US3776300A

US3776300A - Apparatus for lifting flasks, molds and patterns

Info

Publication number: US3776300A
Application number: US00223497A
Authority: US
Inventors: W Fismer
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-05-15
Filing date: 1972-02-04
Publication date: 1973-12-04
Anticipated expiration: 1990-12-04

Abstract

An arrangement is disclosed for improving the handling or stripping of the flasks or molds of the type which are used to cast large items such as cast metal plates or frames. A system is provided for lifting the flask or mold vertically from the pattern with assurance that each portion or part is moved at exactly the same rate and amount as every other part.

Description

United States Patent Fism r 1 1 A Dec. 4, 1973 APPARATUS FOR LIFTING FLASKS, 2,499,563 3 1950 Bill 60 97 P MOLDS AND PATTERNS FOREIGN PATENTS OR APPLICATIONS [76] Inventor: Wuhan Verona 1,210,142 2/1966 Germany 164 401 22 F pm 1972 451,555 9/1949 Italy 21 App]. No.: 223,497

Related US. Application Data Division of Ser. No. 224,777, May 15, 1969, Pat. No. 3,643,725.

U.S. Cl. 164/403, 164/227, 254/93 L Int. Cl. .1 B22c 17/00 Field of Search 164/44, 131, 180,

164/181,182,190, 213, 214, 217, 226, 227, 344, 347, 394, 401, 403; 254/89 H, 89 R, 92, 93 R, 93 L; 60/97 E, 97 L Primary Examiner-J. Spencer Overholser Assistant Examiner-John E. Roethel Att0rney-Harold L. Stults [57] ABSTRACT ance that each portion or part is moved at exactly the same rate and amount as every other part.

7 Claims, 1 Drawing Figure APPARATUS FOR LIFTING F LASKS, MOLDS AND PATTERNS This application is a continuation-in-part of copending US. Pat. Application 'Ser. No. 824,777, filed May 15, 1969, now U.S. Pat. No. 3,643,725, the disclosure of which is incorporated herein by reference.

This invention relates to molding operations, and more particularly to hydraulic lifting mechanism for separating a flask, mold or drag from a pattern in a molding operation.

In casting items such as large plates or frames the top of the cavity is formed by the top mold or cope which is lifted away from the pattern at the end of the moldforming operation. Such items and the mold assembly are so designed and constructed as to provide for the proper draw relationship between the mold and the various portions of the pattern. When the dimensions of the top flask or mold are large it is difficult to insure that it will be lifted away from the pattern without tipping or canting. Similarly, the bottom portion of the mold is formed with a drag", i.e., a flask is normally placed on top of the pattern during the mold-forming operation to form the bottom mold pattern or drag which is then lifted from the pattern and inverted to form the bottom of the mold. Alternatively, the flask and pattern are inverted together and the pattern is lifted from the flask or drag. In this case it is necessary to remove the pattern from the mold or drag and, particularly where the pattern is large, it has been difficult to insure that the pattern will be lifted from the drag without tipping or canting.

Accordingly, it is an object of the present invention to provide for the lifting of a mold part, such as a cope, drag or flask from a pattern and the lifting of a pattern from a bottom mold or drag with great precision and with assurance that the element being lifted is lifted at a uniform rate at all points therein.

Another object of this invention is to provide improved means for lifting molds from patterns and patterns from molds while forming molds, copes and drags. Another object is to provide a simple and efficient arrangement for lifting with great precision any item such as a mold or pattern.

The above and other objects, features and advantages of this invention will be apparent in the following detailed description of an illustrative embodiment thereof which is to be read in connection with the accompanying drawing, wherein:

The single FIGURE is a schematic representation of one embodiment of the invention.

Referring to the drawing in detail, the mold pattern i.e., the cope or drag of a mold is schematically represented at 2 and is square in horizontal section. The apparatus of the present invention is provided to lift the flask, cope or drag 2 from a mold pattern (not shown) therebelow. In addition, it is contemplated that the schematically illustrated element 2 may also be a mold pattern, with the apparatus of the present invention lifting the pattern from a bottom mold or drag (not shown) therebelow, after the assembly of pattern and drag has been inverted to a position with the pattern above the drag. In either case, four hydraulic lifting units l2, l4, l6 and 18 are positioned at the four corners of the flask or pattern. It is noted that while these units are shown in alignment in the schematic drawing, they are actually positioned so that their lift plates 4, 6,

8 and 10 are positioned beneath lifting ledges at the four corners of the flask or pattern.

Hydraulic lift unit 12 will be described and it is understood that the other lift units are identical therewith. Unit 12 has a stationary cylinder 20, a piston 22, a piston rod24 and a top cover 26 with a sealing boot 28 abound the piston rod. Extending from the bottom of cylinder is a liquid supply line 30 which extends to the cylinder of a hydraulic operating unit 34, and similar lines extend from the cylinders of

units

14, 16 and 18 respectively to the cylinders of operating units 36,

38 and which are identical with units 34. Each line 30 for the lifting units is connected through a branch line 32 to a balancing valve 33 which will be described more fully below.

Balancing valve 33 has a stationary valve body 90 and a valve rotor 92 which may be turned by a handle 94. When the valve rotor is positioned as shown it closes the ends of branch lines 32. However, when the valve body is turned 180 a cavity 96 in the side of the valve body is positioned in alignment with branch lines 32 so as to interconnect them. Each of

units

34, 36, 38 and 40 has a piston 42 (for clarity unit 38 has been shown in section) which is connected through a piston rod 44 to a push head 46 secured at the free end of the rod. The head 46 of the

cylinders

36, 38 and 40 bear against the outer surface 47 of the piston 42 of

cylinders

34, 36 and 38 respectively. The push head 46 of cylinder 34 is engaged with one end of compression spring 48 that is mounted between head 46 and an end stop 49. The latter is rigidly mounted on a frame member 50 on which

cylinders

34, 36, 38 and 40 are also mounted. In this manner, spring 48 keeps push heads 42 in engagement with the pistons: of adjacent cylinders so that all of the cylinders will act simultaneously, as is hereinafter described.

The piston 42 of cylinder 40 is engaged with a pusher head 51 secured to the end of the piston rod 52 of double acting master cylinder 53.

Lines

56 and 58 are connected to the opposite ends of cylinder 52 so that the piston 54 therein (which is shown in phantom and is connected to rod 52) may be moved back and forth by supplying liquid alternately to the opposite ends of the piston.

Lines

56 and 58 extend to a reversing valve 60 and extending from valve 60 is a line '66 having a flow control valve 68 therein and extending to the outlet of a pump 70. Also extending from valve 60 is a liquid discharge line 62 which extends to the top of a liquid reservoir or sump tank 64. A branch of line 66 is also connected to a pair of

discharge lines

74 and 76 extending to reservoir 64 and having pressure-

control relief valves

78 and 80 therein, respectively.

Valves

78 and 80 are operative to bypass liquid from pump back to reservoir 64 so as to limit the maximum liquid pressure in line 66. As will be explained more fully below, valve 78 is adjusted to a lower maximum pressure than valve and valve 78 is rendered inoperative during the main portion of each operating cycle. Hence, valve 80 is always operative to provide a maximum limit on the pressure in line 66; wherein valve 78 acts only when performing an operating function as is explained below.

Pump 70 is driven by an electric motor 72 and when valve 60 is positioned as shown oil. is delivered through line 66 and valve 68 to valve 60 and thence through line 56 to head 54 of cylinder 53. That drive piston 54 to the left and causes liquid at the left of the piston to flow through line 58, valve 60 and discharge line 62 to the liquid reservoir. When valve 60 is turned 90 from the position shown, the liquid under pressure flows through valve 68 and line 66 to valve 60 and thence through line 58 into cylinder 53 to the left of piston 54. That moves piston 54 to the right and drives liquid from the head of the piston through line 56, valve 60 and discharge line 62 to the liquid reservoir.

The system includes means not shown to maintain the cylinders of

units

34, 36, 38 and 40 and all of the

lines

30 and 32 filled with liquid. Hence, with the ports positioned as shown the movement of piston 54 to the left acts through piston rod 52 and pusher head 51 against piston 42 of cylinder 40, and thus is transmitted through cylinder 40 to

cylinders

34, 36 and 38 against the action of spring 48. As a result, all of the pistons 42 move to the left in their cylinders. With branch lines 32 closed by balancing valve 33, unit 34 forces liquid into the bottom of the cylinder of unit 12 and raises the piston therein so as to exert a lifting force on plate 4. Similarly, each of

units

36, 38 and 40 acts to exert a lifting force through its unit (l4, 16 or 18) to exert a lifting force on its lifting plate (6, 8 or 10). Hence, with the operation just described the supplying of liquid under pressure to the head of cylinder 53 causes flask or pattern 2 to be raised. However, as has been pointed out above, it is important to insure that flask or pattern 2 is lifted the same amount and at the same rate at all places; in this embodiment at each of its corners.

In practice there is play in the operation of each of the

units

12, 14, 16 and 18 and that varies from unit to unit. For example, unit 12 may take up the play and start lifting flask 2 prior to unit 14 at an adjacent corner or prior to unit 16 at the opposite corner. That mode of operation would be unsatisfactory and is avoided in accordance with the present invention. To accomplish that purpose there is an initial tightening" step which precedes the step of lifting the flask. During that tightening step each of the units 12, l4, l6 and 18 is supplied with sufficient liquid under a controlled pressure which moves its piston 22 upwardly so as to press its pressure plate (4, 6, 8 or 10) against its lifting ledge on the flask or pattern. The liquid pressure is not great enough to produce any lifting movement on the flask so that each of units 12, l4, l6 and 18 is moved into lifting position but it cannot move further upwardly.

That initial step is achieved with valve rotor 92 turned to a position with its cavity 96 interconnecting all of the branch lines 32. Hence, all of the

units

34, 36, 38 and 40 act together in parallel to supply liquid at a uniform pressure to all of the

units

12, 14, 16 and 18. Any differences in the operating relationship between one or another of one operating unit and its lifting unit (e.g. 34 and 12) and another are balanced out so that all of the operating units are exerting exactly the same pressure and all of the lifting units are pressing their lifting plates against the flask with the same force. After each of the plates 4, 6, 8 and 10 are engaged with flask or pattern 2, and the play is taken up, valve body 92 is turned to the position shown in the drawing so as to close the interconnection between lines 32; thence, liquid at higher pressure is supplied through line 56 to unit 53 so that its piston 54 moves further to the left, thereby causing the pistons 42 in lifting

units

34, 36, 38 and 40 to move to the left to supply additional liquid to lifting

units

12, 14, 16 and 18 in order to lift the flask or pattern 2 with a uniform motion. Valve 68 is adjusted to control the rate at which liquid is supplied through line 66 to line 56 and that controls the rate at which the flask is raised. .However, each of the lifting units exerts the same lifting pressure at the same rate as all the others and the flask is moved precisely the same distance and at the same rate throughout.

It has been indicated above that

valves

78 and 80 are pressure regulating valves and they are used to maintain the desired pressure of liquid supplied through line 66. Pump 70 operates continuously and is adapted to supply liquid at the pressure necessary to lift the flask or pattern 2. However, valve 78 is adapted to limit the pressure of the liquid supplied in line 66 to the value desired during the initial step of the lifting operation as described above. Hence, during that initial step when valve 33 is rendered inoperative and interconnects lines 32, relief valve 78 is also rendered operative. Therefore, when all of the lifting units are properly positioned during the initial step of a lifting operation, the operating units can no longer move and that prevents piston 54 from moving further in its lifting stroke. As a result, the flow through line 56 stops and the pressure rises in line 66 to the value at which valve 78 opens and all of the liquid from pump 70 is returned through line 74 and valve 78 to reservoir 64.

Valve 80 is a pressure limiting switch which is effective when valve 78 is not operating to limit the maximum oil pressure in line 66 and, therefore, the maximum pressure which is exerted at the lifting units. Hence, if for any reason flask 2 exerts abnormal resistance to the lifting movement, the pressures within the systemrise and are limited by the opening of the bypass valve 80. This valve 80 can also be used to limit the liftin g stroke by the arrival of the pistons 22 to the tops of their cylinders 20. Also, if there is malfunctioning in thesystem, valve 80 opens to prevent damage due to excessive pressures.

The return of the lifting components to their respective positions as shown is effected by turning valve 60 through so that liquid under pressure is supplied from line 66 to line 58 into cylinder 53 at the left of piston 54, and line 56 is connected to line 62 so as to permit the liquid to flow from the right-hand side of the piston. As a result, the pressure applied to

units

34, 36 and 38 is relieved and the pistons 42 therein are returned to the right under the influence of spring 48 which thus acts to keep all of the push heads 46 engaged with their associated pistons. Valve 33 is also turned at this time so that channel 96 connects lines 32 to assure even lowering of

units

12, 14, 16 and 18.

During the initial step, as described above, with lines 32 interconnected by the cavity 96, all variations in the amount of play in

units

12, 14, 16 and 18 and between their lifting plates and flask 2 are taken up and there is an equalization between the

liquid pressure units

34, 36, 38 and 40. This pressure equalization overcomes any variation in the amount of liquid in the various cylinders which would cause an unbalance in the subsequent lifting action. A stable condition is then reached in this initial step wherein pump 70 maintains the constant pressure determined by valve 78 and all of the lifting plates are held against their respective ledges on flask 2 with the same pressure.

Hence, when valve 33 is turned to disconnect lines 32 and valve 78 is rendered inoperative by manual or automatic means, there is an immediate increase in the pressure in line 66. That causes liquid to flow through line 56 into cylinder 53 so as to move piston 54 to the left. That rate of movement is controlled by the adjustment of valve 68. The movement of piston 54 causes a corresponding movement of each of the pistons 42 and, the liquid not being compressible, there is a corresponding lifting movement by each of the pistons 22. Hence, the lifting action is immediate and uniform and the rate of lifting may be increased or decreased by ad- I justing valve 68.

As indicated above, the flask is lowered into place by the reverse action, and during the lifting and lowering, valve 80 provides control to insure against excessive pressure conditions.

It is thus seen that the operation is simple and dependable and that flask or pattern 2 is moved with great precision at all times and that the above and other desirable objects are accomplished.

Although an illustrative embodiment of the present invention has, been described herein with reference to the accompanying drawing, it is to be understood that the invention is not limited to that precise embodiment and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of this invention.

What is claimed is:

1. An apparatus for separating the elements of a molding process including a mold element and its pattern comprising, in combination, a plurality of lifting units each of which has a cylinder and a piston mounted therein and which is positioned and related to the mold and pattern so that the supplying of liquid under pressure to a lifting unit moves a lifting element of the lifting unit into lifting engagement with one of said mold element and pattern and upon the further supplying of liquid thereto said lifting unit cooperates with the other lifting units to produce a total lifting force which separates the mold and pattern, a plurality of liquid-pressure units each of which comprises a cylinder and a piston mounted therein which is connected by liquid passage means to the cylinder of one of said lifting units whereby the relative movement of the piston and cylinder of the liquid-pressure unit causes liquid flow between the liquid-pressure unit and the interconnected cylinder of the corresponding lifting unit, means for selectively interconnecting and disconnecting the cylinders of said lifting units whereby when said cylinders are interconnected all of said lifting units are operated in parallel by all of said liquid pressure units to simultaneously control the lifting forces of said lifting units to a value which is less than that required to produce said total lifting and the separating movement and at which said lifting elements are moved into operating relationship, and means for producing simultaneous lifting of said one of said mold and pattern elements by said lifting units when said selective interconnecting and disconnecting means disconnects said cylinders whereby each of said lifting units receives liquid from only one of said liquid pressure units to separate said mold and pattern elements.

2. Apparatus as described in claim 1 wherein said means for producing simultaneous movement includes a main unit which comprises a main cylinder and a main piston and which is operative to impart said relative movement to said liquid-pressure units, and means to supply liquid to said main cylinder to produce relative movement between said main cylinder and said main piston.

3. Apparatus as described in claim 2 wherein said means to supply liquid comprises, a motor-driven liquid pump, a liquid reservoir from and to which liquid is delivered, valve means to connect liquid under pressure from said pump alternately to opposite ends of said main cylinder and pressure relief valve means to limit the pressure of the liquids supplied by said pump.

4. Apparatus as described in claim 3 wherein said pressure-relief valve means comprises two valves one of which is operative to limit the liquid pressure to the value required to move said lifting units into operating relationship with said one of said mold and pattern elements and the other of which provides a maximum liquid pressure at all times.

5. An apparatus for separating a pair of adjacent elements comprising, in combination, a plurality of lifting units each of which comprises a cylinder and piston and is operative to exert a lifting force when liquid is supplied to the cylinder, a plurality of piston-cylinder units corresponding in number to said lifting units and connected respectively thereto to supply lifting liquid under pressure, interconnecting valve means which is operable to connect and disconnect the cylinders of said lifting units whereby all of said lifting units may be operated in parallel during an initial step and may then be disconnected and operated independently by their respective piston-cylinder units, a common operating unit for all of said piston-cylinder units including a main double acting piston-cylinder unit having a cylinder to which liquid is supplied to impart simultaneous movement to said piston-cylinder units, pump means to supply liquid under pressure to operate said main piston-cylinder unit, and pressure control means to regulate the pressure of liquid supplied by said pump means.

6. Apparatus as described in claim 5 wherein the pressure control means includes means to limit the pressure of liquid from said pump means to a value which moves said lifting units into operating relationship without producing a lifting action while said lifting units are interconnected and to provide an increase in pressure when said lifting units are not interconnected whereby said units are first moved into operating relationship at one pressure and the pressure is then raised to produce simultaneous lifting by said lifting units.

7. Apparatus as described in claim 6 wherein said piston-cylinder units are located in axial alignment with each other and with said main piston-cylinder unit, and means operatively interconnecting said piston-cylinder units with each other and with the piston of said main piston-cylinder unit whereby movement of the piston in said main piston-cylinder unit imparts simultaneous movement to the cylinders in said piston-cylinder units. k 4:

Claims

7. Apparatus as described in claim 6 wherein said piston-cylinder units are located in axial alignment with each other and with said main piston-cylinder unit, and means operatively interconnecting said piston-cylinder units with each other and with the piston of said main piston-cylinder unit whereby movement of the piston in said main piston-cylinder unit imparts simultaneous movement to the cylinders in said piston-cylinder units.