US3620293A

US3620293A - Press molding machine with adjustable feed device

Info

Publication number: US3620293A
Application number: US814040A
Authority: US
Inventors: Ernst Otto Kruse
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-04-07
Filing date: 1969-04-07
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16

Abstract

A desired degree of compaction of molding sand within a mold flask part is achieved by ramming a pressure plate to a fixed end position with respect to the mold flask part while bleeding liquid from a yielding pressure head to allow attainment of the end position without exceeding the desired degree of compaction. The amount of molding sand subjected to compaction in the next cycle is controlled by the amount of liquid so displaced.

Description

United States Patent 72] Inventor Ernst Otto Kruse Pattenser Str. 48, Reden/Hannover, Germany [2 1] App]. No. 814,040

[22] Filed Apr. 7, 1969 [45] Patented Nov. 16, 1971 [54] PRESS MOLDING MACHINE WITH ADJUSTABLE FEED DEVICE 5 Claims, 6 Drawing Figs.

[52] U.S.CI 164/154, 164/170 [51] int. Cl. ..B22c 19/04, B22c 15/08 [50] Field of Search 164/170,

[56] Reierences Cited UNITED STATES PATENTS 2,956,317 10/1960 Peasley 2,962,775 12/1960 Rekafl..." 3,172,173 3/1965 Ellms Primary Examiner-Robert D. Baldwin Assistant Examiner-John S. Brown Attorney-imirie and Smiley ABSTRACT: A desired degree of compaction of molding sand within a mold flask part is achieved by ramming a pressure plate to a fixed end position with respect to the mold flask part while bleeding liquid from a yielding pressure head to allow attainment of the end position without exceeding the desired degree of compaction. The amount of molding sand subjected to compaction in the next cycle is controlled by the amount of 1 liquid so displaced.

PATENTEUNUV 16 |97l 3,620,293

SHEET 1 OF 4 IN VEN TOR.

ERNST OTTO KRUSE PATENTEDNUV .18 IHYI 3 62D 2 93 SHEET 2 BF 4 INVENTOR.

ERNST OTTO KRUSE ATTORNEYS PATENTEUunv 16 I971 SHEET 3 BF 4 FIG.5

I N V EN TOR.

ERNST OTTO KRUSE W SQZJ ATTORNEYS PRESS MOLDING MACHINE WITI-I ADJUSTABLE FEED DEVICE BACKGROUND OF THE INVENTION It is well known in the mold-making machine art that if the pattern plate is moved or rammed toward a pressure head so that the sand is compacted within the mold flask part against the fixed pressure head, the sand compaction characteristics are superior to those obtained if the pattern plate is held stationary and the pressure head rammed toward it. In brief, the fonner produces a compaction of the sand which is greatest at the pattern print and decreases in the direction toward the pressure head, thus obtaining a more accurate and sharp pattern print and also favorably influencing the gas permeability characteristics of the thus compacted molding sand with respect to the mold cavity.

However, adoption of this technique gives rise to a very serious problem which stems from the fact that two essential conditions, namely the accurate positioning of the pattern plate with respect to the mold flask part at the end of the pattern plate stroke and the degree of sand compaction desired, are difficult to obtain simultaneously. If the stroke of the pattern plate is controlled always to be correct with respect to the mold flask part, the compaction is apt to be outside acceptable limits; whereas if the compaction is controlled to be within acceptable limits, the position of the pattern plate at the end of its stroke is apt to be incorrect with respect to the mold flask part, thus disastrously locating the parting line of the mold sand with respect to the mold flask part. This problem is further aggravated by virtue of the fact that the moisture of molding sand often varies considerably so that its compaction characteristics vary as well.

BRIEF SUMMARY OF THE INVENTION This invention relates to an improved molding machine which allows the use of a movable pattern plate for effecting the compaction of the molding sand within the mold flask part while still allowing the pattern plate to be accurately positioned at the end of its stroke with respect to the mold flask part and while also maintaining the sand compaction within the desired limits. In general, this is accomplished by compacting the sand between the movable pattern plate and a fixed pressure head of yieldable character. The yieldable pressure head includes a chamber filled with fluid which is displaced upon attainment of a predetermined maximum pressure therein so as to allow the pattern plate to reach the end of its stroke without effecting over compaction of the molding sand within the mold flask part.

The present invention also contemplates the above general arrangement with the utilization of means for measuring the quantity of fluid displaced during the compaction step to control the quantity of molding sand subjected to compaction in the next successive cycle of operations. Preferably, this control is effected by adjusting the next initial position of the pattern plate to be nearer to or farther from its end stroke posi tion. In this way, the quantity of molding sand fed to the machine during each cycle may be adjusted so as to be less wasteful of molding sand and, perhaps more importantly, variations in moisture content of the sand may be accommodated for automatically.

BRIEF DESCRIPTION OF THE DRAWING FIGURES FIG. 1 illustrates in section an embodiment of a molding machine according to this invention, the components thereof being disposed in fill position;

FIG. 2 is a view similar to FIG. 1 but showing the pressure head in position for allowing the sand to be compacted thereagainst;

FIG. 3 is a view similar to FIGS. 1 and 2, but showing the disposition of parts at the end of the compression or compaction stroke;

FIG. 4 is a view similar to FIG. 1 but showing the position of the components subsequent to compaction and preparatory to striking off excess sand;

FIG. 5 shows the manner in which return movement of the pressure head effects removal of the excess sand, and

FIG. 6 is a view similar to FIG. I but showing a further embodiment of the molding machine.

DETAILED DESCRIPTION OF THE INVENTION With reference now more particularly to FIG. 1, the princi ples of the present invention will be evident therefrom. As shown, the mold-making machine includes a suitable framework 10 which is provided with an overhead rail 12 from which is suspended the yieldable pressure head mechanism indicated generally by the reference character 14, same being provided with suitable rollers 16 engaging a flange 18 at each side of the rail. Suitable mechanism is provided, not shown, for moving the pressure head assembly 14 between the positions shown in FIGS. 1 and 2. The pressure head assembly 14 includes the main frame portion 20 provided with a recess 22 which is closed off on its lower side by a flexible diaphragm 24, the chamber afforded between the vecess and the diaphragm being filled with liquid as indicated by the reference character 26. The diaphragm or membrane 24 may be secured in place by a locking frame element 28 which peripherally engages the membrane or diaphragm and holds same in fixed relation with the frame 20. The chamber containing the liquid 26 is provided with a bleed passage 30 which is connected to a pressure relief valve 32, the purpose of which will be presently apparent.

The frame 20 of the pressure head assembly 14 carries suitable lateral support means 34 upon which a striker plate 36 is pivotally attached as by the pivot pin 38, substantially as is shown. Suitable mechanism, not shown, is provided for disposing the striker plate 36 in the alternate positions shown respectively in FIGS. 1 and 4, the purpose of which will be presently apparent.

Suitably mounted on the frame 10 of the mold machine are spaced courses of

rollers

40 and 42 or other suitable support means which are adapted to support the mold flask member 44 allowing it to be transported into registered disposition with respect to the pattern well or filling frame member 46. The filling frame 46 is supported for vertical movement by means of the piston rods 48 which are supported in suitable guide 50 carried by the frame part 52 and the enlarged lower ends 54 of these piston rods are received in cylinders 56 which have hydraulic pressure connections 58 allowing the filling frame assembly to be raised and lowered as will be evident hereinafter.

The frame also includes a pattern plate cylinder 60 presenting a fluid chamber 62 within which the piston 64 of the pattern plate assembly is disposed, there being hydraulic

fluid pressure connections

66 and 68 at opposite ends of this cylinder which extend to the control valve mechanism 70 supplied by a pump 72 from a suitable hydraulic fluid reservoir indicated by the reference character 74. The column or piston rod 76 of the pattern plate assembly presents an upper head portion 78 upon which a pattern plate member 80 is removably fixed substantially as is shown, the pattern plate being of conventional form and having a pattern portion 82 as will be recognized by those skilled in the art.

The device generally described above is adapted for cyclic operation automatically to produce the requisite mass of compacted and shaped sand within the mold flask parts. As will be recognized by those skilled in the art, the cope and drag portions so produced are operatively united and the molten metal poured into the mold cavity afforded thereby. Thus, with the various parts initially disposed, at the beginning of a cycle. in the position shown in FIG. 5, the mold flask part 44, either the cope or drag, is brought into position along the

rollers

40 and 42 in registry above the filling frame 46. At this time, the pistons 54 of the filling frame 46 are in lowered position within their respective cylinders 56 and as soon as the cope or drag 44 is registered as described, the cylinders 56 are pressurized through the conduits 58 to raise the filling frame 46 to the position shown in FIG. 1. During this time, the pattern plate assembly remains in fixed position. Thus, with the parts now positioned as shown in FIG. 1, the filling frame 46, the mold flask part 44 and the pattern plate 80 cooperate to provide a well within which sand may be received and the volume of this well below the upper face 83 of the mold flask part 44 is of some value which may be altered by relative vertical positioning of the pattern plate 80. When the parts are in the position described, a conveyor mechanism 84 is operated to deliver a quantity of sand 86 which is sufficient to overfill the well so that the top of the pile of sand 86 extends above the aforementioned upper face 83 of the mold flask part 44. The pressure head assembly 14 is then actuated from the position shown in FIG. 1 to the position as shown in FIG. 2, during which time the striker plate 36 will strike off the sand 86 flush with the upper surface 83 of the mold flask part 44 whereby the sand remaining in the well is equal to the volume of the well defined by the

members

44, 46 and 80 as aforesaid. With the parts now in the position shown in FIG. 2, the pattern plate assembly is moved upwardly to the top end of its stroke, as shown in FIG. 3, wherein the parting line 88 of the sand thus compacted within the mold flask part 44 and against the pressure head assembly 14 is flush with the lower face 90 of the mold flask part 44. It is an important aspect of this invention that the end stroke position of the pattern plate assembly always attains this relationship, thus assuring that the parting line 88 and the print formed by the pattern 82 are properly disposed with respect to the mold flask part 44 so that when the respective cope and drag parts of the mold flask are later brought together, the mold cavity is properly formed as will be evident to those skilled in the art.

During the compaction process as shown in FIG. 2, the volume of the chamber containing the liquid 26 is reduced due to the fact that deformation of the membrane 24 will expel or bleed some of the liquid 26 through the conduit 30 as soon as the pressure of this liquid exceeds the release pressure to which the valve assembly 32 is set. For this purpose, it will be understood that the valve 32 may be set to bleed off liquid at a desired pressure and it will be understood also that the pres sure so selected obtains the degree of compaction desired for the sand 86 within the mold flask part 44. The liquid so bled off is conducted through a conduit 90 to a cylinder 92 within which a piston 94 is disposed. Dependent upon the volume of liquid bled off into the cylinder 92, the piston 94 will rise to imparta corresponding stroke to the gear rack or equivalent member 96 with which the spur gear 98 of an electrical signal generator 100 is engaged. Thus, the signal generator 100 produces a signal whose amplitude is proportional to the volume of liquid expelled from the yieldable pressure head chamber and thereby provides an indication of the amount of excess sand initially contained within the well after the sand was struck off as shown in FIG. 2. This signal is supplied, as indicated by the reference character 102 in FIG. 1, to a com parison and storage circuit 104. A further signal produced by the signal generator 106 is fed to the circuit 104, which signal is derived from the stroke of the pattern plate assembly by virtue of actuation of the signal generator 106 through the spur gear 108 in mesh with the rack 110, which is fixed to and movable with the pattern plate assembly, substantially as is shown. The circuit 104 forms per se no part of the present invention but is effective to provide and store a signal which, at a later time in the cycle, controls the position to which the pattern plate is returned so as to reduce or increase the volume of the well below the surface 83. This is effected by applying the output signal at 114 from the device 104 to a solenoid or other actuator 116 connected to the valve 70 to actuate same for a period of time dependent upon the amplitude of the signal at 114, thereby to connect the conduit 66 to the pressure outlet connection 118 of the pump 72 and the conduit 68 to the hydraulic fluid return line 120 for that predetermined period of time as computed by the mechanism 104 which will establish the proper lowered position ofthe pattern plate assembly. As soon as this position is reached, the valve is brought to the intermediate position-shown in FIG. 1 wherein both

conduits

66 and 68 are blocked. Of course, for raising the pattern plate assembly as shown in FIG. 3 the pressure side 118 of the pump 72 is connected directly to the conduit 68 and the return line is connected to the conduit 66, it being appreciated that the end position of the stroke of the pattern plate assembly is fixed during each cycle so that the parting line 88 described in conjunction with FIG. 3 is always coplanar or level with the lower face 90 of the mold flask part 44.

It will be appreciated that some degree of excess sand in the well is desired so that the reaction print" 87 produced by the yieldable pressure head during the compaction stroke (see FIG. 4) does not extend below the face 83. For this reason, the equilibrium condition, i.e. the amplitude of the signal at 114 produced by the amount by which signal 102 is less than signal 112 and which will return the pattern plate to the same position for the next cycle, is chosen such that this excess of sand will be accommodated by the well. It will be appreciated also that it may be desirable to reduce or increase the volume of sand delivered by the mechanism 84 during each cycle correspondingly as the well volume is decreased or increased, thereby to minimize the amount of sand struck off after the initial filling operation. In any event, the prime consideration is to allow the pattern plate to attain its final or'upper position at exactly the same point each time while simultaneously attaining the desired degree of compaction of the sand. The amount of sand trapped between the pattern plate and pressure head is adjusted to provide a minimum quantity of excess sand (FIG. 4) which still allows a smooth sand surface after strike-off (FIG. 5).

Thus, after compaction as shown in FIG. 3, the pattern plate assembly and the filling frame 46 are lowered, as shown in FIG. 4, so that the mold flask part 44 is returned to the

rollers

40, 42 and the striker plate 36 is actuated to the position shown in FIG. 4 and the pressure head assembly 14 is returned to its initial position as shown in FIG. 5 whereby the excess sand is struck off the top of the mold flask part to lie flush with the upper face 83 thereof previously described. The filling frame 46 continues to its fixed lowered position and the pattern plate assembly is lowered to that position as dictated by the

mechanisms

104 and 116, as described hereinabove. At the same time, a valve 124 is actuated to connect the conduit 126 to a source of fluid such as air under pressure, as indicated by the reference character 128, so as to return the piston 94 to its lowered position within the cylinder 92 thus returning the bleedofi liquid to the chamber of the pressure head assembly. The valve 124 is so positioned during the compaction stroke that the conduit 126 is vented, as will be evident.

A modified form of the invention is shown in FIG. 6 wherein components constructed identically with the assembly as described hereinabove are provided with like reference characters. In the embodiment shown in FIG. 6, the pattern plate assembly is provided with a reference member 130 which is associated with a detecting device 132 mounted for vertical adjustment on the screw 134 under the control of the drive motor 136 therefor. Similarly, the piston 94 is provided with a rod member 138 presenting an indicator 140 which is associated with a detecting means 142. The two detecting

means

132 and 144 produce signals at their

respective connections

144 and 146 when the respective indicators are opposite these detectors and these signals are applied to the mechanism 148 which control the actuator 116 as previously described, and, as well, is connected as indicated by the reference character 150 to the drive motor 136 to operate it in a manner presently to be described. The operation of the system of FIG. 6 is such that the dector 142, acting as a limit switch, serves to provide a signal which is of nominal value signal and this switch may be positioned manually with respect to the cylinder 92 to determine the normal value of the sandfill. The limit switch 132 serves as an actual value signal generator. In operation, if insufficient liquid is displaced or bled from the pressure head liquid chamber, no signal will be produced by the limit switch or detector 142 and, correspondingly, a signal is generated by the mechanism 148 to lower the detector 132 by actuation of the motor 136. The detector is moved finite but fixed amount each time a signal is generated to move it. Thus, when the pattern plate assembly is lowered for the next cycle, it will stop at a lower position than in the preceding cycle by the amount by which the detector 132 is stepped downwardly as described, it being appreciated that the limit switch 132 serves to terminate actuation by the mechanism 116 of the valve 70 for the lowering movement of the pattern plate assembly. If, on the next stroke, the detector 142 still does not detect the presence of the indicator 140, the limit switch 132 is further lowered and this stepwise lowering will continue until the condition in which the detector 142 produces a signal is reached. Conversely, if the amount of liquid displaced from the pressure head assembly 14 is too great, the limit switch 144 will produce first a signal at 146 and then the signal will cease since the indicator 140 will pass the detector 144. This will cause the limit switch 132 to be actuated upwardly in stepwise fashion by the motor 136 during each successive cycle until, as in the preceding discussion, the system reaches a condition in which the indicator is opposite the detector 144 and produces an output signal therefrom at the end of the compaction stroke.

The entities and connections for effecting cyclic operation and the details of the

circuits

104 and 148 are not specifically described. Their details, per se, form no part of the present invention and since those skilled in the art may easily construct devices to perform the required logic, as described above, further showing and description is believed to be superfluous.

I claim:

1. A mold-making machine comprising, in combination,

an open filling frame,

a mold flask member disposed in registry with said filling frame,

and a pattern member positioned within said filling frame,

said filling frame, said mold flask member and said pattern member defining a well for receiving molding sand, means for delivering molding sand to said well,

yieldable means for closing off the top of said mold flask member to confine the sand within said well between said yieldable means and said pattern member,

means for moving said pattern member toward said yieldable means to a predetermined position with respect to said molding flask member, thereby to compact molding sand within said molding flask member against said yieldable means while establishing a desired parting line for the molding sand with respect to said mold flask member,

said yieldable means including a chamber filled with fluid which is pressurized in response to compaction of the sand, and means for permitting displacement of said fluid upon attainment of a predetermined pressure therein, thereby to limit the degree of compaction of the molding sand within said molding flask member,

means for measuring the quantity of fluid displaced during the stroke of said pattern member,

and means for controlling the amount of sand received by said well during the next successive cycle in response to said quantity of fluid displaced.

2. The mold-making machine according to claim 1 wherein said means for controlling varies the stroke of said pattern member.

3. The mold-making machine according to claim 2 including means for measuring the stroke of said pattern member, said means for controlling being effective to compare the measurement of said stroke with the quantity of fluid displaced.

4. In a mold-making machine of the type including a filling frame adapted to support a mold flask member thereon, a pattern plate moveable within said filling frame between a lowered position and an upwardly extended position for compacting sand within the mold flask member, and means for periodically feeding sand onto said pattern plate, the improvement compfising: D

a yielda le pressure head moveable into position over the mold flask member and against which sand is compacted by said pattern plate, said yieldable pressure head including a liquid-filled chamber which is pressurized in response to compaction of the sand, and means for bleeding liquid from said chamber upon attainment of a predetermined pressure therein,

means for varying the lowered position of said pattern plate in response to the volume of liquid bled from said chamber,

said last-mentioned means including a cylinder for receiving liquid bled from said chamber, and a piston in which said cylinder moveable in response to reception of liquid within said cylinder,

a first signal generator actuated by said piston and having an output signal proportioned to movement of such piston,

a second signal generator actuated by said pattern plate and having an output signal proportional to the stroke of said pattern plate,

and means for comparing said output signals to return said pattern plate to a lowered position determined by the difference therebetween.

5. In a mold-making machine of the type including a filling frame adapted to support a mold flask member thereon, a pattern plate moveable within said filling frame between a lowered position and an upwardly extended position for compacting sand within the mold flask member, and means for periodically feeding sand onto said pattern plate, the improvement comprising:

a yieldable pressure head moveable into position over the mold flask member and against which sand is compacted by said pattern plate, said yieldable pressure head including a liquid-filled chamber which is pressurized in response to compaction of the sand, and means for bleeding liquid from said chamber upon attainment of a predetermined pressure therein,

said lastwnentioned means including a cylinder for receiving liquid bled from said chamber, and a piston in said cylinder moveable in response to reception of liquid within said cylinder,

a first detector for producing an output signal when said piston is moved to a predetermined position,

a second detector for terminating lowering motion of said pattern plate,

and means for moving said second detector in stepwise fashion to produce an output signal from said first detector at the end of the compaction stroke of said pattern plate.

I? I i i i

Claims

1. A mold-making machine comprising, in combination, an open filling frame, a mold flask member disposed in registry with said filling frame, and a pattern member positioned within said filling frame, said filling frame, said mold flask member and said pattern member defining a well for receiving molding sand, means for delivering molding sand to said well, yieldable means for closing off the top of said mold flask membEr to confine the sand within said well between said yieldable means and said pattern member, means for moving said pattern member toward said yieldable means to a predetermined position with respect to said molding flask member, thereby to compact molding sand within said molding flask member against said yieldable means while establishing a desired parting line for the molding sand with respect to said mold flask member, said yieldable means including a chamber filled with fluid which is pressurized in response to compaction of the sand, and means for permitting displacement of said fluid upon attainment of a predetermined pressure therein, thereby to limit the degree of compaction of the molding sand within said molding flask member, means for measuring the quantity of fluid displaced during the stroke of said pattern member, and means for controlling the amount of sand received by said well during the next successive cycle in response to said quantity of fluid displaced.

4. In a mold-making machine of the type including a filling frame adapted to support a mold flask member thereon, a pattern plate moveable within said filling frame between a lowered position and an upwardly extended position for compacting sand within the mold flask member, and means for periodically feeding sand onto said pattern plate, the improvement comprising: a yieldable pressure head moveable into position over the mold flask member and against which sand is compacted by said pattern plate, said yieldable pressure head including a liquid-filled chamber which is pressurized in response to compaction of the sand, and means for bleeding liquid from said chamber upon attainment of a predetermined pressure therein, means for varying the lowered position of said pattern plate in response to the volume of liquid bled from said chamber, said last-mentioned means including a cylinder for receiving liquid bled from said chamber, and a piston in which said cylinder moveable in response to reception of liquid within said cylinder, a first signal generator actuated by said piston and having an output signal proportioned to movement of such piston, a second signal generator actuated by said pattern plate and having an output signal proportional to the stroke of said pattern plate, and means for comparing said output signals to return said pattern plate to a lowered position determined by the difference therebetween.

5. In a mold-making machine of the type including a filling frame adapted to support a mold flask member thereon, a pattern plate moveable within said filling frame between a lowered position and an upwardly extended position for compacting sand within the mold flask member, and means for periodically feeding sand onto said pattern plate, the improvement comprising: a yieldable pressure head moveable into position over the mold flask member and against which sand is compacted by said pattern plate, said yieldable pressure head including a liquid-filled chamber which is pressurized in response to compaction of the sand, and means for bleeding liquid from said chamber upon attainment of a predetermined pressure therein, means for varying the lowered position of said pattern plate in response to the volume of liquid bled from said chamber, said last-mentioned means including a cylinder for receiving liquid bled from said chamber, and a piston in said cylinder moveable in response to reception of liquid within said cylinder, a first detector for producing an output signal when said piston is moved to a predetermined position, a second detector for terminating lowEring motion of said pattern plate, and means for moving said second detector in stepwise fashion to produce an output signal from said first detector at the end of the compaction stroke of said pattern plate.