JPS63306018A - Method for working pinpoint gate - Google Patents

Abstract

PURPOSE:To efficiently work a pinpoint gate in a short time by a method wherein a sprue part is worked in taper with a taper cutter and, after that, a gate part is worked with a pyramidal cutter. CONSTITUTION:One or a plurality of pinpoint gates 1 are made at the predetermined locations of a mold piece 7. In addition, each gate consists of a sprue part 3, in which resin such as polystyrene or the like is poured, and a gate part 5, through which the resin poured in the sprue part 3 is injected under high pressure towards a mold. Prepared holes are worked at three locations of a mold piece 7 and, after that, a sprue part 3 having a taper, both adjoining angle of which is 3 deg., is worked with a two-edged straight fluted taper bore cutter 9 at each prepared hole. After sprue parts are respectively worked at the three locations of the mold piece 7, a gate part 5 having a taper, both adjoining angle of which is 30 deg., is worked with a quadrangular pyramidal cutter 11, both adjoining angle of which is 30 deg., at each sprue part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for processing a pinpoint gate of an injection mold.

[Prior Art] Conventionally, machining of a pinpoint gate in an injection mold involves two steps: drilling a pilot hole in a mold piece, and then performing electric discharge machining on the sprue portion and the gate portion of the pinpoint gate, respectively. The sprue part was prepared by electrical discharge machining, and the gate part was electrically discharged while measuring the hole diameter using a pin gauge or the like.

[Problems to be solved by the invention] As mentioned above, in the case where the sprue part and the gate part are electrically discharge-machined using an electrode for electrical discharge machining, the machining process not only takes a very long time, but also causes wear and tear on the electrode. As a result, the hole diameter must be repeatedly measured for each pinpoint gate during machining, resulting in problems such as extremely low efficiency.

[Object of the invention] The present invention solves the above problems, and an object thereof is to provide a processing method that can efficiently process a pinpoint gate of an injection mold in a short time. .

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a first step of tapering the sprue portion with a tapering cutter;
A second step of machining the gate portion with a pyramidal cutter is followed by means of machining the pinpoint gate.

[Function] According to the method described above, the sprue portion is taper-processed using a taper cutter, and then the gate portion is processed using a pyramidal cutter, and processing can be performed in a short time.

[Example] An example embodying the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, the pinpoint gates 1 are formed at predetermined locations on the mold piece 7, or in plural numbers.
It is comprised of a sprue part 3 into which a resin such as polystyrene is injected, and a gate part 5 for injecting the resin injected into the sprue part 3 toward a molding die at high pressure.

Below, the method for processing the pinpoint gate will be explained step by step.

(1) Prepared hole machining process Prepare a prepared hole with a diameter slightly smaller than the hole diameter of the gate part 5 that you want to process.
After machining three locations on the mold piece 7 using drills from below in FIG. 2, drilling is repeated from above using several drills to make pilot holes.

(2) Sprue part machining process - After drilling pilot holes at three locations on the mold piece 7, tapers of 3° on both sides are made using a taper ball cutter 9 with a two-wedge straight groove as shown in Fig. 3. Process the sprue portion 3 having the sprue portion 3.

(3) Gate part processing process After the sprue parts are processed at three locations on the mold piece 7, the fourth
A gate portion 5 having a taper of both corners 30' as shown in FIG. 5 is processed using the quadrangular pyramidal cutter 11 with both corners 30' shown in the figure.

The results of processing according to the above processing steps will be explained.

After drilling a pilot hole in the mold piece 7 having a thickness of 3 Q mm, a taper ball cutter 9 with a 2-wedge straight groove (tool material: ultrafine grain carbide, offset amount 20, 15 to 0.25
mm>, the rotation speed is 60 Or, p, m, , the feed rate is 2 to 3 mm/min, and the depth is 29 from the top surface of the mold piece 7.
．． As a result of machining the sprue portion 3 to a thickness of 1 mm, the machining time per location was 11 minutes.

Furthermore, after the sprue part 3 is processed, a square pyramid cutter 11 (
Feed the cutter to a depth of 30.9 mm from the upper surface of the mold piece 7 at a rotation speed of 200 Or, p, m, and a feed rate of 1 mm/min using a tool material: ultrafine grain carbide, both corners: 30'',
As a result of machining the gate portion 5, the machining time per location was 2 minutes.

It should be noted that machining the pilot holes of the sprue portion 3 and the gate portion 5 required 20 minutes in the same manner as machining by electrical discharge machining, so the total machining time required 33 minutes.

Therefore, when electrical discharge machining a pinpoint gate, approximately 3
What used to be time-consuming has been significantly shortened.

In addition, as described above, the surface roughness of the cut surface of the six pinpoint gates 1 was adjusted to a depth of 5 mm from the top surface of the mold piece 7.
Table 1 shows the results of measurements made using a surface roughness meter at positions of mm, 1Qmm, and 15mm.

Table 1: Surface roughness of the cut surface (μmR7) According to Table 1, the surface roughness of each pinpoint gate is approximately within 1.0μmR2 at any measurement location, so the pinpoint gate was cut by electrical discharge machining. The surface roughness was significantly improved compared to the 10 μm RZ measured during processing. Therefore, the lapping process that was required when electrical discharge machining was performed on pinpoint gates could be omitted, resulting in extremely high machining efficiency.

[Effects of the Invention] As detailed above, in the present invention, the sprue part is tapered with a taper cutter, and then the gate part is machined with a pyramidal cutter, so that pinpoint gates can be machined efficiently in a short time. It has the effect of

[Brief explanation of the drawing]

Figure 1 is a plan view of a mold piece with a pinpoint gate machined, Figure 2 is an enlarged sectional view taken along the line A-A in Figure 1, and Figure 3 (shows a taber ball cutter with a straight groove with two blades). 4 is a front view showing a square pyramid cutter, and FIG. 5 is an explanatory diagram showing a state in which a gate part is processed by a square pyramid cutter. In the figure, 1 is a pinpoint gate, and 3 is a sprue part. , 5 is a gate part, 9 is a two-blade straight groove taper ball cutter, and 11 is a pyramidal cutter.

Claims (1)

[Claims] 1. Consists of a first step of tapering the sprue portion (3) with a taper cutter (9), and a second step of machining the gate portion (5) with a pyramidal cutter (11). A pinpoint gate processing method featuring: