JPH0750045Y2 - Molten metal injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a molten metal injection pump for injecting molten metal, which can be used in a hot chamber type die casting machine or the like.

[Background technology]

Conventionally, various types are used for die casting, but for example, in a hot chamber type die casting machine, a metal stored in advance in a molten state is injected into a mold by an injection pump.

As such a molten metal injection pump, for example,
A plunger type injection pump 1 as shown in the figure is used.

In FIG. 3, an injection pump 1 is provided with a plunger sleeve 3 into which a plunger 2 is inserted and fitted, and the plunger 2 is always in close contact with the inner periphery of the sleeve 3 and is in a tightly sealed state. It is pushed back and forth to the limit. A closed pressure chamber 4 is formed below the plunger 3,
The pressurizing chamber 4 is communicated with a mold or the like (not shown) through a flow path 5 for injection. On the other hand, a groove-shaped introduction passage 6 is formed on the inner peripheral surface of the plunger sleeve 3, and the introduction passage 6 is opened when the plunger 2 is at the backward limit so that the introduction passage 6 is introduced into the pressurizing chamber 4 from the upper molten metal reservoir 7. Although molten metal is introduced, it is closed when the plunger 2 moves forward to maintain the pressure chamber 4 in a sealed state. Therefore, the injection pump 1 can repeatedly perform the operation of pressurizing the molten metal in the pressurizing chamber 4 supplied when the plunger 2 advances and retracts and injecting it to the flow path 5 by forward movement.

Further, as the plunger type injection pump 1, a structure as shown in FIG. 4 is also used.

In FIG. 4, a piston ring 8 is fitted to the outer periphery of the lower end of the plunger 2 to improve the sealing performance between the piston 3 and the sleeve 3, thereby improving the sealing performance of the pressurizing chamber 4. In addition, the introduction path 6 is a pipeline using the thickness of the sleeve 3,
By arranging one end thereof at an appropriate position on the inner circumference of the sleeve 3, the plunger 2 is configured to be opened when it is in the retracted limit.

By the way, there is a problem that the high temperature molten metal handled by the injection pump 1 has a high erosion property with respect to a metal part which comes into contact with the injection pump 1. Therefore, a material having a high corrosion resistance such as fine ceramics is appropriately used for the plunger sleeve 3 and the like.

Further, in the injection pump 1, the amount of leakage from the gap between the plunger 2 and the sleeve 3 is said to be proportional to the cube of the gap size, and the gap between the plunger 2 and the sleeve 3 is about 40 to 60 μm at any position. It is desirable to fit.
Therefore, the outer periphery of the plunger 2 and the inner periphery of the sleeve 3 are precision-finished by grinding over the entire stroke of sliding contact.

[Problems to be solved by the device]

However, in the conventional injection pump 1 described above, it is difficult to finish the inner circumference of the plunger sleeve 3 over a long distance with high accuracy and uniformity, and there is a problem that the manufacturing is not easy.

In particular, fine ceramic materials are difficult to be precision finished by grinding, and it is extremely difficult to precisely finish the inner circumference over a long distance like the plunger sleeve 3 described above.

Further, since the tip end of the plunger 2 is in sliding contact with the inner circumference of the plunger sleeve 3, there is a problem that the gap tends to widen due to damage or wear due to one-sided contact and the life cannot be extended.

Therefore, the total length La of the plunger sleeve 3 is shortened, but if the length Lb with which the plunger 2 is fitted in the backward limit is shortened, the plunger 3 is not held sufficiently by the sleeve 3 and two points are required. As shown by the chain line, the plunger 2 tends to tilt and cause one-sided contact. In such a case, there is a problem that each contact portion is likely to be worn or chipped and the injection operation is not smooth.

An object of the present invention is to provide a molten metal injection pump that is easy to manufacture, has less wear, and operates smoothly.

[Means for Solving the Problems]

The present invention provides a pressurizing chamber whose inside is pressurized by advancing and retracting the plunger tip inserted from the base end side, and the inner circumference is adjacent to the base end side of the pressurizing chamber and the inner circumference is always predetermined with the outer circumference of the plunger tip. It is characterized in that a guide sleeve which is slidably contacted over the length is provided.

Here, the sliding contact length between the inner circumference of the guide sleeve and the outer circumference of the plunger tip may be such that the plunger tip can be slidably guided and maintained at a regular axis. Also,
In order to maintain a predetermined sliding contact length, it is desirable that the plunger tip is always fitted in the guide sleeve, and the tip of the plunger tip is always exposed from the end of the guide sleeve and remains in the pressurizing chamber. .

[Action]

In the present invention, the pressurization chamber is pressurized by projecting the plunger tip from the guide sleeve toward the pressure chamber.

At this time, the plunger tip is always slid in contact with the guide sleeve for a predetermined length and guided to the desired state, so that the plunger tip can be securely prevented from tilting or coming into contact with the guide sleeve, smoothing the operation and reducing wear. It is possible to prolong the service life.

Also, since the pressurizing chamber is sealed between the plunger tip and the guide sleeve, the guide sleeve that requires precision finishing on the inner circumference can be sufficiently shorter than the conventional plunger sleeve, and Since it is a finish, it is easy even if it is long. Therefore, it becomes possible to easily carry out the production, and thereby the above-mentioned object is achieved.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, an injection pump 10 is installed in a hot chamber type die casting machine and injects molten metal from a hot chamber (not shown) into a die (not shown).

The injection pump 10 has a molten metal reservoir 11 for temporarily storing the molten metal to be injected, and the molten metal from the hot chamber is always automatically supplied to a certain level in the inside thereof. A cavity 12A for a pressure chamber is bored in the bottom surface of the molten metal reservoir 11, and a cylindrical guide sleeve 13 is coaxially fitted and fixed to the upper end opening thereof. A rod-shaped plunger tip 14 is coaxially inserted into the guide sleeve 13 from above, and its tip end side is exposed at the lower end side of the guide sleeve 13. Here, the pressurizing chamber cavity 12A is closed below the guide sleeve 13 by the tip of the plunger tip 14, and the pressurizing chamber 12 is formed by this portion.

The pressurizing chamber 12 has an inner diameter D2 over the depth L2, and the plunger tip 14 has a constant outer diameter D4 over the length L4 from the tip. Here, the inner diameter D2 of the pressurizing chamber 12 is the plunger tip 14
Is larger than the outer diameter D4 of the pressure chamber 12 and the depth L2 of the inner diameter D2 of the pressurizing chamber 12 is the maximum protruding length (stroke) of the plunger tip 14.
It is formed larger than L1, and the outer periphery and the tip of the plunger tip 14 do not contact the inner periphery of the pressurizing chamber 12.

The guide sleeve 13 has an inner diameter D3 over its entire length, and this inner diameter D3 is set to be substantially equal to the outer diameter D4 of the plunger tip 14. Here, the inner surface of the guide sleeve 13 and the outer surface of the plunger tip 14 are precisely finished so that the mutual clearance is about 10 to 20 μm.
Is fitted in the guide sleeve 13 so as to be slidable in the axial direction and uniformly at any position. The pressurizing chamber 12 is hermetically sealed by the sealing property of the fitting portion between the plunger tip 14 and the guide sleeve 13.

The plunger tip 14 is axially driven by a drive device (not shown), and is movable back and forth between the backward limit shown by the solid line and the forward limit shown by the alternate long and short dash line. At this time, stroke
L1 is the length L4 of the plunger tip 14 and the guide sleeve
Based on the length L3 of L13, L1 = L4-L3 is established, and the fitting between the plunger tip 14 and the guide sleeve 13 is constantly maintained over the entire length L3 of the guide sleeve 13.

A central hole is formed along the central axis on the tip end surface of the plunger tip 14.
15 is opened, and a side surface hole 16 is opened from the side surface of the plunger tip 14 so as to communicate with the center hole 15.
An introduction path 17 is formed by 15, 16. Here, the side surface hole 16 is located at a position above the upper end of the guide sleeve 13 when the plunger tip 14 is in the retracted limit, and the pressurizing chamber 12 is communicated with the molten metal reservoir 11 through the introduction path 17 in the retracted limit. Molten metal is introduced into. However, when the plunger tip 14 is projected, the side surface hole 16 is covered with the guide sleeve 13 or opened into the pressurizing chamber 12, and the pressurizing chamber 12 is maintained in a sealed state.

The bottom surface of the pressurizing chamber 12 is formed in a conical shape, and a flow path 18 connected to a mold (not shown) is formed in that portion. here,
When the tip side of the plunger tip 14 is projected from the guide sleeve 13, the volume of the pressure chamber 12 is reduced according to the amount of protrusion, and the molten metal inside is pressurized and injected from the flow path 18 into the mold. It

In the present embodiment configured as described above, by moving the plunger tip 14 forward and backward, the molten metal is supplied and filled from the molten metal reservoir 11 to the pressurizing chamber from the introduction path 16 at the backward end thereof, and the plunger tip 14 is moved forward. The molten metal pressurized inside the pressurizing chamber 12 as the protrusion reaches the limit
Is injected into the mold from.

According to the present embodiment as described above, there are the following effects.

That is, the plunger tip 14 is always fitted and held in the guide sleeve 13 with a constant clearance over the length L3.

Therefore, the axis of the plunger tip 14 in the advancing / retreating direction can be accurately maintained at any position, and the tilt and the one-sided contact and the malfunctions and wear defects resulting from these can be significantly reduced or eliminated.

Moreover, the fitting seal of the plunger tip 14 and the guide sleeve 13 over the constant length L3 can always ensure the airtightness in the pressurizing chamber 12, and can maintain the injection performance by pressurization high.

Furthermore, the plunger tip 14 is in sliding contact only with the guide sleeve 13, and wear itself due to normal operation is also reduced.

Especially, the tip of the plunger tip 14 is always a guide sleeve.
It is in a state of protruding from the lower end of the guide sleeve 13, and the inner circumference of the guide sleeve 13 does not come into sliding contact with the corners or the like of the tip of the plunger tip 14 that is easily worn.

The inner diameter D2 of the pressurizing chamber 12 is the outer diameter D4 of the plunger tip 14.
It is larger and the plunger tip 14 does not come into contact with the inside of the pressurizing chamber 12 at any position. Therefore, the pressure chamber 12
The inner circumference of is not worn as the plunger tip 14 moves back and forth.

Further, the guide sleeve 13 only needs to have a length L3 necessary for holding the sliding contact, and may be sufficiently shorter than a conventional cylinder sleeve having a length longer than the stroke. For this reason,
It is possible to shorten the precision finishing of the inner circumference, and it is also easy to perform high precision finishing with excellent linearity, which greatly simplifies manufacturing.

On the other hand, the plunger tip 14 requires precision finishing over the length L4, which is the stroke L1 plus the sliding contact length L3, but since this is machining of the outer circumference, it is relatively easy even for long distances. Can be finished, and manufacturing can be facilitated as a whole.

Therefore, according to the injection pump 10 of the present embodiment, it is possible to easily manufacture a high-accuracy pump, to perform the operation smoothly and reliably, and to reduce wear during normal operation and eliminate defective operation such as one-sided contact. Can significantly extend the life.

The present invention is not limited to the above embodiment,
The following modifications are also included.

That is, the material, size, detailed shape, etc. of each part in the above-described embodiment may be appropriately changed in carrying out, and in short, the plunger tip 14 is fitted only by the guide sleeve 13 continuously arranged on the inlet side of the pressurizing chamber 12. Any setting is possible as long as it can be held and the sliding contact of the portion can be secured for a certain length.

Further, as in the other embodiment shown in FIG. 2, the piston ring 21 may be used to secure the sealing property between the plunger tip 14 and the guide sleeve 13. In FIG. 2, the injection pump 20 is basically the injection pump of the above embodiment.
Same as 10, but with inner diameter of guide sleeve 13
D3 is set to be slightly larger than the outer diameter D4 of the plunger tip 14, and an inside piston ring 21 is triple fitted around the lower end of the inner circumference of the guide sleeve 13. In such other embodiment as well, the same effect as in the above embodiment can be obtained, and the sealability of the pressurizing chamber 12 can be enhanced by the piston ring 21. Further, by using the piston ring 21, it is possible to increase the clearance between the guide sleeve 13 and the plunger tip 14, simplify the finishing, and further facilitate the manufacturing.

On the other hand, the structure for introducing the molten metal into the pressurizing chamber 12 is not limited to the introducing passage 17 described above. That is, in the injection pump 20 of another embodiment shown in FIG. 2, a groove 22 is formed on the outer periphery of the plunger tip 14 from the front end face upward, and on the inner periphery of the guide sleeve 13 downward from the upper end face. A groove 23 is formed toward. These grooves 22 and 23 partially overlap with each other and communicate with each other when the plunger tip 14 is in the retracted limit, thereby forming an introduction path 24. With such a configuration, it is sufficient to process the grooves 22 and 23, which facilitates the manufacturing.

[Effect of device]

As described above, according to the present invention, manufacturing can be facilitated by reducing precision processing, wear can be reduced by shortening the sliding contact distance, and the operation can be smoothed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing another embodiment of the present invention, FIG. 3 is a sectional view showing a conventional example, and FIG. 4 is another conventional example. FIG. 10, 20 ... Injection pump, 12 ... Pressurizing chamber, 13 ... Guide sleeve, 14 ... Plunger tip.

Claims (2)

[Scope of utility model registration request] 1. A molten metal injection pump having a pressurizing chamber whose interior is pressurized by advancing and retracting a plunger tip inserted from the base end side, the inner periphery being adjacent to the base end side of the pressurizing chamber. Is provided with a guide sleeve which is always in sliding contact with the outer periphery of the plunger tip over a predetermined length. 2. In the claim 1 of the utility model registration claim,
The molten metal injection pump according to claim 1, wherein the guide sleeve has an inside piston ring on its inner circumference.