JPH0610479B2 - Molding method of blade part of injection mold of cylindrical impeller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a blade portion of an injection molding die for a tubular impeller such as a cross fan (cross flow fan) and a sirocco fan.

[Prior art]

As shown in FIG. 1, a cross fan or a sirocco fan has a large number of blades 2 which are long in the longitudinal direction along a cylindrical outer peripheral surface.
Are arranged in rows, and each of the blades has a very complicated shape such that the cross section is approximately a three-month shape, so conventionally, many blades were assembled and assembled, but recently, With the ease of forming complex dies by wire-cut electric discharge machining, the dies for tubular impellers have been improved so that they can be assembled with a few combinations of dies.

As is well known, wire-cut electrical discharge machining has a diameter of 0.02-0.
While using a thin metal wire of 3 mm as an electrode to control the machining feed of the table by NC control and move it to a predetermined shape,
It is an electric discharge machining method that cuts out a two-dimensional shape in a thread saw type.

Melting machining of metal using the spark electric discharge phenomenon is similar to conventional electric discharge machining, but in contrast to conventional electric discharge machining,
It is possible to punch through complicated shapes without making all-shape electrodes. The processing system can be accurately controlled by NC control. Since the wire is disposable and always sent new, the electrode consumption can be ignored. Since a thin wire is used as the electrode, the machining margin is small and expensive materials are saved. The surface roughness is
It has a number of excellent advantages such as around 10μ, which generally does not require post-finishing.

However, with impellers that are mainly used in air conditioners for home use, such as cross fans and sirocco fans, it is necessary to prevent noise generation and reduce power consumption in particular, and also to save materials from the viewpoint of cost. Therefore, it is strongly required to form each blade in a thin shape, but it is difficult to form a thin shape by wire cut electric discharge machining.

That is, as shown in FIG. 3, when molding the core 3, the mold material P as a working material is cut out in a circular shape, and the cut groove 13 is molded, and at the same time, the blade 2 is molded inward from the cut groove 13. 5 is cut, but since the molding part 5 is substantially a three-month shape, when the wire 6 forms the molding part 5, as shown in FIG. The scrap 7 dropped and came into contact with the wire 6 and the mold material P and short-circuited between them, and the wire could not be machined and the machine automatically stopped.

If the width of the inlet 8 of the forming part 5 is wide, that is, if the outer end of the cross section of the blade 2 is thick, it is possible to process the forming part 5 with the scrap piece 7 attached to the outer mold 10 and cause a short circuit trouble. Although it can be avoided, as described above, when the requirement for reducing the wall thickness of the blade 2 is satisfied, the width of the inlet 8 is inevitably narrowed, and the material of that portion is completely melted when the wire 6 moves in and out, so that the scrap 7 Will occur independently.

Another possible measure to prevent shorting is to make the wire 6 thicker or thinner. When the thick wire 6 is used, the cutting groove width is widened, so that the scrap pieces 7 are not generated in a part of the blade forming portion 5, but the blade 2
Since the base has a large wall thickness at the base end due to the draft, the generation of the scrap 7 at the base end molding site is unavoidable. If thin wire 6 is used, remove scrap 7
Although it is possible to prevent the wire 6 from falling by leaving it attached, there is a limit to making the wire 6 thin, and if an excessive current is applied to maintain the processing speed, a disconnection problem easily occurs.

[Object of the Invention]

In view of the actual situation of molding the conventional blade portion as described above, the present invention melts the molding portion of the blade of the mold material,
It is an object of the present invention to provide a die-molding method for a die for injection molding of a tubular impeller that does not generate scraps.

[Structure of Invention]

The structure of the present invention for achieving the above-mentioned object is to cut out a central portion of a mold material in a circular shape by wire cut electric discharge machining to form a cut groove, and at the same time, to perform electric discharge machining of a blade forming portion by advancing a wire from the cut groove. In the method of forming the blade portion of the injection molding die of the tubular impeller, when the wire is advanced from the cutting groove to the processing range of the blade forming section, first the wire width electric discharge machining is used to melt the central part of the width of the possible range, and then the The gist of the invention is a method of forming a blade portion of a mold for injection molding of a cylindrical impeller, which melts the periphery of the hollow groove to form a blade processing surface.

〔Example〕

 Hereinafter, the method of the present invention will be described with reference to the drawings.

FIG. 3 shows a molding procedure of the core 3 of the injection molding die of the tubular impeller F.

According to this, the through hole 11a, 11b, 11c of the wire 6 is formed in the mold material P.
By installing 3 points, the end cuts 12,1
Arc-shaped cut grooves 13a, 13b, which are separated from each other by 2, 12.
13c is formed, and the blade 6 is formed on the core 3 by cutting the wire 6 from the arcuate cut grooves 13a, 13b, 13c. At the end, die cutting is performed by cutting each end cut portion 12 with a wire. Until then, since the core 3 is held by the end cut portions 12, 12, 12, the already formed processing is performed. Precisely trace the surface with wire 6,
The work makes it possible to make the processed surface finer and smoother. However, the present invention is not limited to such a processing method, and can be applied to a general die-cutting case in which the end cut portion 12 is not provided.

The mold material P is fixed to a table controlled by X-axis and Y-axis, and the mold material P is processed by the movement of the table.

The blade forming section 5 is formed by cutting each arcuate cut groove 13a, 13b, 13c.
At the time of molding, as shown in FIG. 4, (formed in order), from the arc-shaped cut groove 13 toward the blade forming part processing range 15, and proceed to the width center part of the range 15, and its center A hollow groove 18 is formed in the part until it reaches near the inner part, and then, as shown in FIG.
Then, the wire 6 is moved along the planned machining line 16a of the machining surface 16 of the blade forming portion 5 to move to the machining surface 16
Is formed over the entire circumference. Then, when the wire 6 returns to the arcuate cut groove 13 again, the wire 6 advances along the position 20 where the cut groove 13 is to be formed, and goes to the next blade forming portion 5.

In the case where the width-removing groove 18 is first formed in the width center portion of the planned awning area 15 of the blade forming portion 5, the portion is melted and falls as a small scrap, which may be caught on the wire 6. Also, even if the machined surface 16 is formed over the entire circumference next time, since the inside is cut out, long scraps that may be caught on the wire 6 do not occur.

In the case of the above embodiment, the blade forming section 5 of the mold is used.
The blade 2 of the cylindrical impeller is made by making the processing surface 16 of the
It is suitable for forming a cylindrical impeller F having very little air resistance, because both the outer surface of the blade can be formed smoothly and the blade 2 can be formed thin by narrowing the width of the blade forming portion 5. .

〔The invention's effect〕

As described above, according to the method of the present invention, when the wire is advanced from the cut groove to the processing range of the blade forming portion, the central portion of the width of the processing range is first melted by the wire cut electric discharge machining to form the hollow groove. Since it is formed, there is no generation of a scrap piece that causes a short circuit on the wire, and there is an excellent effect that it is possible to prevent processing failure or machine stoppage due to a short circuit.

[Brief description of drawings]

FIG. 1 is a perspective view of a tubular impeller, FIG. 2 is an explanatory view showing a conventional method of forming a blade portion, and FIG. 3 is an explanatory view showing an example of a molding procedure of a core, FIGS. 4 and 5. The drawings are sectional views showing the procedure for forming the blade forming portion according to the present invention. F …… cylindrical impeller, P …… shaped material, 5 …… blade forming part 6 …… wire, 13,13a, 13b, 13c …… cutting groove 15 …… blade forming part processing range 16 …… blade processing surface , 18 ... hollow groove

Claims (1)

[Claims] An injection molding of a cylindrical impeller, wherein a central portion of a mold material is cut out in a circular shape by wire cut electric discharge machining to form a cut groove, and a blade forming portion is formed by electric discharge machining by advancing a wire from the cut groove. In the blade forming method of the metal mold for use in advancing the wire from the cut groove to the processing range of the blade forming section, by wire-cut electric discharge machining, first, the central portion of the width of the processing range is melted to form a hollow groove,
Then, a method of forming a blade portion of a mold for injection molding of a cylindrical impeller, which melts the periphery thereof to form a blade processing surface.