KR20130063639A - Method for manufacturing piston ring of die casting machine and piston ring made by the method - Google Patents

Abstract

PURPOSE: A piston-ring manufacturing method for a die casting device is provided to decrease a manufacturing cost due to remove a waste of a material by manufacturing the piston-ring in a centrifugal casting mode. CONSTITUTION: A piston ring manufacturing method for a die casting device comprises the following steps: a step(S2) aims to centrifugal cast a molten metal with being adhered closely to an inner periphery of a cavity by rotating a centrifugal casting mold at a fixed revolutions per minute(RPM) with injecting the molten metal into an inside of the cavity of the centrifugal casting mold; a step(S3) aims to anneal a semi finished product of the piston ring which is center casted in the cavity of the centrifugal casting mold; and a step(S4) aims to manufacture a complete product of the piston ring by processing the semi finished product of the piston ring to a fixed form and a fixed dimension. [Reference numerals] (AA) Start; (BB) LOT No. marking; (CC) Cutting incision unit by 45°; (DD) Completion; (S1) Manufacturing master alloy; (S2) Injecting master alloy into a centrifugal casting mold and manufacturing centrifugal casting; (S3) Annealing; (S4) Cutting internal and external diameter/; (S5) Home cutting; (S6) Low pressure plasma ion nitrification heating process

Description

Method for manufacturing piston ring for die casting device and piston ring manufactured by the method {Method for Manufacturing Piston Ring of Die Casting Machine and Piston Ring Made by the Method}

The present invention relates to a method of manufacturing a piston ring for a die casting apparatus, and more particularly, to a method of manufacturing a ring of a piston for performing an action of injecting molten metal into a mold in a die casting apparatus such as a magnesium alloy high temperature chamber die casting apparatus. It relates to a piston ring produced by the manufacturing method.

As is well known, a die casting apparatus is a device for molding a product by injecting molten metal into a cylinder and injecting the piston rod to a predetermined pressure into a mold connected to the cylinder.

Therefore, in order to easily inject the molten metal injected into the cylinder into the mold in the die casting apparatus as described above, the piston of the piston rod mounted in the cylinder must maintain a certain strength and brittleness, while maintaining the airtightness between the outer surface of the piston and the inner circumference of the cylinder. The piston should slide smoothly.

Therefore, as shown in FIG. 1, the ring 3 is mounted when the piston 2 moves along the inside of the cylinder by mounting the metal ring 3 on the outer circumferential surface of the piston 2 coupled to the end of the piston rod 1. The molten metal is pushed out by sliding in contact with the inner circumferential surface of the cylinder.

The ring 3 mounted on the piston 2 is required to have high durability and strength, and in the related art, a ring is manufactured in a forged manner to satisfy the durability and strength.

However, when manufacturing the ring 3 in the forging method is expensive, a lot of time and effort is consequently there is a problem that increases the manufacturing cost of the ring.

The present invention is to solve the above problems, an object of the present invention is to provide a method of manufacturing a piston ring for a die casting device that can reduce the manufacturing cost, and can reduce time and effort.

Another object of the present invention is to provide a piston ring for a die casting device which is manufactured by the above-described manufacturing method and which can increase durability and strength.

In order to achieve the above object, the present invention provides a method of manufacturing a piston ring mounted on an outer circumferential surface of a piston of a die casting apparatus, the method comprising: (a) injecting a predetermined amount of molten metal into a cavity of a centrifugal casting mold and simultaneously centrifugal casting; Rotating the mold at a set rotational speed (rpm) to bring the molten metal into close contact with the inner circumferential surface of the cavity to centrifugally cast the molten metal; (b) annealing the centrifugally cast piston ring semifinished product in the cavity of the centrifugal casting mold; (C) provides a piston ring manufacturing method for a die casting device comprising the step of making the piston ring finished product by processing the semi-finished piston ring in the set shape and dimensions.

According to the present invention as described above, since the piston ring can be manufactured in a centrifugal casting method, waste of material is eliminated, and manufacturing cost can be reduced, and time and effort can be reduced.

In addition, while producing a piston ring using the production method of the present invention, by producing a piston ring in the composition and composition ratio proposed in the present invention can be improved durability and strength.

1 is a front view showing a piston rod for a conventional die casting apparatus.
Figure 2 is a schematic diagram showing the structure of a magnesium alloy high temperature chamber die casting apparatus to which the piston ring of the present invention is applied.
3 is a perspective view of a piston ring manufactured by the manufacturing method according to the present invention.
4 is a flowchart illustrating a method of manufacturing a piston ring for a die casting apparatus according to a preferred embodiment of the present invention.
Figure 5 is a cross-sectional view schematically showing the centrifugal casting mold for performing the piston ring manufacturing method for die casting apparatus according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the piston ring manufacturing method for a die casting apparatus according to the present invention and the piston ring produced by this manufacturing method.

First, FIG. 2 schematically shows the structure of a magnesium alloy high temperature chamber die casting apparatus to which a piston ring of the present invention is applied. The magnesium alloy high temperature chamber die casting apparatus includes a melting furnace 10 in which molten metal is accommodated, and the melting furnace 10. The cylinder part 50 (') installed inside and connected to the die casting mold 30 through the nozzle 20 to transfer the molten metal in the melting furnace 10 to the mold 30 by the reciprocating motion of the piston rod 40 (' also known as goose neck ').

The piston ring 42 is coupled to the outer circumferential surface of the piston 41 coupled to the end of the piston rod 40. The piston ring 42 has a diameter of approximately 70 mm. As shown in FIG. 3, the piston ring 42 is inclined at one side at an angle of 45 degrees, and may be formed of an open structure ring having a long groove 42b formed at the center of the cutout 42a. have. In this embodiment, the cutout 42a of the piston ring 42 has a form cut obliquely at an angle of 45 degrees, but alternatively, the cutout 42a is vertically cut in a straight line, or has a '' 'shape. It may be incised alternately.

The piston ring 42 is 0.17 to 0.23% by weight of carbon (C), 0.15 to 0.35% by weight of silicon (Si), 0.4 to 0.6% by weight of manganese (Mn), 0.01 to 0.03 weight of phosphorus (P) or sulfur (S) %, Chromium (Cr) 9.0-10.0 wt%, molybdenum (Mo) 1.8-2.2 wt%, tungsten (W) 5.0-6.0 wt%, cobalt (Co) 9.5-10.5 wt%, residual composition ratio of iron (Fe) Is made of.

Hereinafter, a method of manufacturing the piston ring 42 as described above will be described.

Referring to FIG. 4, in the method of manufacturing a piston ring for a die casting apparatus according to a preferred embodiment of the present invention, a step (S1) of refining a metal in a molten metal bath to produce a predetermined amount of a master alloy is performed. Melting and injecting into the cavity of the centrifugal casting mold and rotating the centrifugal casting mold at a predetermined rotational speed (rpm) to bring the molten metal into close contact with the inner circumferential surface of the cavity (S2); Annealing the centrifugally cast piston ring semi-finished product in the cavity of the centrifugal casting mold (S3), cutting the inner and outer diameters of the semi-finished piston ring semifinished product, and adjusting dimensions and roughness through outer diameter finishing (S4), cutting the groove (42b) of the piston ring semifinished product (see Fig. 3), performing a low pressure plasma ion nitriding heat treatment of the piston ring semifinished product (S6), and manufacturing lot number (LOT No.), and cutting the cut-out portion 42a at a 45 degree angle to produce a finished piston ring (S7) and the like.

Each step of the piston ring manufacturing method will be described in more detail as follows.

First, the piston ring composition materials such as iron, carbon, and silicon as described above are introduced into a molten bath, and a predetermined amount of master alloy is manufactured by performing a refining process using argon refining. (Step S1).

Subsequently, as shown in FIG. 5, the master alloy is melted at a set temperature, and the molten master alloy is injected into the cavity 101 of the centrifugal casting mold 100 of a vertical type. The mold 100 is rotated at a speed of 400 to 1000 rpm to closely adhere the master alloy to the inner circumferential surface of the cavity 101 to perform centrifugal casting (step S2). At this time, the master alloy is melted at a melting temperature of 1600 ~ 1700 ℃ and then injected into the centrifugal casting mold (100). Completion of this centrifugal casting step results in a semifinished piston ring in the form of a cylindrical ring.

When the piston ring semifinished product is manufactured through the centrifugal casting step, the piston ring semifinished product is separated from the cavity 101 of the centrifugal casting mold 100 and annealed (step S3). In this annealing step, the semi-finished piston ring is put into the annealing chamber to microstructure the tissue by slowly cooling for 5 hours in an environment of 900-1000 ° C., preferably 950 ° C. At this time, the hardness (Hrc) of the piston ring semi-finished product is 40 or less to facilitate subsequent processing.

When the annealing process is completed, the inner and outer diameters of the semifinished piston ring are cut, the dimensions and roughness are adjusted to the set values through external finishing (step S4), and the grooves 42b of the semifinished piston ring are cut (see FIG. 3). The semi-finished piston ring is machined to the specified shape and dimensions.

Then, a low pressure plasma ion nitriding heat treatment is performed (step S6). By the low pressure plasma ion nitriding heat treatment, the surface of the piston ring 42 is oxidized and nitrided to a thickness of about 0.15 mm to increase the hardness of the surface, thereby increasing the durability and wear resistance of the piston ring. After the low pressure plasma ion nitriding heat treatment, the surface hardness (Micro Vickers Hardness (HV)) of the semifinished piston ring is about 1200.

After the low pressure plasma ion nitriding heat treatment, the lot number (LOT No.) or the like is manufactured on the surface of the semi-finished piston ring, and the cut portion 42a is cut at an angle of 45 degrees (step S7). This makes the piston ring 42 finished product.

According to the present invention, since the piston ring 42 is made by centrifugal casting, not only can reduce the manufacturing cost and time, but also bubbles or non-metallic deposits are removed during the centrifugal casting process, and the structure of the tissue by the centrifugal force is removed. The advantage that the density and strength can be obtained can be obtained.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. In addition, it is apparent that any person having ordinary knowledge in the technical field to which the present invention belongs may make various modifications and imitations without departing from the scope of the technical idea of the present invention.

10: melting furnace 20: nozzle
30: die casting mold 40: piston rod
41: piston 42: piston ring
42a: Incision 42b: groove
50: cylinder portion 100: die casting mold
101: cavity

Claims (7)

In the method for manufacturing a piston ring mounted on the outer peripheral surface of the piston of the die casting device,
(a) injecting a predetermined amount of molten metal into the cavity of the centrifugal casting mold and simultaneously rotating the centrifugal casting mold at a predetermined rotational speed (rpm) to bring the molten metal into close contact with the inner circumferential surface of the cavity to centrifugally cast;
(b) annealing the centrifugally cast piston ring semifinished product in the cavity of the centrifugal casting mold;
(C) a method for producing a piston ring for die casting device, characterized in that for processing the piston ring semi-finished product in a set shape and dimensions to make a finished piston ring. The method of claim 1, wherein in the step (b), centrifugal casting is performed by rotating a centrifugal casting mold of a vertical type at a speed of 400 to 1000 rpm. The method of claim 1, wherein before the step (a) to refine the metal in the molten bath to produce a master alloy (master alloy), in the step (a) is characterized in that the molten alloy is added to the centrifugal casting mold. A piston ring manufacturing method for die casting apparatuses. The method of claim 1, wherein in the step (a), the master alloy is melted at a dissolution temperature of 1600 to 1700 ° C and then injected into a centrifugal casting mold to perform centrifugal casting. The method of claim 1, wherein the piston ring semi-finished product is subjected to low pressure plasma ion nitriding heat treatment during the step (c). The method of claim 1, wherein the step (b) is a piston ring manufacturing method for a die casting device, characterized in that for 5 hours in an environment of 900 ~ 1000 ℃. Prepared by the method of any one of claims 1 to 6, the carbon (C) 0.17 ~ 0.23% by weight, silicon (Si) 0.15 ~ 0.35% by weight, manganese (Mn) 0.4 ~ 0.6% by weight, phosphorus ( P) or 0.01 to 0.03 wt% sulfur (S), 9.0 to 10.0 wt% chromium (Cr), 1.8 to 2.2 wt% molybdenum (Mo), 5.0 to 6.0 wt% tungsten (W), 9.5 to 10.5 cobalt (Co) A method for producing a piston ring for a die casting device, characterized in that the composition comprises a percentage by weight of iron (Fe).

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