JP2008087047A - Plunger tip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plunger tip with which a smooth reciprocating movement can be kept for long term without inducing a galling and an abnormal wearing even in the case that a thermal expansion occurs. <P>SOLUTION: In the injection plunger for pushing out molten material toward a metallic wall, in an outer peripheral part 21 of a head 2 constituting this plunger, a cut-off part 5 expecting the thermal expansion is beforehand provided, and the cut-off position of the cut-off part reaches the forming position of a cooling chamber 6 arranged in the plunger head and the cut-off depth (t) of the cut-off part is made to be 1/1000-7/1000 of the head diameter R. Further, the cut-off part is peculiarly formed as a step-state cut-off part which cuts off as parallel with the head outer peripheral surface toward the front part from the cut-off position, as a linear inclining cut-off part which inclines downward as the linear-state toward the front part from the cut-off position and a curved-inclining cut-off which inclines downward as the curving-state toward the front part from the cut-off position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plunger tip of an injection plunger for extruding a molten metal toward a mold, for example, a lateral injection type cold chamber type casting machine, particularly a plunger tip in a cold chamber type die casting machine, in particular, thermal expansion. This relates to a plunger tip considering the above.

A conventional die casting machine generally supplies molten metal to an injection sleeve 4 as shown in FIG. 1 and injects the molten metal into a mold cavity C by an injection plunger 10, and the injection plunger is a plunger rod. The plunger head 1 is screwed and coupled to the tip of 3, and this is slidably inserted into the injection sleeve 4 and reciprocated by the cylinder device.
The plunger head directly touches the molten metal side end surface, and the heat is transferred from the molten side end surface to the inside to thermally expand. Therefore, it is necessary to always cool the inside of the head to prevent thermal expansion. For this reason, various cooling means have been proposed. For example, in Japanese Patent Application Laid-Open Nos. 09-94648, 2006-35308, Utility Model Registration No. 2597165, and Utility Model Registration No. 2597248, a cooling chamber is provided inside the plunger head. A water passage that communicates with the cooling chamber is provided in the jar rod, and the plunger head is cooled by circulating cooling water from the water passage to the cooling chamber.

  Further, as shown in FIG. 8, the plunger head 1 is divided into an outer tip 11 and an inner tip 12, and the outer tip 11 is made of hot tool steel such as SKD61, and the wall thickness is reduced. The cooling water supplied from the water supply port 8 is passed through the water pipe 9 provided on the plunger rod 3 by using a copper alloy or chromium steel having a Cr content of 1.5% by weight or less. The cooling water groove 14 cut in the molten metal side end surface 12a flows from the inner side to the outer side, and further passes around the groove cut in the outer peripheral surface of the inner tip 12 and is returned to the concave portion inside the inner tip 12 so Attempts have also been made to prevent thermal expansion by draining from the drain outlet 18.

Further, as disclosed in Japanese Patent Application Laid-Open No. 2004-298908, a ring is fitted to the spigot portion of the ranger head (the corner portion where the outer peripheral surface of the plunger head intersects the molten metal side end surface, that is, the front outer peripheral portion). Has also been proposed.
JP 09-94648 A JP 2006-35308 A Japanese Patent No. 3378206 Utility Model Registration No. 2597165 Utility Model Registration No. 2597248 JP 2004-298908 A

Although the plunger head is cooled by the cooling water, it is almost impossible to cool uniformly. Especially in the plunger head as shown in FIG. 8, the cooling effect by the cooling water is shown in FIG. As shown in the temperature distribution diagram showing the cooling effect in the non-heated state, the inner part between the outer peripheral part of the head and the front part (front outer peripheral part) extends to the outer peripheral side part and the front side part located in the formation range of the cooling chamber. ) Cooling is much inferior. On the contrary, when extruding a high-temperature molten material (in the case of an aluminum alloy molten metal, the temperature is raised to 640 ° C. to 750 ° C. during casting), the molten metal side end face of the head directly touches the molten material, and the heat is shown in FIG. As shown in the heat conduction distribution diagram in the non-cooled state, heat conduction is performed from the molten metal side end surface to the inside of the head, so that the amount of thermal expansion of the inner portion having a poor cooling effect increases. As a result, it is distorted unevenly as a whole, causing kinks and pieces of contact, leading to galling and abnormal wear, and seizure between the thermally expanded plunger head inner part and the inner surface of the injection sleeve. Sometimes occurred.
There is also a problem that the molten metal penetrates into the gap between the plunger heads, which are reduced, and hardens, causing the plunger to stop moving. In addition, there is a problem that the replacement frequency of the expensive plunger head increases and frequent maintenance is required.

Even if the plunger head is divided into an outer head and an inner head and the cooling of the outer head is improved, the outer head fills the cavity with the molten metal at a high pressure. There is a problem that galling, seizure, and abrasion occur because it is heated and rapidly rises in temperature and still undergoes thermal expansion.
Accordingly, the present invention has been made in view of the problems of the prior art, and the object thereof is to provide a spigot portion of an injection sleeve even when the plunger head is suddenly heated from the molten metal side end surface and thermally expanded. It is an object of the present invention to provide a plunger tip that can maintain a smooth reciprocating motion for a long period of time without contact with the surface, without causing galling or abnormal wear.

According to the first aspect of the plunger tip of the present invention, in the injection plunger for extruding the molten metal toward the mold, the plunger tip of the plunger head constituting the injection plunger is cut in anticipation of thermal expansion. A notch portion is provided in advance so that the spigot portion does not come into contact with the injection sleeve even after thermal expansion.
According to a second aspect of the present invention, in the plunger tip according to the first aspect, the cut position of the cutout portion reaches the formation position of the cooling chamber provided in the plunger head.
According to a third aspect of the present invention, in the plunger tip according to the first or second aspect, the cut depth of the notch is 1/1000 to 7/1000 of the head diameter.

Here, the injection plunger is for extruding the molten metal supplied into the injection sleeve toward the mold cavity. The plunger head is screwed to the tip of the plunger rod, and this is connected to the injection sleeve by the cylinder device. The plunger tip is one having a notch portion in the inlay portion of the plunger head.
The inlay portion corresponds to a corner portion where the outer peripheral surface of the plunger head intersects with the molten metal side end surface, that is, the front outer peripheral portion, and the notched portion is a portion notched in the central direction from the plunger head outer peripheral surface. In this case, the plunger head does not expand beyond the head diameter even if the plunger head touches the hot molten metal and thermally expands. As a result, even if the spigot portion expands due to the heat of the molten metal, it is formed in advance with a small diameter in anticipation of the thermal expansion and does not come into contact with the injection sleeve.
The depth of cut refers to the dimension in the center direction from the outer peripheral surface of the head, which is 1/1000 to 7/1000 mm of the head diameter, or 0.01 to 0.08 mm, preferably 0.01 to 0.07 mm. Say.
Here, the cooling chamber is an empty portion provided inside the plunger head, and cooling water is circulated from the plunger rod to cool the plunger head.
Here, the molten metal means a metallic molten metal melted by heating, particularly an aluminum molten metal, and a synthetic resin molten metal.

As a fourth aspect of the present invention, in the plunger tip according to any one of the first, second, and third aspects, the notch is a stepped notch that is notched in parallel with the outer peripheral surface of the head from the notch position toward the extrusion side. It is characterized by.
As a fifth aspect of the present invention, in the plunger tip according to any one of the first, second, and third aspects, the notch portion is a linearly inclined notch portion that linearly inclines downward from the cut position toward the extrusion side. To do.
As a sixth aspect of the present invention, in the plunger tip according to any one of the first, second, and third aspects, the notch portion is a curved inclined notch 3 that is inclined downward in a curved shape from the cut position toward the pushing side. To do.

Since the plunger tip of the present invention is as described above, the following effects can be obtained.
The plunger tip according to claim 1 is provided with a notch portion in the spigot portion and formed in advance with a small diameter in anticipation of thermal expansion. Therefore, when the molten metal poured into the injection sleeve is filled into the cavity, the plunger tip Even if the inlay portion of the chip is heated and expanded by the heat of the molten metal, no galling or seizure occurs. As a result, a plunger tip having a long life can be provided.
In addition, the plunger tip of the present invention only forms a notch in the inlay portion of a commonly used plunger head, so that it is easy to improve and can be provided at low cost. The airtightness of the sleeve is increased, the inflow of secondary air is reduced, and the production of high-quality die-cast products is possible.

In addition to the features of the first aspect, the plunger tip of claim 2 has the cut position of the notch portion reaching the cooling chamber, so that at least the notch portion from the side surface of the molten metal in the cooling chamber to the cut position is cooled water. The cooling effect is received.
In addition to the features of claims 1 and 2, the plunger tip of claim 3 has only the depth of the notch cut into account for thermal expansion, so that the molten metal enters the gap with the injection sleeve. , Less individualized.
In addition to the features of claims 1, 2, and 3, the plunger tip according to claim 4 is a stepped notch,
In addition to the features of the first, second, and third aspects, the plunger tip according to the fifth and sixth aspects has a notch depth because the notch is a linearly inclined notch or the notch is a curved inclined notch. Is the maximum at the end surface of the head molten metal where the thermal expansion seems to be the largest.

  First, the structure of a horizontal die-casting device (cold chamber die-casting device) will be described with reference to FIG. The plunger head 2 is cooled by cooling water and the molten material supplied to the injection sleeve 4 is fed into the mold cavity C. The plunger head 2 is slidably inserted in the cylinder device (not shown). It is to be ejected.

  Next, the best mode of the plunger tip according to the present invention will be described with reference to FIG. 2. In the injection plunger 10 for extruding a molten metal toward a mold, the inlay portion 21 of the plunger head 2 constituting the injection plunger 10. In addition, the notched portion 5 in anticipation of thermal expansion is provided in advance, and the spigot portion 21 corresponds to a corner portion where the head outer peripheral surface 2a and the molten metal side end surface 2b intersect, that is, the front outer peripheral portion. As shown in FIG. 3, it is a stepped notch 51 that is notched parallel to the head outer peripheral surface 2a from the notch position toward the extrusion side, and the notch length H of the stepped notch 51 is 5 to 20 mm. The cutting position reaches the formation position of the cooling chamber 6 provided in the plunger head 2, and the cutting depth t is 1/1000 to 7/1000 of the head diameter R. 01-0 0.07 mm, and it is characterized in that the inlay portion does not come into contact with the injection sleeve 4 even if it is thermally expanded.

Since the plunger tip of the best form has the above structure, a stepped notch 51 is formed in advance in the spigot 21. At that time, it is important that the cutting position of the stepped notch 51 reaches the formation range of the cooling chamber 6 and has a biting length h between the cooling chamber molten metal side surface 6a and the cutting position. The depth t is a dimension that allows for the amount of thermal expansion, and is formed so that the molten metal cannot enter.
The plunger tip 1 of the present invention is screwed to the tip of the plunger rod 3 and inserted into the injection sleeve 4 and reciprocated by the cylinder device to fill the cavity with molten metal. At this time, although the spigot portion 21 of the plunger head 2 is suddenly heated and expanded by the heat of the molten metal, the spigot portion 21 has a small diameter in advance by the notch portion 5 in anticipation of thermal expansion. There is no contact with the sleeve 4 and no galling or wear occurs.

  The first embodiment of the plunger tip according to the present invention will be described in terms of differences from the best mode. As shown in FIG. 4, the plunger tip according to the first embodiment has a notch 5 directed from the cut position toward the extrusion side. This is a linearly inclined notch 52 that is inclined downward in a straight line. The cutting position of the linear inclined notch 52 reaches the formation range of the cooling chamber 6, and has a bite length h between the cooling chamber molten metal side surface 6a and the cutting position.

  The second embodiment of the plunger tip according to the present invention will be described in terms of differences from the best mode and the first embodiment. In the plunger tip according to the second embodiment, as shown in FIG. It is the curve inclination notch part 53 which inclines and inclines downward toward the extrusion side. The cut position of the curved inclined notch 53 reaches the formation range of the cooling chamber 6, and has a bite length h between the cooling chamber molten metal side surface 6a and the cut position.

The third embodiment of the plunger tip according to the present invention will be described in terms of differences from the above embodiment. The plunger tip according to the third embodiment is the same as that of the plunger head 2 having a head diameter R of 60 mm. A convex portion 22 projecting toward the extrusion side is formed in the central portion of 2b, and a notch portion 5 having a cut length H of 5 mm and a cut depth t of 0.01 mm from the head outer peripheral surface 2a is formed in the spigot portion 21. To form.
The formation of the convex portion 22 further reduces the thermal effect on the spigot portion 21.

A die-cast product was cast using the plunger tip of the present invention, and various heat treatments, strength tests, and the like were carried out. However, no surface swelling was observed in any of the products, and no harmful pores were found inside.
When the endurance test of the plunger tip of the present invention was performed, it was confirmed that it could be used for a long time as compared with the conventional plunger tip.

The cutting length H and the cutting depth t are not limited to those in the embodiment, and are formed in accordance with the head diameter R of the plunger head 2. For example, the cutting depth t is determined from the outer peripheral surface of the plunger head. It is also possible to form the cut length H from 0.01 to 0.08 mm to 5 to 15 mm from the cut position.
The range that can be adopted as the biting length h is 0.01 to 10 mm, preferably 0.1 to 10 mm, and the best range is 1 to 5 mm.
The relationship between the cutting length H and the cutting depth t is as shown in Table 1.

It is a schematic sectional drawing of the casting apparatus using the plunger tip concerning this invention. It is sectional drawing which shows the best form of the plunger chip | tip which concerns on this invention. It is an enlarged view which shows the 1st Example of the inlay part in this invention plunger tip. It is an enlarged view which shows 2nd Example of an inlay part. It is an enlarged view which shows 3rd Example of an inlay part. It is a temperature distribution figure which shows the cooling effect in an inlay part. It is a temperature distribution figure which shows conduction of the molten metal heat in an inlay part. It is principal part sectional drawing of the conventional plunger.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Injection plunger 1 Plunger tip 2 Plunger head, 2a Head outer peripheral surface, 2b, 12a Molten metal side end surface 21 Inlay part (front side outer peripheral part), 22 Convex part 3 Plunger rod 4 Injection sleeve 5 Notch part 51 Step shape Notch part, 52 Straight inclined notch part, 53 Curved inclined notch part 6 Cooling chamber, 6a Melt side face 7 Biscuit 8 Water supply port, 18 Drain port 9 Water pipe 11 Outer tip 12 Inner tip 13 Tip joint 14 Cooling water groove 16 Empty Part C Cavity h Cutting depth from the side of the cooling chamber molten metal to the cutting position H Cutting length t Cutting depth R Head diameter

Claims (6)

In the injection plunger (10) for extruding the molten metal toward the mold, a notch portion (5) in anticipation of thermal expansion is formed in the spigot portion (21) of the plunger head (2) constituting the injection plunger (10). ), And the inlay portion (2) does not come into contact with the injection sleeve (4) even when thermally expanded. 2. The plunger tip according to claim 1, wherein the cut position of the cutout portion (5) reaches the formation position of the cooling chamber (6) provided in the plunger head (2). The plunger tip according to claim 1 or 2, wherein the cut depth (t) of the notch (5) is 1/1000 to 7/1000 of the head diameter (R). The cutout portion (5) is a stepped cutout portion (51) cut out in parallel with the head outer peripheral surface (2a) from the cut position toward the extrusion side. 3. The plunger tip according to 3. The plunger tip according to claim 1, 2 or 3, wherein the notch (5) is a linearly inclined notch (52) inclined downwardly in a straight line from the notch position toward the extrusion side. . The plunger tip according to claim 1, 2 or 3, wherein the cutout portion (5) is a curved inclined cutout portion (53) inclined downward in a curved shape from the cut position toward the extrusion side. .

Images