CA1191327A - Vertical type pressure casting method - Google Patents
Vertical type pressure casting methodInfo
- Publication number
- CA1191327A CA1191327A CA000403386A CA403386A CA1191327A CA 1191327 A CA1191327 A CA 1191327A CA 000403386 A CA000403386 A CA 000403386A CA 403386 A CA403386 A CA 403386A CA 1191327 A CA1191327 A CA 1191327A
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- Canada
- Prior art keywords
- melt
- gates
- cavities
- plunger tip
- tip
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
ABSTRACT OF THE DISCLOSURE
The gist of the construction, casting conditions and program for a casting method capable of attaining the above object of the present invention resides in a method compris-ing the steps of closing gates with a counter tip after lower and upper molds heated to a predetermined temperature have been clamped, pouring melt into a sleeve in which a plunger tip is lifted a predetermined distance, lowering the plunger tip while displacing the counter tip to a predetermined position to open the gates, which are formed such that the ratio of the volume of products to the cross-sectional area of the gates is 20-40 (the volume of products (cm3)/cross-sectional area of gates (cm2) = 20-40), to allow the melt to flow into cavities via the gates by the force of gravity alone with the plunger tip reaching the upper surface of the melt the moment a percentage of the melt placed in the cavities has reached a value between 20 and 70%, and pressure-filling the cavities with the melt by the plunger tip with the melt passing through the gates at 0.4-0.8 m/sec.
The gist of the construction, casting conditions and program for a casting method capable of attaining the above object of the present invention resides in a method compris-ing the steps of closing gates with a counter tip after lower and upper molds heated to a predetermined temperature have been clamped, pouring melt into a sleeve in which a plunger tip is lifted a predetermined distance, lowering the plunger tip while displacing the counter tip to a predetermined position to open the gates, which are formed such that the ratio of the volume of products to the cross-sectional area of the gates is 20-40 (the volume of products (cm3)/cross-sectional area of gates (cm2) = 20-40), to allow the melt to flow into cavities via the gates by the force of gravity alone with the plunger tip reaching the upper surface of the melt the moment a percentage of the melt placed in the cavities has reached a value between 20 and 70%, and pressure-filling the cavities with the melt by the plunger tip with the melt passing through the gates at 0.4-0.8 m/sec.
Description
3;"~
VERTICA:I:. TYPE PRESSURE C~STING M~T~IOD
~ACKGROUND OF Tl-3E INVENTION
1. Field of the Invention The present invention relates to a vertical type pressure casting method used for accurately casting aluminum alloy products, comprising the steps of closing gates communicating with the cavities of clamped molds with a counter-tip, pouring melt into the portion of the interior of a sleeve which is between the counter-tip and a lifted.plunger tip, displacing the counter-tip to open the gates and allow the mel-t to flow into the cavities by the force of gravity, and thereafter pressure-filling the cavities with the melt using the plunger tip, characterized in that a casting program is used, by which program the gates are opened by the counter-tip after the plunger tip has started moving downward, and the speed of the plunger tip during the period of time from the commencement of i-ts downward movement to -the opening of the gates is set to a speed between the speed at which the plunger tip reaches the melt in the sleeve when or before the gates are opened by the counter--tip, and the speed at which the plunger tip reaches the melt at the time the melt stops flowing into the cavities by the force of gravi-ty alone.
In a preferred form the present invention is a vertical type pressure casting me-thod comprising the steps of first lowering a plunger tip, subsequently dis-placing a counter-tip before the plunger ti.p reaches the melt in the sleeve to open the gates to the cavities and allow the melt to flaw into the cavities by the force of gravity, and thereafter pressurizing the melt to fill the - 1- ~,.
vtd/~
cavit.L(s, the me.lt belnq thus .injecte(l Lnto the caviti.es calmly and contirluo;ly at a Low rate to prevent gas frorn being sucked there:Ln, the cross-sectional area of the gates being set so that the ratio oE the volume of the pro~ucts to the cross-sectional area of the gates - la -vtd/~
~.~Jg ~.3J.. .~
is 2()-40 (~ol.ul~ oEpr~1~1cts (cm )/c:rocls~cect:ion~l:l.c-recloEclat~s (~n2) = 20-~10), the speed o:~ the p:Lunger tip and the length of t~
between commencing the downward movement of the plunger tip and opening the gates being set to an op-timum level determined in relation to the tempexatu.res of the molds and melt, a percentage of the melt to be ~ed illtO the cavities by the force of gravity before the plunger tip reaches the melt in the sleeve being set to 20-70, if the plunger tip does not move the percentage of the melt which is to Elow into the cavities by the force of gravity alone being set to not less than 30%, the speed of the melt through the gates when pressure-filling the cavities with the plunger tip being set to 0.4-0.8 m/sec.
VERTICA:I:. TYPE PRESSURE C~STING M~T~IOD
~ACKGROUND OF Tl-3E INVENTION
1. Field of the Invention The present invention relates to a vertical type pressure casting method used for accurately casting aluminum alloy products, comprising the steps of closing gates communicating with the cavities of clamped molds with a counter-tip, pouring melt into the portion of the interior of a sleeve which is between the counter-tip and a lifted.plunger tip, displacing the counter-tip to open the gates and allow the mel-t to flow into the cavities by the force of gravity, and thereafter pressure-filling the cavities with the melt using the plunger tip, characterized in that a casting program is used, by which program the gates are opened by the counter-tip after the plunger tip has started moving downward, and the speed of the plunger tip during the period of time from the commencement of i-ts downward movement to -the opening of the gates is set to a speed between the speed at which the plunger tip reaches the melt in the sleeve when or before the gates are opened by the counter--tip, and the speed at which the plunger tip reaches the melt at the time the melt stops flowing into the cavities by the force of gravi-ty alone.
In a preferred form the present invention is a vertical type pressure casting me-thod comprising the steps of first lowering a plunger tip, subsequently dis-placing a counter-tip before the plunger ti.p reaches the melt in the sleeve to open the gates to the cavities and allow the melt to flaw into the cavities by the force of gravity, and thereafter pressurizing the melt to fill the - 1- ~,.
vtd/~
cavit.L(s, the me.lt belnq thus .injecte(l Lnto the caviti.es calmly and contirluo;ly at a Low rate to prevent gas frorn being sucked there:Ln, the cross-sectional area of the gates being set so that the ratio oE the volume of the pro~ucts to the cross-sectional area of the gates - la -vtd/~
~.~Jg ~.3J.. .~
is 2()-40 (~ol.ul~ oEpr~1~1cts (cm )/c:rocls~cect:ion~l:l.c-recloEclat~s (~n2) = 20-~10), the speed o:~ the p:Lunger tip and the length of t~
between commencing the downward movement of the plunger tip and opening the gates being set to an op-timum level determined in relation to the tempexatu.res of the molds and melt, a percentage of the melt to be ~ed illtO the cavities by the force of gravity before the plunger tip reaches the melt in the sleeve being set to 20-70, if the plunger tip does not move the percentage of the melt which is to Elow into the cavities by the force of gravity alone being set to not less than 30%, the speed of the melt through the gates when pressure-filling the cavities with the plunger tip being set to 0.4-0.8 m/sec.
2. Description of the Prior Art As is generally known, there are various kinds of cast products. Among these, cast products of a light.alloy such as aluminum alloy have generally been manufactured by gravit~ casting, low-pressure casting and pressure die casting.
Howevex~ because of the following problems, these casting methods do not yielcl high quality cast products and the productivity cannot be improved . In gravity casting and low-pressure casting, the melt is not forcibly pressurized, so that so-called shrinkage holes occur in it in the solidi~ying step. Consequently, ~- 2 --~' ms/~ ~
sound products cannot be obtained. Mor~over, the so].idif~iny rate in these cast:ing methods is low, decreasing the produc-tivity.
Inpressure die casting, the sleeve-charging ~ercen-tage is 50-70, and, moreover, the melt is introduced into cavities under pressure at a high rate. Accordingly, the gas in certain portions of the passage for the melt, such as gates, and in the cavities is liable to mix with the melt, decreasing the reliability of the quality of the products.
With a view to eliminating the above-mentioned incon-veniences, a vertical type die casting method has been developed, which has a sleeve-charging percentage of 100, and in which the melt is pressurized without mixing with gas in the gates and cavities. Howèver, this casting method also has some pro~lems which have not yet been completely solved with respect to sof-t materials for obtaininc3 high-quality products, namely the casting conditions and a casting program in relation to the casting mechanism. Thus, the advantages of this casting method cannot be utilized effect-ively.
SUMMARY OF TH~ INVENTION
An object of the present invention is to provide an excellent vertical type pressure casting me-thod, which has been developed in view of the problems with the above-mentioned vertical type casting method, which was developed 1~;
'7 to supersede the existing casting me-thocl usincJ metal molds, and which has various advantages bu-t does not give full play to its functions. The casting condi-tions include -the speed of the plunger and the -temperatures of the molds and melt, and the desicJn conditions include the percentage of melt to be introduced into cavities by -the force of gravity, and the cross-sectional area of gates in the Method according to the presen-t invention being set to levels in optimum ranges with respec-t -to one another, whereby highly reliable high-quality products can be cast.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings show an embodiment of the present invention, wherein:
Fig. 1 is a schematic diagrarn o.f a vertical type pres-sure casting appara-tus;
Figs. 2, 3 and 4 illustrate the process for pouring the melt through gates into cavities;
Fig. 5 is a diagram illustrating the rela-tion between the speed of downward movement of the plunger tip and the length of a period of time from the commencement of downward movement of the plunge~ unit and the opening of the gates by a counter-tip; and Fig. 6 is a graph showing percentages of inferior products in the embodiment and a conventional method.
'7 DETAILED DESC~IPri`ION OF T}lr' P~-`FERRED ~MBODIMENT
An embodiment of the present invention will now be described with reference to the accompanying drawings.
Fig. 1 shows h vertical type pressure casting apparatus used in the method according to the present invention. A
lower mold 1 and an upper mold 2 are clamped together to form cavities 3, 3. Gates 4 for the cavities 3, 3 face the interior of a sleeve 5. A counter-tip 7 connected to a hydraulic cylinder 6, and a plunger tip 9 connected to a hydraulic cylinder 8 are provided opposing each other in lower and upper positions, respectively, in the sleeve 5 such that the counter~tip 7 and plunger tip 9 can be moved up and down therein. A solenoid in a changer-over valve 10 connected to hydraulic cylinder 6 is controlled by a limit switch 12 with respect to a dog provided on the rod of plunger tip 9.
The melt 15 is poured from a melt inlet port 13 into the sleeve 5 by a ladle 14.
The above apparatus is designed so that the ratio of the volume (cm ) of the prod~lct to-the cross~ n~l area (cm2) of the gates 4, which is one of the construction parameters of the apparatus, is 20-40.
The operational conditions and program for the present invention to be practiced by using the apparatus of this construction are set to attain the following: The plunger tip 9 is moved downward to lower the counter-tip 7 through ~13~ 1'J~J
-the dog 11 and limit switch 12. The rela-tion between the speed V m/sec at which the plunger ti.p 9 moves downward and the length of -ti.rme T sec from -the commencement of the downward movemen-t of -the plunger -tip 9 to the openi,ng of the gates ~ by the counter tip 7, is set to an optimal value with reference -to the information shown in Fig. 5. Namely, the speed, at which the plunger tip moves down is set to a level between the upper limit level in an upper limit speed curve Rl, above which the plunger tip 9 moves down too East and reaches the upper surface of the melt 15 in the sleeve 5 to start the pressure-filling operation before the gates 4 have been opened by the counter tip 7, and a lower limit level in a lower limit speed curve R2, above which the plunger tip ~ reaches the upper surface of the melt 15 in the sleeve 5 after the gates ~ have been fully openecl by the counter tip 7 allowing the melt 15 to flow into the cavities by the force o~ gravity until the flow of melt has stopped, whereby -the melt 15 can be fed to the cavities calmly and continuously at a low rate.
According to the experimental resul.ts, the percenta~e distribution of acceptable cast products with respect to the whole number of cast products obtained under different conditions is as shown in the data in Fig. 5.
A: not less than 90% B: 50-90%
C: 20-50% D: not more than 20%
This relation between the speed of the plunger tip and the leng-th o~ a period of time between the cor~encement of the downward movement of the plunger and the opening of the gates can also be set differently by varying not only the cross-sectional area of the gates but also the temperatures of the molds and melt.
After the cross-sectional area of the gates and the temperatures of the molds and melt have been determined, the percentage of the melt to be fed into the cavities by the force of gravity before the plunger tip 9 reaches the upper surface of the melt 15 in the sleeve 5 is set to 20-70, and the speed of the melt through the gates during the feeding of the melt to the cavities by the force of gravi-ty to not less than 0.1 m/sec with the speed of the melt through the gates when pressure~filling the cavities using the plunger tip 9 set to 0.4-0.8 m/sec.
The molds are clamped as shown in Fig. 1 with the castiny apparatus set in accordance with the above-mentioned casting conditions and prog-~am, and the hydraulic cylinder 6 is actuated to close the gates 4 with the counter--tip 4.
The hydraulic cylinder 8 is then actuated to set the plunger tip 9 to an initial attitude position~
A predetermined amount of melt 15 is then poured from a melt inlet port 13 into the sleeve 5, and a button for a control unit (not shown) is pressed to actuate the hydraulic cylinder 8 to start the casting operation in accordance with the cas-ting conclitions and program referred to above.
First, when the plunger tlp 9 starts being moved downward a-t a predetermined speed with the dog 11 coming into contact with the limi-t switch 12, the counter-tip 7 is moved downward at a predetermined time by operation of the change-over valve 10 before the plunger tip 9 has reached the upper surface of the melt 15 in the sleeve 5 as shown in Fig. 2, in accordance with the relation between the set speed and -time shown in Fig. 5, to open the gates 4. The melt 15 then starts flowing from the gates 4 into the cavities 3 by the force of gravity.
After a predetermined period of time has passed, the plunger -tip 9 reaches the upper surface of -the melt 15 (which is, of course, flowing in-to the cavi.ties by the force of gravity) in the sleeve 5. At this time, the percentage of the melt placed in the cavities is 20-70 as mentioned above.
The melt-feedlng by the force of gravity is then changed to pressure-filling as shown in Fig. 4. The speed of the melt through the gates during pressure-filling by the plunyer tip 9 is set to 0.4-0.8 m/sec as mentioned above.
Thus, in the casting operation as a whole according to the present invention, the melt 15 in the sleeve 5 is fed into the cavities by its own weight, i.e. by the force of gravi-ty, in the initial s-tage, and under pressure by ''7 the plunger tip 9 be:Eore -the gravity feeding operation has finished. Since this casting opera-tion is conducted in accordance with the above-ment.ioned numer,ically limited condi-tions and program, the melt 15 fills the cavities 3 relatively calmly and continuously at a low rat'e without permi-tt.ing gas to enter the melt. ' When the ratio oE the volume (,cm ) of products at~the gates.4 to.the cross-sec-tional area (cm2) of the gates is less than 20, the melt flows into the cavities by its own weight too quickly, or the gravity-feeding time becomes short, so that the optimum range is narro~. When this ratio exceeds 40, the injection of the melt into the cavities by the for~e of gravity progresses too slowly, and the percentage of melt put in the cavities by the force of gravity becomes lo~, so that the melt which has passed through the gates is disordered, causing gas to mix the melt and cold shut to occur.
When a point representing the relation between the speed of plunger tip 9 and the length of the period of time between the commencement of a downward movement of the plunger tip 9 and the opening of the gates by the counter-tip 7 is the above the maximum speed curve shown in Fig. 5, the pressure filling operation starts too early as mentioned before. When this point is below the minimum speed curve of the melt by the ; force of gravity stop before the pressure filling operation start. Either of these cases yields defective cast products.
r _ g _ ms/ ~?~
Howevex~ because of the following problems, these casting methods do not yielcl high quality cast products and the productivity cannot be improved . In gravity casting and low-pressure casting, the melt is not forcibly pressurized, so that so-called shrinkage holes occur in it in the solidi~ying step. Consequently, ~- 2 --~' ms/~ ~
sound products cannot be obtained. Mor~over, the so].idif~iny rate in these cast:ing methods is low, decreasing the produc-tivity.
Inpressure die casting, the sleeve-charging ~ercen-tage is 50-70, and, moreover, the melt is introduced into cavities under pressure at a high rate. Accordingly, the gas in certain portions of the passage for the melt, such as gates, and in the cavities is liable to mix with the melt, decreasing the reliability of the quality of the products.
With a view to eliminating the above-mentioned incon-veniences, a vertical type die casting method has been developed, which has a sleeve-charging percentage of 100, and in which the melt is pressurized without mixing with gas in the gates and cavities. Howèver, this casting method also has some pro~lems which have not yet been completely solved with respect to sof-t materials for obtaininc3 high-quality products, namely the casting conditions and a casting program in relation to the casting mechanism. Thus, the advantages of this casting method cannot be utilized effect-ively.
SUMMARY OF TH~ INVENTION
An object of the present invention is to provide an excellent vertical type pressure casting me-thod, which has been developed in view of the problems with the above-mentioned vertical type casting method, which was developed 1~;
'7 to supersede the existing casting me-thocl usincJ metal molds, and which has various advantages bu-t does not give full play to its functions. The casting condi-tions include -the speed of the plunger and the -temperatures of the molds and melt, and the desicJn conditions include the percentage of melt to be introduced into cavities by -the force of gravity, and the cross-sectional area of gates in the Method according to the presen-t invention being set to levels in optimum ranges with respec-t -to one another, whereby highly reliable high-quality products can be cast.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings show an embodiment of the present invention, wherein:
Fig. 1 is a schematic diagrarn o.f a vertical type pres-sure casting appara-tus;
Figs. 2, 3 and 4 illustrate the process for pouring the melt through gates into cavities;
Fig. 5 is a diagram illustrating the rela-tion between the speed of downward movement of the plunger tip and the length of a period of time from the commencement of downward movement of the plunge~ unit and the opening of the gates by a counter-tip; and Fig. 6 is a graph showing percentages of inferior products in the embodiment and a conventional method.
'7 DETAILED DESC~IPri`ION OF T}lr' P~-`FERRED ~MBODIMENT
An embodiment of the present invention will now be described with reference to the accompanying drawings.
Fig. 1 shows h vertical type pressure casting apparatus used in the method according to the present invention. A
lower mold 1 and an upper mold 2 are clamped together to form cavities 3, 3. Gates 4 for the cavities 3, 3 face the interior of a sleeve 5. A counter-tip 7 connected to a hydraulic cylinder 6, and a plunger tip 9 connected to a hydraulic cylinder 8 are provided opposing each other in lower and upper positions, respectively, in the sleeve 5 such that the counter~tip 7 and plunger tip 9 can be moved up and down therein. A solenoid in a changer-over valve 10 connected to hydraulic cylinder 6 is controlled by a limit switch 12 with respect to a dog provided on the rod of plunger tip 9.
The melt 15 is poured from a melt inlet port 13 into the sleeve 5 by a ladle 14.
The above apparatus is designed so that the ratio of the volume (cm ) of the prod~lct to-the cross~ n~l area (cm2) of the gates 4, which is one of the construction parameters of the apparatus, is 20-40.
The operational conditions and program for the present invention to be practiced by using the apparatus of this construction are set to attain the following: The plunger tip 9 is moved downward to lower the counter-tip 7 through ~13~ 1'J~J
-the dog 11 and limit switch 12. The rela-tion between the speed V m/sec at which the plunger ti.p 9 moves downward and the length of -ti.rme T sec from -the commencement of the downward movemen-t of -the plunger -tip 9 to the openi,ng of the gates ~ by the counter tip 7, is set to an optimal value with reference -to the information shown in Fig. 5. Namely, the speed, at which the plunger tip moves down is set to a level between the upper limit level in an upper limit speed curve Rl, above which the plunger tip 9 moves down too East and reaches the upper surface of the melt 15 in the sleeve 5 to start the pressure-filling operation before the gates 4 have been opened by the counter tip 7, and a lower limit level in a lower limit speed curve R2, above which the plunger tip ~ reaches the upper surface of the melt 15 in the sleeve 5 after the gates ~ have been fully openecl by the counter tip 7 allowing the melt 15 to flow into the cavities by the force o~ gravity until the flow of melt has stopped, whereby -the melt 15 can be fed to the cavities calmly and continuously at a low rate.
According to the experimental resul.ts, the percenta~e distribution of acceptable cast products with respect to the whole number of cast products obtained under different conditions is as shown in the data in Fig. 5.
A: not less than 90% B: 50-90%
C: 20-50% D: not more than 20%
This relation between the speed of the plunger tip and the leng-th o~ a period of time between the cor~encement of the downward movement of the plunger and the opening of the gates can also be set differently by varying not only the cross-sectional area of the gates but also the temperatures of the molds and melt.
After the cross-sectional area of the gates and the temperatures of the molds and melt have been determined, the percentage of the melt to be fed into the cavities by the force of gravity before the plunger tip 9 reaches the upper surface of the melt 15 in the sleeve 5 is set to 20-70, and the speed of the melt through the gates during the feeding of the melt to the cavities by the force of gravi-ty to not less than 0.1 m/sec with the speed of the melt through the gates when pressure~filling the cavities using the plunger tip 9 set to 0.4-0.8 m/sec.
The molds are clamped as shown in Fig. 1 with the castiny apparatus set in accordance with the above-mentioned casting conditions and prog-~am, and the hydraulic cylinder 6 is actuated to close the gates 4 with the counter--tip 4.
The hydraulic cylinder 8 is then actuated to set the plunger tip 9 to an initial attitude position~
A predetermined amount of melt 15 is then poured from a melt inlet port 13 into the sleeve 5, and a button for a control unit (not shown) is pressed to actuate the hydraulic cylinder 8 to start the casting operation in accordance with the cas-ting conclitions and program referred to above.
First, when the plunger tlp 9 starts being moved downward a-t a predetermined speed with the dog 11 coming into contact with the limi-t switch 12, the counter-tip 7 is moved downward at a predetermined time by operation of the change-over valve 10 before the plunger tip 9 has reached the upper surface of the melt 15 in the sleeve 5 as shown in Fig. 2, in accordance with the relation between the set speed and -time shown in Fig. 5, to open the gates 4. The melt 15 then starts flowing from the gates 4 into the cavities 3 by the force of gravity.
After a predetermined period of time has passed, the plunger -tip 9 reaches the upper surface of -the melt 15 (which is, of course, flowing in-to the cavi.ties by the force of gravity) in the sleeve 5. At this time, the percentage of the melt placed in the cavities is 20-70 as mentioned above.
The melt-feedlng by the force of gravity is then changed to pressure-filling as shown in Fig. 4. The speed of the melt through the gates during pressure-filling by the plunyer tip 9 is set to 0.4-0.8 m/sec as mentioned above.
Thus, in the casting operation as a whole according to the present invention, the melt 15 in the sleeve 5 is fed into the cavities by its own weight, i.e. by the force of gravi-ty, in the initial s-tage, and under pressure by ''7 the plunger tip 9 be:Eore -the gravity feeding operation has finished. Since this casting opera-tion is conducted in accordance with the above-ment.ioned numer,ically limited condi-tions and program, the melt 15 fills the cavities 3 relatively calmly and continuously at a low rat'e without permi-tt.ing gas to enter the melt. ' When the ratio oE the volume (,cm ) of products at~the gates.4 to.the cross-sec-tional area (cm2) of the gates is less than 20, the melt flows into the cavities by its own weight too quickly, or the gravity-feeding time becomes short, so that the optimum range is narro~. When this ratio exceeds 40, the injection of the melt into the cavities by the for~e of gravity progresses too slowly, and the percentage of melt put in the cavities by the force of gravity becomes lo~, so that the melt which has passed through the gates is disordered, causing gas to mix the melt and cold shut to occur.
When a point representing the relation between the speed of plunger tip 9 and the length of the period of time between the commencement of a downward movement of the plunger tip 9 and the opening of the gates by the counter-tip 7 is the above the maximum speed curve shown in Fig. 5, the pressure filling operation starts too early as mentioned before. When this point is below the minimum speed curve of the melt by the ; force of gravity stop before the pressure filling operation start. Either of these cases yields defective cast products.
r _ g _ ms/ ~?~
3~'7 ~ hen a gravity-feeding operation is shifted to a pressure-filling operation, the melt should be placed in the cavities relative smcothl~, quietly, at a low rate, and in a con-tinuous manner. When the percentage of the melt which flows into the cavities by the force of gravity, a gravity-feeding percentage, is lower than 20, the pressure-filling operation starts too early. When this percentage exceeds 70, the gravity-feeding operation is carried out excessively.
Therefore, in either of these cases, the gravity-feeding operation cannot be shifted to the pressure-filling opera-tion immediately and smoothly, so that gas mix the melt and cold shut occurs.
When this casting apparatus is designed so that, a pressure-filling operation is not conducted during a gravity-feeding operation only,i.e. the melt flows into the cavities by only the force of gravity, a percentage o~
melt to be placed in the cavities by the force of gravity is set to at least 30 and then pressùre filling is conducted supplementarily. When the percentage of melt to he placed in the cavities by the force of gravity is set in this manner, gas can be prevented from entering the products.
Consequently, when the casting apparatus is designed so that the percentage of melt to flow into -the cavities by the force of gravity only is below 30, the pressure-filling operation is conducted e~cessively. In this case, no optimum range of casting conditions is available.
-- 1,0 --r ~
L3;~'7 ~ en Lhe spee~ of ~he melt through the gates d~lring the pressure-filling operation is below 0.4 m/sec, the~
melt does not flow in a satisfactory manner, and when this speed exceeds 0.8 m/sec, a gas enters the melt.
A comparison between the results in different ~odes M of castinq methods, namely a conventional methold Ll of die casting and a method L2 used in an experiment conducted in accordance wi~h the above embodiment of the present invention, the percentage E of inferior products, especially, a percentage F of inferior products due to the leakage of pressure and a percentage G of inferior products which fail to pass an X-ray inspection, shows as is clear from Pig. 6 that the percentages F, G in the method Ll are far higher than those in the method L2, the casting method according to the present invention permits obtaining extremely good products.
As described above, by the present invention faultless products which have basically high quality can be man~factured, and it has excellent effect.
I~oreover, the casting conditions and program can be set or determined easily, and the time and cost for conducting exDeriments and modi~ying the metal molds can be reduced to a re~iarkable extent.
;~ Since the gates are formed in such a manner that a ratio of volume (cm3) of products to a cross-sectional area of ~; the gates (cm2) is 20-40, gas does not mix in the melt and y~
': :
no cold shut occurs. Therefore, fau]tless ~rod~cts can be obtained.
The speed at which the plunger tip is moved down until the counter-tip is displaced to open the gates is set to an optimum level which makes the plunger tip to reach the uDper surface of the melt in the sleeve between the time the melt starts flowing into the cavities by the force of gravity, and the time, at which the gravity-feeding of the melt is finished~ Accordingly, a very high percentage of satisfactory products can be obtained.
When the casting program, in which a percentage of the melt to be placed in the cavities by the force of gravity only is set to not less than 30%, is prepared experimentally such ~at the percentage of the melt to flow into the cavities by the f~rce of gravity before the plunger tip reaches the upper surface of the melt in the sleeve is 20-70, an operation for feeding the melt into the cavities by the force of gravity can be shifted relative ~ot'nly, ~ etly, at a low rate and in a continuous manner to an operation for pressure-filling the cavities therewith. This allows fault-less products to be obtained.
Since the speed of the melt through the gates during the pressure-filling operation is set to 0.4-0.8 m/sec, gas does not enter the cavities, and the melt can be put in the cavities in a desired manner as mentioned above.
' . ~
:
Therefore, in either of these cases, the gravity-feeding operation cannot be shifted to the pressure-filling opera-tion immediately and smoothly, so that gas mix the melt and cold shut occurs.
When this casting apparatus is designed so that, a pressure-filling operation is not conducted during a gravity-feeding operation only,i.e. the melt flows into the cavities by only the force of gravity, a percentage o~
melt to be placed in the cavities by the force of gravity is set to at least 30 and then pressùre filling is conducted supplementarily. When the percentage of melt to he placed in the cavities by the force of gravity is set in this manner, gas can be prevented from entering the products.
Consequently, when the casting apparatus is designed so that the percentage of melt to flow into -the cavities by the force of gravity only is below 30, the pressure-filling operation is conducted e~cessively. In this case, no optimum range of casting conditions is available.
-- 1,0 --r ~
L3;~'7 ~ en Lhe spee~ of ~he melt through the gates d~lring the pressure-filling operation is below 0.4 m/sec, the~
melt does not flow in a satisfactory manner, and when this speed exceeds 0.8 m/sec, a gas enters the melt.
A comparison between the results in different ~odes M of castinq methods, namely a conventional methold Ll of die casting and a method L2 used in an experiment conducted in accordance wi~h the above embodiment of the present invention, the percentage E of inferior products, especially, a percentage F of inferior products due to the leakage of pressure and a percentage G of inferior products which fail to pass an X-ray inspection, shows as is clear from Pig. 6 that the percentages F, G in the method Ll are far higher than those in the method L2, the casting method according to the present invention permits obtaining extremely good products.
As described above, by the present invention faultless products which have basically high quality can be man~factured, and it has excellent effect.
I~oreover, the casting conditions and program can be set or determined easily, and the time and cost for conducting exDeriments and modi~ying the metal molds can be reduced to a re~iarkable extent.
;~ Since the gates are formed in such a manner that a ratio of volume (cm3) of products to a cross-sectional area of ~; the gates (cm2) is 20-40, gas does not mix in the melt and y~
': :
no cold shut occurs. Therefore, fau]tless ~rod~cts can be obtained.
The speed at which the plunger tip is moved down until the counter-tip is displaced to open the gates is set to an optimum level which makes the plunger tip to reach the uDper surface of the melt in the sleeve between the time the melt starts flowing into the cavities by the force of gravity, and the time, at which the gravity-feeding of the melt is finished~ Accordingly, a very high percentage of satisfactory products can be obtained.
When the casting program, in which a percentage of the melt to be placed in the cavities by the force of gravity only is set to not less than 30%, is prepared experimentally such ~at the percentage of the melt to flow into the cavities by the f~rce of gravity before the plunger tip reaches the upper surface of the melt in the sleeve is 20-70, an operation for feeding the melt into the cavities by the force of gravity can be shifted relative ~ot'nly, ~ etly, at a low rate and in a continuous manner to an operation for pressure-filling the cavities therewith. This allows fault-less products to be obtained.
Since the speed of the melt through the gates during the pressure-filling operation is set to 0.4-0.8 m/sec, gas does not enter the cavities, and the melt can be put in the cavities in a desired manner as mentioned above.
' . ~
:
Claims (4)
1. A vertical type pressure casting method having the steps of closing gates to cavities with a counter-tip after molds have been clamped, pouring melt into a sleeve with a plunger tip therein in a lifted state, displacing said counter-tip to open said gates and allow the melt to flow into said cavities via said gates by the force of gravity, and thereafter pressurizing the melt in said sleeve by moving said plunger tip downward to fill said cavities with said melt, characterized in that a casting program is used, by which program said gates are opened by said counter-tip after said plunger tip has started moving downward, and the speed of said plunger tip during the period of time from the commencement of its downward movement to the opening of said gates is set to a speed between the speed at which said plunger tip reaches the melt in said sleeve when or before said gates are opened by said counter-tip, and the speed at which said plunger tip reaches the melt at the time the melt stops flowing into said cavities by the force of gravity alone.
2. A vertical type pressure casting method according to Claim 1, wherein said gates are formed in such a manner that a ratio of the volume of products to the cross-sectional area of said gates is 20-40 (volume of products (cm3)/
cross-sectional area (cm2) = 20-40), if the plunger tip does not move, the percentage of melt to flow into said cavities by the force of gravity alone is set to not less than 30, the percentage of the melt to be fed into said cavities by the force of gravity before said plunger tip reaches the melt in said sleeve is set to 20-70, the speed of the melt through said gates during the pressure-filling of said cavities by said plunger tip is set to 0.4-0.8 m/sec.
cross-sectional area (cm2) = 20-40), if the plunger tip does not move, the percentage of melt to flow into said cavities by the force of gravity alone is set to not less than 30, the percentage of the melt to be fed into said cavities by the force of gravity before said plunger tip reaches the melt in said sleeve is set to 20-70, the speed of the melt through said gates during the pressure-filling of said cavities by said plunger tip is set to 0.4-0.8 m/sec.
3. A vertical type pressure casting method according to Claim 1 or 2, wherein the speed of the melt through said gates during the feeding of the melt into said cavities by the force of gravity is set to not less than 0.1 m/sec.
4. A vertical type pressure casting method having the steps of closing gates for cavities with a counter-tip after molds have been clamped, pouring melt into a sleeve with a plunger tip therein in a lifted state, displacing said counter-tip to open said gates and allow the melt to flow into said cavities through said gates by the force of gravity, and thereafter pressurizing the melt in said sleeve by moving said plunger tip downward to fill said cavities with said melt, characterized in that a casting program is used, by which program said gates are opened by said counter-tip after said plunger tip has started being moved downward, said plunger tip has a speed during the period of time starting with the commencement of the downward movement of said plunger tip and ending with the opening of said gates set to a speed between the speed at which said plunger tip reaches the melt in said sleeve by the time said gates have been opened by said counter-tip, and the speed at which said plunger tip reaches the melt the moment the melt stops flowing into said cavities by the force of gravity alone; forming said gates in such a manner that the ratio of the volume of products to the cross-sectional area of said gates is 20-40; and permiting not less than 30% of the melt to flow into said cavities by the force of gravity alone, the percentage of the melt to be fed into said cavities by the force of gravity before said plunger tip reaches the melt in said sleeve being set to 20-70, and the speed of the melt through said gates during the pressure-filling of said cavities with the plunger tip being set to 0.4-0.8 m/sec.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000403386A CA1191327A (en) | 1982-05-20 | 1982-05-20 | Vertical type pressure casting method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000403386A CA1191327A (en) | 1982-05-20 | 1982-05-20 | Vertical type pressure casting method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1191327A true CA1191327A (en) | 1985-08-06 |
Family
ID=4122821
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000403386A Expired CA1191327A (en) | 1982-05-20 | 1982-05-20 | Vertical type pressure casting method |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1191327A (en) |
-
1982
- 1982-05-20 CA CA000403386A patent/CA1191327A/en not_active Expired
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