Cementitious product making system with product height gauging mechanism

A concrete product making machine having a product forming mold with a cavity for receiving cementitious material; support surfaces such as pallets on which the formed products are supported; a transfer device by which "green" products or blocks are removed on their pallets from the vicinity of the mold; a block height gauging device, downstream of the mold, for gauging the height of the products by gauging the distance from the top surfaces of the pallets to the top surfaces of the products; and mechanism controlling the volume of material delivered to the mold accordingly.

In the manufacture of concrete building blocks, it is important for a 
variety of reasons that the blocks be uniform in size and density. In the 
subsequent laying of blocks, height of the blocks becomes particularly 
important because the blocks must be laid in level courses. 
In one block making machine which has been proposed, the heights of the 
blocks were gauged from the under surfaces of the pallets on which the 
blocks were supported. In such a machine, the thickness of the pallet 
affects the heights measured. For example, a block formed on a thick 
pallet will appear to have less height than a block formed on a thinner 
Accordingly, efforts were made to develop apparatus for gauging the height 
of the block independently of pallet thicknesses. One such machine 
includes apparatus for measuring the block height by gauging the distance 
from the top of the pallet while the mold is being vibrated. In this 
machine the vibration introduces another variable which affects the 
heights measured and negates some of the advantage resulting from gauging 
the block height independently of the pallet. Accordingly, it is an 
important concept of the present invention to provide a block-engaging 
apparatus, connected with mechanisms for controlling the volume of 
material delivered to the mold, which gauges the heights of the blocks 
formed by measuring the distance from the top of each block supporting 
pallet to the tops of the blocks thereon at a time when the blocks are not 
being vibrated. 
Other objects and advantages of the present invention will become apparent 
to those of ordinary skill in the art as the description thereof proceeds. 
BRIEF SUMMARY OF THE INVENTION 
A concrete product or block manufacturing machine with height gauging 
apparatus for gauging the height of a "green" block supported on a pallet 
by gauging the distance between the top of a block supporting pallet and 
the top of the product including: a frame; a support vertically movable on 
the frame between a raised, inoperative position and a lower, pallet top 
sensing position at a level dependent upon the level of the top of the 
pallet; a block top sensor mounted on the support for vertical movement 
relative thereto, to a level dependent upon the height of the formed 
block, and mechanism controlled by the sensing mechanism for controlling 
the volume of material delivered to the mold.

Referring initially to FIG. 3, a block forming machine is schematically 
designated 10 and is of a construction more particularly illustrated in 
either of the present assignee's U.S. Pat. Nos. 2,957,222 or 3,679,340, 
which are incorporated herein by reference. A concrete block forming 
machine 10 includes a vibratile mold box 12, open at its upper and lower 
ends or sides and vibrated by an eccentric shaft device E. A pallet 
conveyor, generally designated 16, is provided for moving block supporting 
pallets 18 successively into a position at the under side of the mold box 
12 as described more particularly in the referenced patents. Also provided 
is a vertically movable pallet support frame 17, situated between the 
belts of conveyor 16, to move the pallet 18 upwardly off the conveyor 16 
into engagement with the underside of mold box 12. A cementitious material 
feed box 14 is slidably movable in a to-and-fro path between a remote or 
removed material receiving position and a material discharge position, 
over the mold box 12, in which it delivers cementitious thereto. 
As the feed box 14 is withdrawn, the mold box 12 is vibrated for a 
predetermined time via vibrating mechanism 13, to cause the cementitious 
material to settle and a stripper head, generally designated 20, is 
thereafter lowered into engagement with the vibrating material in the mold 
box 12 to pack the material into the mold cavity and form the block to its 
proper height. When the block is formed to the proper height, the 
vibration is interrupted and the stripper head 20 will continue to move 
the side-by-side blocks B (FIG. 1), downwardly toward the underlying 
pallet conveyor 16. 
As the stripper head 20 is moved downwardly relative to the mold box 12 to 
strip the side-by-side blocks B from the mold box, the pallet frame 17 is 
concurrently moved downwardly to deposit the pallet 18 on the underlying 
conveyor 16. The conveyor 16, as indicated, includes a pair of laterally 
spaced apart belts 22, trained around end rolls 24, and supported along 
their length by idler rolls 26 journaled, via shafts 28, on a frame, 
generally designated F. 
Block height gauging apparatus (FIG. 1), is provided at a block height 
sensing station 31, downstream of the block making machine 10, and 
includes a pair of gauging devices, generally designated 29, on opposite 
sides of the conveyor 16 between belts 22 for measuring or gauging the 
height of the side-by-side blocks B and indicating any deviation from a 
predetermined standard. The block height gauging apparatus 30 includes a 
pair of frame supported, vertically disposed, side bars 32 mounting 
longitudinally extending, horizontally disposed supports 34. 
Mounted on each horizontally disposed support 34 is a horizontally 
disposed, double acting, solenoid actuated, fluid pressure operated 
cylinder 38 including an axially movable piston rod 39, having opposite 
end portions 39a and 39b extending axially beyond opposite ends of the 
cylinder 38. Mounted to span opposite ends of each piston rod 39 is a 
laterally movable, inverted, U-shaped mounting bracket 40. A coil spring 
42 is disposed on the inner end 39a of the piston rod 39 and reacts 
between the cylinder 38 and the bracket 40 to bias the piston rod 39 
inwardly to the laterally inner position illustrated at the left side of 
FIG. 1. Each piston rod is retractible to the position illustrated at the 
right side of FIG. 1. 
Mounted on each bracket 40 for lateral movement therewith, is an upstanding 
channel 44 provided with internally disposed guides 46 guiding a 
vertically movable roller supporting rod 48. Mounted at the lower end of 
the guide rod 48 is a bracket 50, journaling a pallet engaging roller 52. 
Longitudinally convergent block centering rails 41 are fixed to the 
inverted, U-shaped mounting brackets 40 on opposite sides of the conveyor 
for centering the block supporting pallet 18 as it moves downstream in the 
direction of the arrow a (FIG. 2) to the block height sensing station 31. 
Since the successive pallets 18 are not all exactly of the same thickness, 
it is important that the height of the blocks B be gauged from the top 
surface 18a of each pallet, and not the bottom thereof because deviations 
in the thickness of the pallets 18 will introduce error into the guaged 
height. For this reason, the pallet sensing rollers 52 engage the top 
surface 18a of each pallet 18. A guide bracket 54 is mounted on each 
upstanding channel 44 and includes a vertical guide opening 56 for 
receiving a guide pin 58 which is fixed to the vertically movable roller 
mounting rod 48. Also, a stop 60 is fixed to the top of each rod 48 for 
engaging guide 46 and limiting downward movement. 
Apparatus is provided for moving the roller mounting rods 48 from the 
lowered positions, illustrated in FIG. 1, to raised positions, removed 
from the pallet 18, and comprises a pair of double acting, solenoid 
actuated, fluid pressure operated cylinders 62, mounted on the side rails 
32 and including piston rods 64 having at least portions thereof axially 
aligned with the guide rods 48. A slight gap g is provided between the 
adjacent ends of the rods 64 and 48 when the cylinder rods 64 are 
retracted and the rollers 52 engage the top of a pallet. 
Fixed to each roller mounting rod 48 at each side of the conveyor is a 
horizontally supported, mounting bar 66 carrying sensing apparatus, 
generally designated 68, which is in the path of and engages the tops of 
the blocks B as they move in a forward path of travel represented by the 
arrow a. The sensing apparatus 68 includes a housing 69 above each block B 
mounting a variable resistance electrical device 70, such as a rheostat or 
potentiometer having a linear resistor 71 and a resistor engaging wiper 
arm 72 (FIG. 3), mounted on a vertically movable actuating rod 74 which 
may be normally biased downwardly by means such as a leaf spring 76. 
Mounted on the underside of each housing 69 is a vertical sleeve 78 
receiving a roller mounting rod 80 having a clevis 82 fixed to its lower 
end to journal a block engaging roller 84. A guide pin 86, fixed to the 
rod 80, is received in a slot 88 on the sleeve 78 for guiding the rod 80 
as it moves vertically. A stop pin 90 is fixed to the upper end of each 
rod 80 to engage housing 69 and maintain it in suspended position. 
THE CONTROL CIRCUIT 
A control system for controlling the apparatus illustrated in FIGS. 1 and 2 
is illustrated in FIG. 3, and includes a pair of lines L1 and L2 connected 
across a suitable source of direct current electrical power. The resistor 
70 of each block height gauging device 27 is connected in a typical bridge 
circuit, generally designated 92, including resistors 93, 94 and 95 
connected as usual in bridge circuit relation across lines L3, L4, L5 and 
L6. The movable potentiometer arm 72, which is mechanically connected to 
the block engaging roller 84 via the rod 80 is also connected electrically 
to the line L5. More specifically, and as illustrated in FIG. 3, line L3 
is connected between line L1 and the junction of the resistors 94 and 95; 
line L6 is connected between the line L1 and to the junction of the 
resistors 93 and 70. The opposite sides of a direct current motor M, for 
controlling the mount of material delivered to the mold box, are connected 
to lines L4 and L5 which are connected to the junction of the resistors 93 
and 94, and to the junction of the resistors 70 and 95, respectively. The 
motor M, which pivots a discharge gate 96 between the solid and broken 
line positions shown in FIG. 3, is driven in opposite directions depending 
upon the condition of unbalance of the bridge circuit 92. The speed of the 
motor M is dependent upon the degree of unbalance. If the circuit 92 is 
balanced, the motor M is not driven. The unbalance is, of course, 
dependent upon the position of the wiper arm 72. The gate 96, which is 
connected to the motor M by suitable linkage (not shown), selectively 
tends to close the outlet portion of the hopper 14 and thus controls the 
amount of material fed to the mold 12. Provided to reciprocate the feed 
hopper 14 (and gate 96) is a double acting, fluid operated, solenoid 
controlled power cylinder 97 which, between each block forming operation, 
removes the hopper 14 to the right in FIG. 3, to a position under a 
material supply device (not shown) and then returns it to the mold feeding 
position in which it is shown in FIG. 3. Alternatively, or conjunctively, 
the motor M could be connected to a screw device mounting stripper 20 to 
adjust its position relative to the power cylinder or the like, which 
moves it, and thereby vary the vertical position which it assumes while 
the mold is being vibrated. 
A proximity switch 101 (FIGS. 1 and 2) is provided in the path of the 
pallets 18 to indicate that a pallet is at the block height sensing 
station 31 and includes normally open contacts 104 (line L7), normally 
open contacts 105 (line L5) and normally closed contacts 106 (line L8). 
The contacts 104 (line L7) are connected in series with a solenoid 62a 
which directs fluid to each cylinder 62 to retract the piston rods 64 and 
permit the roller support rods 48 and the pallet engaging rollers 52 to 
lower to the block engaging position illustrated in FIG. 2. The switch 106 
(line L8) is connected in series with a solenoid 62b which, when 
energized, will direct fluid to each cylinder 62 in such a direction as to 
raise its piston rod 64 and move the superjacent roller support rod 48 and 
roller 52 to a predetermined position above the level of the pallet 
surface 18a when no pallet is at the sensing station. 
THE OPERATION 
Cementitious material is supplied to the feed box 14, which is moved to a 
position over a mold 12 having a pallet 18 held against its underside by 
the pallet frame 17, to discharge the cementitious material into the mold 
12. The feed supply box 14 is then withdrawn by cylinder 97 and the 
stripper head 20 is lowered to compact the material in the mold 12 while 
the mold 12 is being vibrated. The motor which drives eccentric E is, as 
usual, connected with a circuit line which includes a contact carried by 
the stripper head and a vertically aligned contact carried by the mold 
box. When the stripper head contact, due to compaction of the material, 
engages the mold box contact, the circuit to the motor driving eccentric E 
is broken. Thus, when the desired compaction occurs, (as gauged by the 
contacts engaging) mold box vibration is interrupted and the stripper head 
20 continues to move downwardly to move the pallet 18 and pallet support 
frame 17 downwardly until the pallet 18 is supported by the conveyor 16 
which forwardly conveys the blocks B downstream of the mold 12 in the 
direction represented by the arrow a, to the block height sensing station 
31. 
The piston rods 64 are normally extended to lift the roller supporting rods 
48 and the rollers 52 to positions above the level of the pallet surface 
18a. When the proximity switch 101 is tripped to indicate that a pallet is 
in position at the gauging station 31, the solenoids 62a are energized to 
lower the piston rods 64 so that the rods 48 and rollers 52 will lower 
into engagement with the top pallet surface 18a. If the blocks B are 
undersize, they will not move the rollers 84 upwardly. The wiper arms 72 
will remain in their lowermost positions to unbalance the circuit in one 
direction and drive the motor M in such a direction as to pivot the blade 
96 in a direction so that additional material will fall into the mold on 
the subsequent block formation cycle. 
If the blocks B are of the proper predetermined height, they will force the 
rollers 84 and piston rods 80 upwardly to push the rods 74 and the wiper 
arm 72 upwardly to the position in which the circuit will remain balanced 
and the motor M will not be driven. A switch 105, provided in line L4, is 
only closed when the switch 101 is actuated so that the motor M is not 
driven when blocks B are not in position at the gauging station 31. If 
blocks B are oversize, the rollers 84 will move the slider 72 to the top 
of resistor 70 to unbalance the bridge circuits 92 in the opposite 
direction and drive the motor M in the opposite direction to tend to close 
the gate 96 and permit less cementitious material to flow into the mold 12 
on the subsequent block forming cycle. A galvanometer 110 is connected in 
parallel with the motor M to provide a visual indication to the operator 
of the degree of deviation of the height of the block B from a 
predetermined height. The apparatus is, as described, self-correcting to 
correct any deviation in the height of the block being formed. 
It is to be understood that the drawings and descriptive matter are in all 
cases to be interpreted as merely illustrative of the principles of the 
invention, rather than as limiting the same in any way, since it is 
contemplated that various changes may be made in various elements to 
achieve like results without departing from the spirit of the invention or 
the scope of the appended claims.