US3888453A

US3888453A - Top block stop for applying a longitudinal force to the top block of a pressure casting mold

Info

Publication number: US3888453A
Application number: US462612A
Authority: US
Inventors: Lyman Wood Jeffreys
Original assignee: Amsted Industries Inc
Current assignee: Amsted Industries Inc
Priority date: 1974-04-12
Filing date: 1974-04-12
Publication date: 1975-06-10
Anticipated expiration: 1992-06-10
Also published as: CA1036318A; DE2515394B2; DE2515394A1; JPS50136226A; IT1035275B; SE403059B; SE7504200L

Abstract

In an adjustable slab mold having side, end, top and bottom blocks, a top block stop is positioned at one end of the top block opposite the riser opening. The top block stop is engagable with the side blocks and has means for applying a force to the riser end of the top block which is directed along the longitudinal axis of the top block. The magnitude of the engaging force applied is equal to or less than the static frictional force existing between the sides of the top block and the side blocks of the mold assembly. Thermal forces on the top block stop caused by metal heating the top block are greater than the engaging force.

Description

United States Patent Jeffrey's i 1 June 10, 1975 TOP BLOCK STOP FOR APPLYING A 3.646.991 3/1972 Jeffreys I63/342 amiss; 7 1972 Peck i, 249/82 LONGITUDINAL FORCE TU THE TOP BLOCK ()F A PRESSURE CASTING MOLD Primary Examiner-Francis S. Husar Ash's/an! Examiner-David S. Safran Attorney. Agent or FirmAndrew J. Bootz; Ralph M Faust; Fred P. Kostka [57] ABSTRACT ln an adjustable slab mold having side end. top and bottom blocks, a top block stop is positioned at one end of the top block opposite the riser opening. The top block stop is engagable with the side blocks and has means for applying a force to the riser end of the top block which is directed along the longitudinal axis of the top block The magnitude of the engaging force applied is equal to or less than the static frictional force existing between the sides of the top block and the side blocks of the mold assembly Thermal forces on the top block stop caused by metal heating the top block are greater than the engaging force 6 Claims, 7 Drawing Figures SHEET PATENTEBJUH 10 1915 TOP BLOCK STOP FOR APPLYING A LONGITUDINAL FORCE TO THE TOP BLOCK OF A PRESSURE CASTING MOLD SUMMARY OF THE INVENTION The invention relates to improvements in permanent slab molds and more particularly to improvements in a permanent slab mold having a plurality of cooperating parts.

The mold herein referred to is of type described in US. Pat. No. 3.340.926. which is normally filled from the bottom by pressure casting to cast molten metal into slabs. blooms and billets. In general each mold has opposed movable side blocks that may be engaged with a front. rear. bottom and top block to define a casting cavity. A plurality of individually adjustable screws generally support the top block and are treadedly connected to an equal number of support arms. The arms are rigidly secured at one end to a side block and later ally movable therewith. Different heights of the casting cavity may be selectively defined by adjusting the screws to vary the height of the top block.

One of the difficulties encountered in the use of such molds is the fragile nature of the graphite blocks. particularly the top block, which may often require replacement because of chipping or breaking.

Metallic top blocks. composed of materials such as cast iron or steel, have been proposed as an answer to the problems stated above. The use of metallic blocks. however. creates the additional difficulty of thermal expansion. Thermal expansion of the top block results when the top block is exposed to the extremely high temperatures upon the introduction of molten metal into the mold cavity. As a result of the top block being relatively long and narrow most of the expansion occurs along the longitudinal axis of the top block. Inherently, the top block has a tendency to expand in both directions along its longitudinal axis away from the midsection. However, it is only expansion in the forward direction; toward the riser which presents a problem inasmuch as shifting in this direction can cause cracks in the casting in the area of the riser thereby resulting in a defective product which cannot be properly rolled.

In the past many arrangements were tried to eliminate forward expansion. however, most arrangements relied on stops that were located above the top block and as close as possible near the back of the riser. has much as the forces that were applied to the top block when using such arrangements were not in line with the forces resulting from the thermal expansion, the prior stops could not adequately stop the shifting or expanding of the top block in the immediate area of the riser.

Accordingly, an object of the present invention is to provide an improved top block stop for use in conjunction with the mold described above; which applies a restraining force to the top block which is in line with the forces resulting from thermal expansion.

These and other objects and advantages of this invention will become apparent from a reading of the following detailed description of this invention when taken in conjunction with the accompanying drawings wherein:

DESCRIPTION OF THE DRAWINGS FIG. I is a semidiagrammatic view of an adjustable slab mold;

FIG. 2 is a partial cross-sectional view in elevation of the mold apparatus incorporating the structure of the present invention;

FIGv 3 is a transverse cross-sectional view taken through section line 3-3 of FIG. 2:

FIG. 4 is an elevational view of a top block stop and shift assembly secured to a side block of the slab mold;

FIG. 5 is a fragmentary top view of the top block shift assembly illustrated in FIG. 4; and

FIG. 6 is a transverse cross-sectional view of the top block stop taken along section line 66 of FIG. 4'.

FIG. 7 is a cross-sectional plan view of the top block stop taken along section line 7-7 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Describing the invention in detail and referring to the drawings, FIG. 1 schematically illustrates a slab mold. generally designated I0, comprising two side blocks [2 and I4 (only one shown in FIG. I), a top block 16 having a projecting arm 18, a bottom block 20, a rear end block 22, and a front end block 24. A riser cavity 26 is defined by the end block 24, projections (only one of which is shown) on the side blocks 12 and I4 and the arm 18. All of the blocks. when in position. form a mold cavity 28 having an inlet gate 30 through which molten metal may be forced into the mold. Various means (not shown) are used to move the blocks into and out of engagement and to maintain them in their proper position during casting.

Attention is now directed to FIGS. 2 and 3 which il lustrate in more detail the arrangement described above. As may be seen the top and

bottom blocks

16 and 20 are preferably substantially the same length as the

main side blocks

12 and 14. The bottom block 20 extends below the main side blocks I2 and [4 throughout most of its length, but it has a reduced end portion 32 which is flush with the lower surface of the main side blocks 12 and I4. The bottom block 20 normally remains fixed on a support rail 34 which in turn is supported by transverse beams 36 which are part of the main frame 38.

The top block 16 is supported by a plurality of hangers or supports 40 which are adjustable in order that the position of top block 16 with respect to the

main side blocks

12 and 14 may be adjustable for different sizes of slabs, etc. Further details of the mounting and adjustment of the top block 16 and

side blocks

12 and 14 will be discussed below.

The top, bottom and rear end blocks are selected as to size from the standpoint of the thickness of the slab to be cast. For example, customary slabs may be 5, 6 or 7 inches in thickness and for each of these thicknesses. a corresponding set of blocks is utilized in the mold.

The rear end block 22 is formed of graphite or steel and it is provided on its upper portion with a vent 42 which will permit gas to escape therethrough durin g the pouring of molten metal into the assembled mold 10. It should be understood that during the pouring operation the mold I0 is positioned with the inlet gate 30 over the pouring tube of the ladle (not shown). The mold 10 is slightly tilted by raising the rear end thereof with a jack (not shown) thus allowing the entire mold 10 to pivot on trunnions 44. Tilting the mold provides for up-flow of the molten metal in all portions of the mold; in keeping with preferred pressure pouring practice. the mold is tilted about 3 degrees. The rear block 22 is provided with a backing plate 46 secured by conventional means. such as screws (not shown). to the block 22. The plate 46 provides means for attaching the adjusting mechanism. shown generally at 48, to the rear end block 22.

The preferred specific means for mounting the main side blocks 12 and 14 may best be seen in FIG. 3. The main side blocks 12 and 14 are mounted in flasks 50 which are opposite and symmetrical and otherwise substantially identical. Each flask 50 includes a lower horizontal portion 52 under the corresponding side block for supporting the latter, and a horizontal top portion 54 for supporting the top of the block and for other purposes to be referred to hereinbelow. Each flask 50 includes a main vertical portion 56 which is made up of a plurality of horizontal and vertical members. The flasks 50 are each mounted on a carriage 58 (one of which is shown) which is capable of moving transversely on the main frame 38.

Mounted on the main frame 38 are a plurality of abutment members 60 which are spaced longitudinally and on both sides of the mold 10. These abutment members take the form of rigid posts and provide support for power means 62 which are preferably hydraulic cylinder ram devices 64. Each abutment member 60 has a cylinder 64 mounted thereon and a piston 66 extends from each cylinder 64 for engagement with the main vertical portion 56 of the flask 50.

Upon actuation of the power devices 64 and corresponding extension of the pistons 66 therein. the flasks 50 and the side blocks 12 and 14 mounted therein are moved toward each other to a closed position. Upon actuation of the hydraulic cylinder ram devices 64 in the opposite direction the pistons 66 retract and draw the flasks 50 and side blocks 12 and 14 apart, and thus open the mold.

FIGS. 3 to illustrate an arrangement wherein a top block shift generally designated 68, comprises three bases generally designated 70 that may be mounted relative to side blocks 12 or 14 of the mold on the horizontal top portion 54 of flask 50. The bases 70 are interconnected by support platform 72.

Vertical lifters generally designated 74, are mounted along platform 72. The lower end of each screw 76 of each lifter 74 may be connected to a support beam 78 that is secured to the top of top block 16.

As illustrated in FIG. 3, each base 70 may include a vertical axle 80 that may be rigidly mounted at its lower end in an opening 82 in a frame 84 that is secured to the upper horizontal portion 54 of flask 50. The axle is mounted in upper and lower bearings generally designated 86 and 88, the outer race of which is in contact with the upper and lower portions respectively of cavity 90 of housing 85.

A second cavity 92 similar to cavity 90 also located in housing 85 has an axle 94 mounted therein in a man ner similar to the mounting of axle 80. The upper end of axle 94 is rigidly secured to an arm 96 connected to platform 72. Bearings generally designated 98 and 100 are mounted in cavity 92 in a manner similar to bearings 86 and 88 to permit relative rotational movement between axle 94 and housing 85.

A hydraulic or pneumatic device generally designated 102 having a ram 104 pivotally connected to the back of one of the housings 85 and a cylinder 106 pivotally connected to frame 84 may be used to rotate housing 85 relative to axles and 94. Retraction of ram 104 results in pivotal movement of housing about axle 80. Such movement swings platform 72 laterally away from side block 12 and longitudinally away from riser 26. The side blocks 12 and 14 may then be further separated by known means as previously described.

FIGS. 47 best illustrate the top block stop generally designated 108 which is mounted on the support beam 78 of the slotted steel top block 16.

The top block 16 is connected to support beam 78 of the riser end by pin 200 preventing longitudinal as ell as vertical movement of top block relative to the support beam. Remaining pins 201 are in slotted holes that connect the top block to the support beam in a vertical direction but allow longitudinal movement.

It should be understood that the top block stop 108 could be integral with the top block support beam 78 and the term *mounted" is meant to include this alternate embodiment.

The top block stop 108 has a housing 110 which is illustrated as an integral part of the top block support beam 78. The longitudinal axis XX of the housing 110 is generally parallel to the top block 16. In the rear portion 112 of the housing 110 is positioned a hydrau lic cylinder 114 which is capable of movement in the direction of the longitudinal axis XX of the housing 110. The front portion 116 of the housing 110 has :1 laterally extending opening 118 which is intended to receive a transversely extending stop beam 120: also capable of movement along the longitudinal axis XX of the housing 110. Retention of the stop beam in the opening 118 is accomplished by means of a retaining bolt 122 which extends upwardly through a longitudinal slot 109 in the housing 110 and into the lower surface 124 of the stop beam 120.

Affixed to the housing 110 is a pilot operated check valve 126 to which a hydraulic fluid supply (not shown) may be connected. The purpose of the pilot operated check valve is to completely seal the fluid in the hydraulic cylinder and release the fluid from the cylinder. Activation of the hydraulic cylinder 114 forces the pis ton 128 toward the rear surface 130 of the stop beam 120; upon engagement thereof the stop beam 120 is forced forward in the opening 118 until the forward surface 132 of the stop beam 120 engages the flask plates 134 mounted on each of the flasks 50. The stop beam 120 rotates about retaining bolt 122 to compensate for nonalignment of the flask plates 134.

When the pressure in the hydraulic cylinder 114 is released both the stop beam 120 and the piston 128 are moved toward the rear of the housing 110 by a pair of return springs 121 which are positioned within a pair of pockets 123 in the stop beam 120. The return springs are located on either side of the retaining bolt 122 and are parallel to the longitudinal axis XX of the housing 110. One end of each spring is in engagement with the housing 110 of the top block stop 108 while the other ends of the return springs 121 are seated within the pockets 123 of the stop beam 120.

The return of both the stop beam 120 and piston 128 to their original position by the return springs 121 in sures that the forward surface 132 of the stop beam 120 will be clear of the flask plates 134 thus eliminating any problem of interference therewith when the side blocks 12 and 14 are being moved.

Thus it can be seen that as the force of the hydraulic cylinder H4 increases and the slack in the system is removed a substantial force is applied by the stop beam 120 to the flasks 50 thereby creating a reactive force on the top block [6 which is directed away from the riser cavity 26 and toward the top block stop I08. This reactive force is directly in line with the thermal forces which are created in the top block 16 during the pouring operation and thus effectively prevents shifting of the top block 16 in the area of the riser cavity 26.

The magnitude of the engaging force applied by the hydraulic cylinder 114 is equal to or less than the static frictional force existing between the sides 136 of the top block 16 (one side of which is shown in FIG. 4) and the front cavity defining surfaces [38 and 140 of the side blocks 12 and 14 respectively. When molten metal contacts the top block 16, said top block expands thermally away from pin 200. The thermal force causing the expansion exerts a load on hydraulic cylinder 114 that is greater than said engaging force. Pressure in the fluid sealed in hydraulic cylinder [14 by pilot check valve 126 increases to compensate the said thermal force. Clearly, it may be seen by those skilled in the art that the force applied by the hydraulic cylinder 114 will vary from one mold assembly to another due to the variance of certain parameters that are dependent upon such things as the size of the casting apparatus.

The coefficient of friction that exists between the top block 16 and the side blocks 12 and 14 vary with the composition of the blocks used as well as with any surface coating that may have been applied to any of the blocks. However, having taken these factors into consideration the coefficient of friction may be determined in a known manner familiar to those skilled in the art.

The frictional force existing between the side blocks 12 and 14 and the top block 16 will also vary in direct proportion to the normal force applied to the engaged surfaces. The magnitude of the normal force is equivalent to the force applied to the flasks 50 by the power means 62. In general, this force will be equal to the hydrostatic pressure resulting from the column of molten metal which will be poured into the mold cavity 28. Once the above-mentioned quantities have been determined for a given mold assembly the force to be exerted by the top block stop 108 may be calculated using relationships well-known to those skilled in the art.

Prior to the pouring of the molten metal into the mold the following sequence of stops are necessary. The rear end block 22 is positioned, by means of the adjusting mechanism 48, a given distance from the front end block 24. Thus the length of the slab to be cast is established. Next the side block 12 is then moved toward the bottom block on carriages 58 by power means 62 until the bottom block 20 is engaged as well as the rear end block 22. Top block 16 and front block 24 are carried with side 12. The top block 16 is then lowered by means of the top block shift 68 until it engages the upper end 142 of the rear end block 22. When so positioned the height of the slab to be cast is determined. Side 14 is now moved to engage top, bottom, back and front blocks 16, 20, 24 and 22 respectively. Power means 62 continues to apply force to the flasks 50 until the applied force is equal to the hydrostatic pressure of the molten metal when poured into the mold cavity 28. After the above sequence has occurred the hydraulic cylinder 114 of the top block stop 108 may be activated thereby applying an engaging force to the top block l6 which is equal to or less than the static frictional force existing between the top block 16 and the side blocks 12 and 14 when the normal force is equal to the force applied by the power means 62.

After the metal has solidified in the mold reversal of the above steps is required before the slab may be removed. The pressure is released in the hydraulic cylinder 114 of the top block stop 108 as a result the stop beam is forced away from the flask plates [34 by the return springs 12! and moved toward the rear of the opening 118 in the housing X10. The side blocks [2 and 14 are then moved apart and the vertical lifters are actuated as previously described, to lift the top block 16 upwardly away from the cast slab (not shown) in cavity 28.

It is to be understood that the foregoing description and the accompanying drawings have been given only by way of illustration and example. It is also to be understood that changes in form of the elements, rearrangement of parts, and substitution of equivalent elements, which will be obvious to those skilled in the art, are contemplated as within the scope of the present in vention.

What is claimed is:

1. In a mold apparatus having side blocks laterally movable toward and away from each other and a plurality of movable inner blocks, including a longitudinally extending top block having first and second ends, said top block being positioned between the side blocks and engaged therewith, the side blocks and the inner blocks defining together a casting cavity and also a riser cavity at the first end of said top block, a top block support beam connected to said first end of said top block, a top block stop connected to said top block support beam at said second end of said top block, said top block stop having means reacting against a portion of said mold apparatus for applying an engaging force to said first end of said top block in a longitudinal direction away from said riser cavity.

2. The mold apparatus set out in claim 1 wherein said top block stop is engagable with said side blocks.

3. The mold apparatus set out in claim 2 wherein said engaging force applied to said top block is equal to or less than the static frictional force existing between said top block and said side blocks.

4. The mold apparatus set out in claim 3 wherein said engaging force is less than the thermal force created in said top block resulting from the introduction of molten metal into said mold apparatus.

5. The mold apparatus set out in claim 3 wherein said force applying means includes an hydraulic cylinder.

6. The mold apparatus set out in claim 4 wherein said hydraulic cylinder is operated by a pilot check valve.