible tube allows quick and reliable check of 
the wire being guided, ensuring a smooth wire processing work and an 
improved productivity.