Apparatus for sensing and ejecting bricks of improper size

[57] ABSTRACT

Raw bricks are cut from an extruded column of clay and conveyed in single file past a sensing means including an inclined light path extending between a light source and a plurality of photocells arranged linearly along one side of the conveyor. The light path cuts through one corner of each brick, and the photocell arrangement measures the thickness thereof. The sensing means is adapted for use with both “standard” and “utility” size bricks and also effective to determine undersize as well as oversize bricks. A brick ejecting means is mounted adjacent the conveyor, immediately succeeding the photocells, and is responsive to the sensing means to eject prescribed bricks of improper thickness. The ejecting means includes a pivotal kickoff lever attached to the free end of an air cylinder and so arranged as to deliver a sharp blow to the end of a prescribed brick during the upward portion of its arcuate path. Such an arrangement imparts to the brick a strong, upward and outward movement without further or continuous engagement by the lever, and eliminates the frictional drag of the conveyor belt facilitating removal of the brick therefrom. The transverse path of the lever is angularly adjustable with respect to the conveyor path, so that the force imparted by the lever includes a longitudinal component along the conveyor path as well as a transverse component to utilize somewhat the impetus of the brick along the conveyor in lifting and removing it therefrom.

Claims, 12 Drawing Figures

<img file="US3666093A_D0001.tif" />

Patented May 30, 1972

3,666,093

Sheets-Sheet 1

<img file="US3666093A_D0002.tif" />

FIG. I

<img file="US3666093A_D0003.tif" />

LAVERNE THORNTON

GERALD L. STUART

INVENTOR

BY

Patented May 30, 1972

3,666,093

Sheets-Sheet 2

<img file="US3666093A_D0004.tif" />

Patented May 30, 1972

3,666,093

Sheets-Sheet 3

<img file="US3666093A_D0005.tif" />

FIG. 5

LAVERNE THORNTON

GERALD L. STUART

INVENTOR

BY

Patented May 30, 1972

Sheets-Sheet 4

3,666,093

<img file="US3666093A_D0006.tif" />

<img file="US3666093A_D0007.tif" />

LAVERNE THORNTON

GERALD L.STUART

INVENTOR

BY

Patented May 30, 1972

3,666,093

Sheets-Sheet 5

<img file="US3666093A_D0008.tif" />

<img file="US3666093A_D0009.tif" />

FIG. 8

LAVERNE THORNTON

GERALD L. STUART

INVENTOR

BY

<img file="US3666093A_D0010.tif" />

Patented May 30, 1972

3,666,093

Sheets-Sheet 6

<img file="US3666093A_D0011.tif" />

<img file="US3666093A_D0012.tif" />

<img file="US3666093A_D0013.tif" />

<img file="US3666093A_D0014.tif" />

FIG. 10

LAVERNE THORNTON

GERALD L. STUART

INVENTOR

BY

3,666,093

APPARATUS FOR SENSING AND EJECTING BRICKS OF IMPROPER SIZE

BACKGROUND OF THE INVENTION

There are several brick-making processes in use for forming bricks from clay prior to curing. One such process includes extruding a raw clay column of such transverse dimensions as to form the proper length and width of the bricks, moving the column of clay through a cutter including a series of spaced wire cutting arms on a rotary wheel revolving transversely of the extruded clay column, thus severing the column into a plurality of bricks of the proper thickness. In order to form a transverse cut, the cutter moves along the conveyor during its operation, and at the end of each cut, indexes back to its initial position, preparatory to making a succeeding cut. A waste slab is formed between each cycle having a thickness dimension different from that of the other bricks. As the bricks are cut, they are deposited on an off-bearing conveyor moving slightly faster than the clay column, thus causing a space between the bricks on the conveyor. The extruder is so arranged with respect to the conveyor belt, that the length dimension of each brick lies transverse of the conveyor while the thickness dimension lies longitudinally of the conveyor.

The aforementioned waste slab, as well as other defective bricks of improper sizes which may be formed due to the breakage of a wire in the cutter, must be removed from the conveyor at some point prior to the stacking or hacking of the bricks onto a kiln car for movement to a kiln. It has become conventional practice in the industry to position an operator at this point to manually remove all such waste slugs and improperly sized bricks from the conveyor.

SUMMARY OF THE INVENTION

The present invention, on the other hand, obviates the need for an operator at the conveyor to remove the waste slugs and other improper sizes of bricks. The apparatus according to the present invention operates on the principle of a kickoff lever automatically activated in response to a size sensing device positioned adjacent the conveyor immediately preceding the kickoff lever. The size sensing device utilizes a light source generating an inclined light path extending transversely across the conveyor and interrupted at the other side by a linearly arranged series of photocells. The use of an inclined light path, through which the corners only of the bricks progress, prevents inadvertent tripping of the ejector mechanism due to a brick being non-perpendicularly disposed with respect to the longitudinal dimension of the conveyor. The use of four photocells adapts the mechanism for use with larger “utility” bricks as well as “standard” sizes. A logic circuit electrically connects the photocells with the kickoff lever and activates the lever in response to a preselected pattern of light impingement and interruption upon the photocells.

The kickoff or ejector lever is pivotally mounted about a horizontal axis and adapted to move in an arcuate path transverse to the conveyor. The path is not necessarily perpendicular to the conveyor path, rather may be adjusted slightly to an angular path, thus imparting a force having a component along the conveyor as well as across the conveyor to take advantage of the impetus imparted to the brick by the conveyor and facilitate removal of the brick therefrom. The raw bricks are spaced approximately one inch apart on the conveyor, and therefore the kickoff lever must engage a prescribed brick, kick it from the belt and return to its position before the succeeding brick passes by to avoid inadvertent engagement of the succeeding brick. In this regard, the stroke of the kickoff lever is very short with respect to those heretofore known. Whereas the bricks are generally 8 to 12 inches in length, the stroke length of the kickoff lever is much less, on the order of five inches and in accordance with the present invention is variable in length to adjust the speed of the kickoff arm.

It is therefore an object of the present invention to provide an apparatus for automatically ejecting raw bricks of improper size from a conveyor carrying the raw bricks from the extruder to the hacking device.

It is another object of the present invention to provide an apparatus of the type described which ejects improperly sized bricks from a conveyor by imparting to them a short, sharp blow, the length of which may be varied, rather than pushing them horizontally and continuously from the conveyor belt.

It is still a further object of the present invention to provide an apparatus of the type described wherein the thickness of each brick is measured by a series of linearly disposed photocells including an inclined light path that impinges upon only one comer of the bricks passing thereby to prevent inadvertent errors in determining brick thickness due to skewing of the bricks on the conveyor belt.

Other objects and advantages of the invention will become apparent by reference to the following detailed description and the accompanying drawings illustrating a preferred embodiment of the invention, in which:

FIG. 1 is a partial schematic representation of a portion of a brick handling machine, illustrating the movement of bricks through the sensing means and kickoff device;

FIG. 2 is an enlarged perspective, with parts broken away for the sake of clarity, illustrating the kickoff mechanism;

FIG. 3 is a plan view of the kickoff mechanism illustrated in FIG. 2;

FIG. 4 is a side view of the kickoff mechanism illustrated in FIG. 2;

FIG. 5 is an end view of the kickoff mechanism illustrated in FIG. 2;

FIG. 6 is a sectional view taken substantially along lines 6— 6 in FIG. 1;

FIGS. Ία-c are sectional views, with parts broken away, taken substantially along line 7—7 in FIG. 1 and illustrating the sequential movement of a brick as it is ejected from the conveyor by the ejecting mechanism;

FIG. 8 is an enlarged plan view, with parts broken away, illustrating the adaptability of the kickoff device to be swung throughout an arcuate path;

FIG. 9 is an enlarged plan view of the photocell arrangement adjacent the conveyor; and

FIG. 10 is an electrical schematic illustrating the logic circuit connecting the photocells and kickoff lever.

Turning now to a description of the drawings, and more particularly with reference to FIG. 1, there is schematically illustrated a portion of a brick handling system including an extruder 10 which extrudes a column C of clay from the exit end thereof, the transverse dimensions of the column equalling the length and width of a brick. A conventional brick cutting wheel 14, comprising a series of spaced cutting wires rotatably mounted in the path of the clay column C, severs the column into raw bricks B of proper thickness and deposits them onto an off-bearing conveyor 12.

Each rotation of the cutter 14 forms approximately 21 bricks, however due to the operation of the cutter, which is conventional and thus will not be herein described, it is necessary to allow for a waste slab W between each cut. In systems having an automatic hacker at the far end of conveyor C, it is necessary to remove this waste slab W from conveyor 12 before it arrives at the hacker. Also, if a wire in the cutting wheel 14 should break, a double brick will be formed which will have to be kicked off prior to reaching the hacker.

An apparatus K for sensing and ejecting bricks of an improper size is positioned in the path of conveyor 12 and includes a sensing means 16, 18 for determining whether a brick is of proper size or not, and a kickoff lever 20. The sensing means includes a light source 16 suitably mounted on one side of the conveyor 12 and a photoelectric sensing means 18 mounted in the light path from said light source. As a brick passes through the light path thus formed, the photoelectric means 18 activates a logic circuit (FIG. 10) to determine the thickness of the brick, and if it is of improper size, activates kickoff lever 20 to eject the brick from the conveyor 12 into a scrap container (not shown) or onto a return conveyor 22 which carries the raw oversize brick back to the extruder to be reprocessed. Kickoff lever 20 is operated by an activating means such as air cylinder 24 selectively activated by the sensing means as described hereinabove.

3,666,093

Turning now to FIGS. 2-5, a kickoff lever mounting frame 30 is suitable mounted to the floor or attached to the frame of the off-bearing conveyor 12 in overlying relationship thereto at a point between the cutter 14 and the hacker (not shown). A plurality of upright legs 32 support at the upper ends thereof horizontal sides 34 and ends 35, joined together at the corners thereof and forming an upper, horizontal, rectangular frame overlying conveyor C. The legs 32, ends 35 and sides 34 may be braced as required, however clearance through main frame 30 must be provided for conveyor 12. As best illustrated in FIG. 3, a pair of upper support members 36, 38 extend transversely of the conveyor 12 between opposite side members 34 of frame 30 and include an end plate 37, 39 at each end thereof joining the ends of supports 36, 38. Additionally one of mounting plates 40, 42 is secured to each of opposed side members 34 in overlying relationship with end plates 37, 39. Each of plates 40, 42 include an arcuate slot 44 therein aligned with similar slots in plates 37, 39, through which bolts 41 slidably attach support members 36, 38 for angular adjustment as hereinafter described.

A pair of journals 46, 48 are secured to the upper surfaces of support members 36, 38 respectively and support therebetween a shaft 50 from which is pivotally suspended an elongated kickoff lever 52 having a front side facing and adjacent conveyor C. A bracket 54 having a series of vertically spaced openings 56 therein is secured to the rear side of lever 52. The rear side, as used herein, refers to the side of lever 52 opposite conveyor 12. The lower end of lever 52 includes a bevelled edge 58 tapering rearwardly and upwardly from the lowermost point 60 at the forward edge thereof for reasons to be hereinafter described. A brick engaging lug 61 is secured to the front side of lever 52 at the lower end thereof. The lever 52 is initially positioned at the lowermost point of its arcuate path, so that any movement of the lever will be in an upward direction from the initial position.

A first stop means in the form of plate 43 is secured between support members 36,38 in the path of lever 52 and defines the forward limit of the arcuate path. A second stop means 45 is suspended from support members 36, 38 in the return path of lever 52 and thus defines the rear limit of the return.

The piston 64 of a double acting air cylinder 62 is attached at the free end thereof to bracket 54 by means of a nut and bolt arrangement which extends through one of apertures 56. The base of air cylinder 62 is suitably attached to a lug 39a depending from plate 39, so that as the support is angularly adjusted, the air cylinder is similarly adjusted. By providing several apertures 56 in bracket 54, it is noted that the speed of the lever stroke may be adjusted. For example, if piston 64 is attached to the upper aperture, it is seen that the lever stroke is faster than if attached to the lower aperture.

Arcuate slots 44 permit angular adjustment of the assembly comprising supports 36, 38, air cylinder 62 and lever 52, and thus adapts the kickoff lever to be activated at angles to the conveyor other than the perpendicular, whereby the force imparted to the brick includes a longitudinal component as well as a transverse component. Such an angular relationship takes advantage of the impetus of the brick due to the conveyor movement.

Upon activation of the piston 64 of air cylinder 62, lever 52 is arcuately moved about shaft 50, so that tip 60 and lug 61 are urged in an upward direction against the edge of a brick B on conveyor 12, imparting to the brick a sharp upward and outward impact to help lift it from the conveyor, rather than a horizontal force which would tend to slide it from the conveyor.

It should be recognized that the use of a short stroke, variable in duration, allows the lever to be adjusted according to the conveyor speed and adapted to return to its normal position before the next brick passes, whereas a horizontally moving lever sliding the brick transversely across the conveyor would interfere with the flow of bricks along the conveyor before it could return. The arcuate stroke of lever 52 is only about 5 inches in length, whereas the bricks range in length from 8 (standard) to 12 (utility) inches.

A separate sensor stand 70 includes an upright leg 71 having attached at the upper end thereof a photocell mounting bracket 72 extending laterally therefrom at a position adjacent conveyor C immediately preceding lever 52 with relation to the path of the bricks (FIG. 9). Photocells 73, 74, 76, and 78 are suitably attached along the free edge of bracket 72 in a linear pattern adjacent the side edge of conveyor 12, and are upwardly inclined to receive a light path from an angle of approximately 20°, rather than being mounted to receive a horizontal light path (FIG. 5).

The photocells 73, 74, 76, and 78 are so spaced that an oversize “standard brick will block all three photocells 74, 76 and 78, however a “standard” brick of acceptable thickness will block only two of the photocells. When processing “utility” bricks an oversize slug will block all four photocells 73, 74, 76, and 78, while an undersize waste slug will block only one photocell at any one time. It was found during experimentation with “standard” brick that if only two photocells were used to measure thickness of oversize bricks, it was possible due to close spacing of the bricks on the conveyor for the rear edge of one brick and the leading edge of a second brick to cover both photocells and activate lever 52. Therefore the three photocell arrangement is preferred, because it forecloses such inadvertent tripping of lever 52, yet allowing closer spacing of the bricks on the conveyor.

A light stand 80 is positioned on the opposite side of conveyor 12 from sensor stand 70 and includes an upper horizontal support arm 82 extending therefrom in a direction toward the conveyor. A light source 84, preferably a 150 watt flood lamp, is attached to the free end of horizontal arm 82 and directs a downwardly inclined light path in the direction of photocells 74, 76, and 78.

FIGS. 7a-7c illustrate the path of a stroke of lever 52 against a prescribed brick B being carried along conveyor C. As illustrated in FIG. 7α, the impact lug 53 of lever 52 is normally positioned close to the adjacent edge of the bricks passing by. As lever 52 is activated, lug 53 is brought into engagement with the side of oversize brick B at a point beneath the center of gravity, imparting to the brick an upward and outward impetus, lifting the brick from the surface of conveyor 12 with sufficient impact to flip the brick off the conveyor as illustrated in FIG. 7c. The lever 52 after impact immediately returns to its normal position, so that the next brick will not be hindered in its path along the conveyor.

Turning now to the logic circuit connecting the photocells 73, 74, 76, and 78 and the kickoff mechanism (FIG. 10), leadin lines 100 and 102, leading from a source of power, such as 220 or 440 volts A.C., are connected to a variable step down transformer 104 providing an output of 120 volts A.C. between lines 106 and 108. An on-off switch 110 selectively carries the power to the kickoff control circuit and provides voltage for operating light source 84 through Variac V.

Each size sensing unit includes one of photocells 73, 74, 76, and 78; one of relays R-l, through R-4; and a set of relay contacts 112, 114α, 114*, 116α, 116*, 118α, or 118*. A selector switch 120 adapts the circuit to selectively bypass or include relay contact 112. Relay contact line 122 joins in series relay contacts 112, 114α, 116α, and 118α and is connected in parallel with contact line 124, which joins in series contacts 114*, 116*, and 118*. Lines 122 and 124 are connected in series with a timer T and solenoid valve S which is effective to operate air cylinder 62.

In operation, and when standard bricks are being processed, selector switch 120 in FIG. 10 is thrown to the left, introducing the current from line 106 into contact line 122 and bypassing photocell 73 and relay R-l. On-off switch 110 is closed to complete the circuit and turn the machine on for operation. All relay contacts 112 through 118, as illustrated in FIG. 10, are shown with the light beam complete, that is being received by the photocells 73,74,76 and 78 and not blocked. Therefore, if a “standard” brick of normal size passes the sensing at no time will the brick block all of photocells 74, 76, and 78, so that the contacts of at least one of photocells 74,76

3,666,093 or 78 will remain open indicating light is impinging thereon and interrupting current flow through the logic circuit, not permitting activation of kickoff lever 52.

On the other hand, if an oversize waste slab W comes along the conveyor, all of photocells 74, 76, and 78 will be blocked and their associated relay contacts 114α, 116α, and 118α, will be closed. Therefore, the signal will proceed from line 106 through the selector switch 120 to relay contact 114α. Since the relay contact is closed, the signal will pass through to contact 116α, and since that contact is also closed, on through relay contact 118a into the timer T. After a preselected time interval, the timer will complete its timing interval and energize solenoid S which in turn energizes a control valve to the air cylinder 62 to operate the kickoff lever 52 forward. At the end of the forward stroke the kickoff lever strikes limit switch 126 closing the normally open contact 128 thereof, and energizing the return side of the solenoid. The valve is a double acting, momentary impulse four-way air valve which means that a signal can be applied to the solenoid for a short interval and the valve will shift and stay in that shifted state until a signal is applied to the opposite side of the solenoid.

For “utility” size bricks, the selector switch 120 is placed in the right hand position whereby current from line 106 enters both contact lines 122 and 124. In such a state the photocell 73, relay R-l, and relay contact 112 are now in operation. In the case of an oversize “utility” on the conveyor all four photocells will be blocked. The signal will enter line 122, passing through the normally open, but now-closed relay contact 112 from whence the signal will continue on through contact 114α, 116α, and 118α and into the timer to operate the air valve. This means that all four photocells 73, 74, 76, and 78 must be blocked in order to signal that an oversize “utility” brick is on the belt. The operation of the kick valve and the limit switch are exactly as explained before, and the same time interval is used for all brick sizes. This time interval is set so that the undersize utility brick has sufficient time to move from in front of photocell 76 to a position in front of kickoff lever 52. The larger bricks will be kicked off suitably by the same time interval, even though they are not necessarily centered exactly with respect to lever 52.

For undersize utilities, the circuit is set up so that if only photocell 76 is blocked at any one time, there is an undersize utility brick on the belt. Such a condition will cause the rejection of the brick in the following manner. Relay contacts 114b and 118b are normally closed, so that when a light beam is shining on their respective photocells 74 and 78, the contacts are closed allowing the signal to pass therethrough. If an undersize brick is on the belt, the signal enters the contact line 124, passes through normally closed contact 114ft, because light is shining on its photocell 74, and passes on to relay contact 116ft which is a normally open contact. Since the brick is blocking photocell 76, it will be switched to its opposite or closed condition passing the signal therethrough. The signal continues on through normally closed contact 118ft whose photocell 78 is receiving light thereby keeping the contact closed, and onto the timer causing the air valve to operate.

Although a specific embodiment of the invention is illustrated and described hereinabove, it is apparent that various changes and modifications may be made to the construction and arrangement of parts, which will readily occur to those skilled in the art, however which will not depart from the spirit of the invention as set forth and intended to be within the scope of the following claims.