JPH08114520A - Pressure measuring device and pressure casting method using pressure measuring device - Google Patents

Abstract

PURPOSE: To accurately and easily detect a change in pressure acting on molten metal in a metal mold cavity, make a structure comparatively simple, and facilitate manufacture and repair. CONSTITUTION: A deflection quantity transmitting bar 15 whose tip contacts with the reverse of a deflection plate part 13 arranged on a surface of a block 12, is provided, and the deflection quantity transmitting bar 15 is arranged inside the block 12 so as to be slowly movable in the axial direction, and a deflection quantity measuring plate 16 whose outside edge part reverse is supported by a holder in a rear part of the block 12, is arranged in a condition of being pressed against a rear end surface of the deflection quantity transmitting bar 15, and pressurizing casting is performed while measuring molten metal pressure by using a pressure measuring device where a displacement sensor 22 is arranged on the reverse side of the deflection quantity measuring plate 16 and a casting metal mold provided with this pressure measuring device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure measuring device and a pressure measuring device for measuring the pressure in a metal mold when a light metal alloy such as an aluminum alloy or a magnesium alloy is pressure-cast with a metal mold. The present invention relates to the pressure casting method used.

[0002]

2. Description of the Related Art Conventionally, when casting a light metal alloy such as an aluminum alloy, in general, in order to reduce shrinkage cavities, high pressure is applied from the time when the molten metal is cast into the mold until the solidification is completed. The method of continuing to pressurize has been adopted. In particular,
When high quality such as pressure resistance and high strength is required such as automobile parts, the above-mentioned high pressure casting method is often used. In this case, the magnitude of the pressure applied to the molten metal filling each part of the product greatly affects the quality of the product. For this reason, conventionally, the pressure of the molten metal was sometimes measured and used to control the casting conditions. In that case, a strain gauge was set on the back of the extrusion pin and the pressure of the molten metal was measured. Was.

As described above, when the strain gauge is set on the back of the extrusion pin, there is a problem that the measured value is not accurate due to the sliding resistance and frictional force of the extrusion pin with respect to the mold or the like.
This sliding resistance increases due to seizure, galling, etc. as casting is continued. Incidentally, JP-A-6-19054
When the pressure is applied in pulses as described in No. 3,
In particular, this issue is greatly highlighted. That is, when the pressure applied to the extrusion pin changes from a decrease to an increase, the extrusion pin remains stationary until the increase exceeds the static friction force. Conversely, when the pressure changes from increasing to decreasing, the push pin remains stationary until the amount of decrease exceeds the static friction force. Therefore, if the pressure fluctuation is smaller than the static frictional force, the push pin may not move at all and the pressure may not be measured in some cases.

Therefore, in order to eliminate such drawbacks, the applicant company has an in-mold pressure measuring device having a structure in which a part of the part of the mold facing the cavity is bent by a pressing force. Without receiving sliding resistance as in the past,
The pressure of the molten metal can be measured as accurately as possible.
And, for example, Japanese Patent Application No. 5-116014 and Japanese Patent Application No. 5-11
As described in the specification of No. 279511, a bending plate portion is provided on a part of the cavity side surface of the mold, and a bending amount transmitting rod whose tip is in contact with the back side of the central portion of the bending plate portion is arranged to bend the bending plate. For example, a disk-shaped flexure amount measuring plate is pressed against the rear end face of the amount transmitting rod, and the holder attached to the die supports the outer peripheral part of the flexure amount measuring plate. A strain gauge was attached to.

[0005]

However, in these methods and devices, since a disk-shaped bending amount measuring plate is used and the entire circumference of the bending amount measuring plate is supported by simple support, strain Measurement of strain and deflection with a gauge, and
Accompanying this, it has been relatively difficult to accurately obtain the pressure in the die that is calculated and obtained.

That is, in the conventional device, as shown schematically in FIG. 3, a strain gauge 31 is attached to the back side of the central portion of a disc-shaped flexure amount measuring plate 30. The rear end of the deflection amount transmission rod 32, whose tip is brought into contact with the back side of the portion of the mold which is not shown and which is made to bend by the applied pressure, contacts the central portion of the surface of the deflection amount measurement plate 30. Since they are in contact with each other, the flexure amount measuring plate 30 is curved, for example, as shown by the solid line in FIG. 3 or as shown by the two-dot chain line depending on the magnitude of the pressing force.

In this case, the bending amounts are δ ₁ and δ ₂ , respectively, and the distances from the corners of the supporting member 33 to the ends of the bending amount measuring plate 30 are a and b, respectively. It gets shorter. In this way, since the support point moves with the change in the amount of bending, the strain change is not linear. Further, since the flexure amount measuring plate 30 is a circular plate and is simply supported, the core may be displaced when the flexure amount measuring plate 30 is flexed, and thus a correct measured value may not be obtained in some cases.

Further, in the conventional one, the deflection amount transmission rod 32
Of the tip of the abutting part of the back surface of the flexible plate of the mold,
Also, the bending amount measuring plate 30 at the rear end of the bending amount transmission rod 32
Since the portion in contact with the flat surface has a predetermined width, when the bending plate portion of the mold or the bending amount measuring plate 30 bends, the bending amount transmitting rod 32 has a front end portion or a rear end portion. The contact position with and sometimes changed.

Further, for example, the point of action of the force acting on the flexible plate portion of the mold, which is the measuring portion facing the mold cavity, is
When the position of the bending amount transmitting rod 32 is different, the bending plate portion comes into contact with only one corner of the tip portion of the bending amount transmitting rod 32, which makes it difficult to perform accurate measurement. Due to various reasons as described above, it has been difficult or difficult to obtain an accurate in-mold pressure in the past.

Further, in the above-mentioned conventional example, the flexible plate portion itself is an embodiment in which it is completely integrated with the portion of the mold facing the cavity. Therefore, in this case, if a problem occurs in the flexible plate portion, the cavity surface itself of the mold must be repaired, which is inconvenient and requires many man-hours and costs.

[0011]

The present invention has been made to solve such a problem, and the tip of the pressure measuring device is in contact with the back surface of the flexible plate portion arranged on the surface of the block. The deflection amount transmission rod is arranged so that the deflection amount transmission rod can be finely moved in the axial direction inside the block, and the deflection amount measurement plate supporting the back surface of the outer edge portion at the rear part of the block is supported by the retainer. It was placed in a state of being pressed against the end face, and a displacement sensor was placed behind the flexure amount measurement plate. In addition, an iron plate was used as the bending amount measuring plate, and the bending amount measuring plate was supported by a holder via a spring arranged on the back surface of the bending amount measuring plate.

An eddy current sensor is used as the displacement sensor. In addition, the center of the front and rear ends of the bending amount transmission rod that is in contact with the back surface of the bending plate and the bending amount measuring plate is tapered. Furthermore, pressure casting was performed while measuring the molten metal pressure using a casting mold equipped with these pressure measuring devices.

[0013]

[Function] Since the pressure measuring device is provided separately from the mold by using the block, it can be manufactured separately and incorporated into the mold, and if a problem occurs in the pressure measuring device, this It is convenient because the pressure measuring device can be removed from the mold and repaired.

When a mold having the above-mentioned pressure measuring device mounted on the cavity surface is used and molten metal or the like is injected into the cavity of the mold to generate pressure in the cavity, the bending plate portion bends, and the bending amount transmitting rod. Is pressed, the bending amount measuring plate bends, and the amount of strain is measured by the position sensor. The amount of strain is calculated by a computer, etc., and the pressure inside the mold is determined.

As an example of the pressure measuring device, the deflection amount measuring plate is supported by a compression spring near the outer periphery on the rear side,
The fulcrum does not move, and the strain change appears linearly because it only moves linearly in the axial direction, and strain can be easily measured.

If an eddy current type sensor is used as the displacement sensor, the measurement can be performed easily and accurately. In addition, the eddy current sensor can be placed a little away from the deflection amount measuring plate, so it is not so affected by heat.

Further, if a bending amount transmitting rod having a tapered front end portion and a rear end portion is used, the contact point with the bending plate portion or the bending amount measuring plate may change or shift. No, there is always good measurement.

[0018]

1 and 2 show one embodiment of the present invention. FIG. 1 is a vertical sectional view of a pressure casting apparatus equipped with the pressure measuring apparatus of the present invention, and FIG. 2 is a longitudinal section of the pressure measuring apparatus. It is a side view. In a pressure casting apparatus also called a die casting machine or a squeeze casting machine shown in FIG. 1, 1 is a fixed mold, 2 is a movable mold that opens and closes in a horizontal direction, 3 is a cavity, and 1a and 2a are movable with the fixed mold 1 respectively. A nest fixed to the cavity 3 surface side of the mold 2 to form a part of the molds 1 and 2 and to form the outer peripheral surface of the cavity 3,
Reference numeral 4 is a casting sleeve, and 5 is a plunger tip that slides in the casting sleeve 4 and casts the molten metal in the casting sleeve 4 into the cavity 3.

Reference numeral 6 is a pressurizing pin for applying metal pressure to the molten metal cast in the cavity 3 in a cyclical and wavy manner, 7 is a hydraulic cylinder for operating the pressurizing pin 6, and 8 is a hydraulic cylinder 7. It is a bracket for attaching to a part of the fixed mold 1. A heat pipe 9 was implanted along the axis of the pressurizing pin 6 and a cooling water passage 10 was provided so that the thick portion of the cast product could be efficiently cooled. Reference numeral 11 is a pressure measuring device of the present invention, which will be described in detail later with reference to FIG.

When performing a casting operation using this apparatus,
Fill the mold cavity with the molten metal for casting, and apply a predetermined high pressure to the hydraulic cylinder that applies pressure to the molten metal in the cavity and a predetermined low pressure that is relatively small compared to this high pressure. By controlling and applying so as to alternately act periodically at short intervals, it is possible to control the solidified molten metal in the cavity from a predetermined high pressure and a predetermined low pressure that is relatively small compared to this high pressure. Is controlled so as to be applied periodically and alternately at short time intervals.
By feedback control, the fluctuation range and fluctuation frequency of the metal pressure are controlled to the intended values.

Then, when a relatively low pressure is applied immediately after a high pressure is applied, the heat transfer coefficient of the mold surface temporarily becomes small, and the latent heat generated during solidification is sufficiently removed from the mold surface. It is not heated, the melt temperature rises partially,
Crystal release and fusing release of dendrite branches occurs. Further, due to the pressure of a necessary and sufficient value that is applied in a wavy manner, the molten metal flows, which is also combined to promote crystal release and fusing release of dendrite branches.

As a result, columnar crystals are not formed, only equiaxed crystal zones are formed on the entire inner surface of the cast product, and solute elements are not segregated in the equiaxial crystal zones. Therefore, hot cracking does not occur, shrinkage cavities hardly occur, and a high-quality cast product with high strength and toughness can be reliably and easily obtained.

In the pressure measuring device 11 part shown in FIG. 2, 2a is a nest fitted in the movable mold 2, 3 is a cavity which is a molten metal casting space in the molds 1 and 2, and 12 is one of the molds 2. A block that is fitted from the rear side into a part of the cavity 3 side surface of the nest 2a that is a part, 13 is a block 12
Is a relatively thin circular flexible plate portion that is fitted in a part of the surface of the cavity 3 side, and a relatively deep hole 14 is provided behind the flexible plate portion 13 in a stepwise manner from the rear side. Has been. In addition, a large force is applied to the bending plate portion 13 by the cavity 3
Since it acts only from the side, it does not come out of the nest 2a.

On the back side of the central portion of the flexure plate portion 13, a round bar-shaped flexure amount transmission rod 15 is disposed so as to be in contact therewith, and a relatively thin flat plate circular iron plate is formed on the rear end surface of the flexure amount transmission rod 15. The bending amount measuring plate 16 made of steel was placed in a state where it was pressed or abutted. Considering that the contact point with the deflection amount measuring plate 16 and the measurement 0 point are delicately shifted due to the thermal expansion of the deflection amount transmitting rod 15, the deflection amount transmitting rod 15 has both a thermal expansion coefficient and a thermal conductivity. Small material, eg Si ₃ N ₄
Made in.

The deflection amount transmitting rod 15 does not have the same cross section over the entire length, but has a large diameter portion only in the portions near both ends in the block 12, and the other has a small diameter portion, and only this large diameter portion has a hole 18 in the block 12. It is slidably mounted on the inner surface of the to reduce sliding resistance.

Inside the hole 14 is a stepped cylindrical block 1
2 was loaded, and the block 12 was attached to the rear side of the insert 2a by the bolt 17 in a state where the outer peripheral portion of the front end surface thereof was in contact with the outer peripheral portion of the back surface of the flexible plate portion 13. The flexible plate portion 13 has a ring-shaped groove 1 from the back surface so that it can be easily bent.
3a is provided, and a circular comparatively thick portion 13 is provided at the center.
b is provided. However, the relatively thick portion 13b is configured so that the back surface does not contact the block 12. Such a shape is provided because the flexible plate portion 13 can be finely moved to easily measure the pressure change acting on the molten metal.

A thin hole 18 is provided at the center of the axis of the block 12 to guide the deflection amount transmission rod 15 slidably in the axial direction.
Was provided. The position of the bending amount transmitting rod 15 does not shift, and the tip of the bending amount transmitting rod 15 is always bent by the bending plate portion 1.
The thick portion 13b of 3 is in contact with the center position. The tip of the bending amount transmitting rod 15 is spherical, and even if a force is eccentrically applied to the bending plate 13, the tip is always at one point. On the other hand, the rear end portion of the deflection amount transmission rod 15 is formed into a conical shape or a spherical shape so that point contact is maintained in the same manner.

At the rear end of the relatively large circular hole 19 provided in the central portion of the block 12, a holding plate 20 is fixed with a bolt, and in the hole 19, the bending amount measuring plate 16 and the holding plate 20 are fixed. A compression spring 21 that supports the back surface of the outer edge portion of the flexure amount measuring plate 16 is provided between the 20 and 20 so that the flexure amount measuring plate 16 does not abut the block 12, and the flexure amount measuring plate 16 is slightly moved by the compression spring 21. Keep it pressed.

In the compression spring 21, the flexure amount measuring plate 16 is lightly pressed or brought into contact with the flexure amount transmitting rod 15 from the rear side to be positioned at a predetermined position, and the flexure amount transmitting rod 15 is extended so that the axial line is extended. Other members or devices, such as elastic members such as heat-resistant hard rubber, cylinders, etc., can be used as long as they extend in the direction.

A commercially available eddy current type high temperature displacement sensor 22 is provided at a central portion on the rear side of the flexure amount measuring plate 16 made of an iron plate, slightly apart from the flexure amount measuring plate 16 to change or output the eddy current. By measuring the change in the voltage, the subtle displacement of the flexure amount measuring plate 16 can be measured. Reference numeral 23 denotes a cylindrical portion provided integrally with the holding plate 20, and adjustment bottles 24 for finely adjusting the lateral position of the displacement sensor 22 are provided at, for example, 3 to 4 positions around the cylindrical portion 23.

The displacement sensor 22 is connected to a strain amount measuring device body (not shown). In this device, the flexure plate portion 13 is provided with a flexure amount measuring plate 16 via a flexure amount transmission rod 15.
Therefore, the strain amount of the bending amount measuring plate 16 corresponds to the strain amount of the bending plate portion 13 that bends in proportion to the magnitude of the pressure. In consideration of the thickness, shape and size of the bending plate portion 13 and the size of the bending amount measuring plate 16, the bending amount measuring plate 16
The pressure exerted on the flexible plate portion 13 can be converted from the strain amount of No. 3 and can always be accurately obtained immediately. The pressure obtained by the conversion can be displayed as a numerical value or can be displayed on a monitor in a graph to know the pressure fluctuation state.

When casting is performed, a metal pressing force is applied in a wavy manner to the molten metal immediately after filling the cavity 3. When carrying out the present invention, the best metal pressure, high pressure, low pressure, pressure fluctuation amplitude, pressure fluctuation frequency, etc. may vary depending on the type of alloy to be cast, the shape and size of the cast product, and the casting conditions. Different. However, the experimental results to date have shown that the pressure fluctuation amplitude range of the metal pressure applied in a wavy manner must exceed a certain value.

[0033] For example, 200 kg / cm ² or more preferably a 400 kg / cm ² or more average pressure, and ± 10 kg / cm ² or higher, preferably 20 kg / cm ² or more pressure fluctuation range, 2～500Hz preferably 5 to 20
A metal pressure having a pressure fluctuation frequency of 0 Hz is applied to the molten metal by the action of the hydraulic cylinder 7.

[0034]

According to the present invention, the pressure measuring device is provided with the deflection amount transmitting rod whose tip is in contact with the back surface of the deflecting plate portion disposed on the surface of the block, and the deflection amount transmitting rod is provided inside the block. A flexure amount measuring plate, which is provided so as to be finely movable in the axial direction and whose back surface is supported by a holder at the rear part of the block, is arranged in a state of being pressed against the rear end face of the flexure amount transmitting rod, and a displacement sensor is provided on the back side of the flexure amount measuring plate. Since the structure is arranged, it can be manufactured separately from the mold, and can be easily attached to and removed from the mold, and can be easily repaired. Also, the structure can be relatively simple.

Further, since an iron plate is used as the bending amount measuring plate, the bending amount measuring plate is supported by a holder via a spring arranged on the back surface of the bending amount measuring plate, and an eddy current sensor is used as the displacement sensor. When the bending amount measuring plate is pushed by the bending amount transmission rod,
The strain change appears linearly, and the amount of bending, and the pressure and pressure fluctuation in the mold can be measured and calculated reliably and easily. In addition, since the tip and the rear end of the deflection amount transmission rod are tapered, the contact point with the deflection plate portion and the deflection amount measurement plate does not change or deviate, and good measurement is always performed. Can be done.

If such a pressure measuring device is cast by using a die mounted on the cavity surface of the die, the pressure in the die and the fluctuation of the pressure can be obtained as a comprehensive result of the above-mentioned various advantages. ， Always can be obtained easily and accurately. For example, even when a large pressure and a small pressure of several hundred kg / cm ² alternately act on the molten metal in the cavity in a pulse shape at about 5 to 500 Hz, there is no part where resistance is generated. Since it responds quickly, the pressure fluctuation can be detected reliably and easily.

Further, since pressure casting is carried out while measuring the molten metal pressure using this pressure measuring device, the molten metal pressure which is constantly changing is measured appropriately, and the molten metal pressure is applied while feedback control is performed based on the measured pressure. The pressure can be varied under good conditions.

If the applied pressure of the molten metal is changed in a pulsed manner at an extremely short cycle, high pressure and low pressure are added to the molten metal in the cavity periodically and in a wavy manner, so that the molten metal is pressed against the mold surface. The degree of heat changes to strong and weak, and as a result, the heat transfer coefficient when heat is transferred from the surface of the molten metal to the surface of the mold changes periodically, and the amount of heat removed to the mold changes periodically.

When a relatively low pressure is applied immediately after a high pressure is applied, the heat transfer coefficient of the mold surface temporarily becomes small, and the latent heat generated during solidification is sufficiently removed from the mold surface. It is not heated and the temperature of the melt partially rises, causing crystal liberation and fusing desorption of dendrite branches. Further, due to the pressure of a necessary and sufficient value that is applied in a wavy manner, the molten metal flows, which is also combined to promote crystal release and fusing release of dendrite branches. At this time, as for the solidification form of the molten metal, nuclei are generated not only on the surface of the molten metal facing the cavity surface of the mold but also in the molten metal, and solidification progresses.
It becomes a so-called massy type solidification morphology in which equiaxed crystals are formed.

As a result, columnar crystals are not formed, only equiaxed crystal zones are formed on the entire inner surface of the cast product, and solute elements are not segregated in the equiaxial crystal zones. Therefore, hot cracking does not occur, shrinkage cavities hardly occur, and a high-quality cast product with high strength and toughness can be reliably and easily obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment including a device of the present invention.

FIG. 2 is an apparatus showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating the operation of the conventional technique.

[Explanation of symbols]

 1 Fixed Mold 2 Movable Molds 1a, 2a Nesting 3 Cavity 4 Casting Sleeve 5 Plunger Chip 6 Pressurizing Pin 7 Hydraulic Cylinder 11 Pressure Measuring Device 12 Block 13 Bending Plate Part 15, 32 Bending Amount Transmission Rod 16, 30 Bending Amount Measuring plate 21 Compression spring 22 Eddy current displacement sensor 31 Strain gauge

Claims (5)

[Claims] 1. A flexure amount transmission rod, the tip of which is in contact with the back surface of a flexure plate portion provided on the front surface of the block, is provided so that the flexure amount transmission rod can be finely moved in the axial direction inside the block. A pressure measuring device in which a flexure amount measuring plate, in which the back surface of the outer edge portion is supported by a holder in the rear part, is arranged while being pressed against the rear end face of the flexure amount transmitting rod, and a displacement sensor is arranged on the back side of the flexure amount measuring plate. 2. The pressure measuring device according to claim 1, wherein an iron plate is used as the bending amount measuring plate, and the bending amount measuring plate is supported by a holder via a spring arranged on the back surface of the bending amount measuring plate. 3. The pressure measuring device according to claim 1 or 2, wherein an eddy current sensor is used as the displacement sensor. 4. The taper according to claim 1, wherein the back surface of the central portion of the flexible plate portion and the central portion of the front end and the rear end of the flexible amount transmission rod in contact with the flexible amount measuring plate are tapered. Pressure measuring device. 5. A flexure amount transmission rod whose tip is in contact with the back surface of a flexure plate portion provided on the front surface of the block is provided, and the flexure amount transmission rod is provided inside the block so as to be finely movable in the axial direction. A pressure measuring device, in which a bending amount measuring plate supporting the back surface of the outer edge portion by a holder in the rear part is arranged in a state of being pressed against the rear end face of the bending amount transmitting rod, and a displacement sensor is arranged on the back surface of the bending amount measuring plate, Embedded in the stepped hole provided on the cavity side of the mold, so that the surface of the block of the pressure measuring device constitutes a part of the surface of the cavity of the mold, and a casting mold equipped with this pressure measuring device is used. A pressure casting method that uses a pressure measuring device that measures the molten metal pressure while performing pressure casting.