Precast brick panel and method of manufacture

Abstract

A method for assembling a brick pattern for forming a precast brick panel. The method includes conveying bricks in a row to a spacing station, spacing the bricks apart in a row at the spacing station according to a predetermined row pattern and to a predetermined row length by allowing the spacing between adjacent bricks to vary if required. The method then involves transferring the row of spaced bricks onto a generally planar support surface of a brick pattern assembly station. By this method, a plurality of rows of spaced bricks are assembled adjacent each other on the support surface of the brick pattern assembly station to form a brick pattern.

Claims

1. An installation for assembling a brick pattern for forming a precast brick panel, the installation comprising: a. a conveyor, b. a spacing station, and c. a brick pattern assembly station, the conveyor being operable to convey a row of bricks to the spacing station, and the spacing station being operable to space the bricks apart in a row according to a predetermined row pattern and to a predetermined row length by allowing the spacing between adjacent bricks to vary, the spacing station including a push facility to push the last brick of a row of bricks into the correct position in the row of bricks, the push facility including a rotatable member or finger that has an inactive position in which it is spaced from the path of bricks within the spacing station and an active position in which it is rotated toward and into engagement with the trailing or rear end of the final brick to push the final brick as required, the brick pattern assembly station including a generally planar and horizontal support surface, the installation including facility to transfer the row of spaced bricks onto the generally planar and horizontal support surface of the brick pattern assembly station and the generally planar and horizontal support surface being capable of supporting a plurality of rows of spaced bricks assembled horizontally adjacent each other to form a multiple row brick pattern on the generally planar and horizontal support surface.

2. An installation according to claim 1, the conveyor being operable to convey bricks to the spacing station generally aligned along their longitudinal axis.

3. An installation according to claim 1, including an automated feed facility operable to feed bricks onto the conveyor in an orientation suitable to be spaced by the spacing station.

4. An installation according to claim 3, the orientation being in lengthwise or axial alignment.

5. An installation according to claim 1, including a robotic placement arrangement operable to feed bricks onto the conveyor, the robotic placement arrangement including a robot operable to pick up bricks from a brick supply and to place the bricks on the conveyor.

6. An installation according to claim 1, the spacing station incorporating a sensing arrangement that senses the forward or leading ends or faces of each brick being assembled into a row and which is operable to space the forward ends of adjacent bricks apart a selected amount.

7. An installation according to claim 1, the spacing station being operable to establish the position of the leading end or face of the initial brick and to bring the leading end or face of the next brick to a position spaced from the leading end or face of the initial brick a predetermined amount.

8. An installation according to claim 7, the predetermined amount being the sum of the average length of the bricks forming the row plus an average mortar gap.

9. An installation according to claim 7, the spacing station including a datum point at which the initial brick can be placed or located and from which the subsequent bricks are spaced.

10. An installation according to claim 1, the spacing station including two conveyors comprising a delivery conveyor and a spacing conveyor, wherein the delivery conveyor delivers bricks to the spacing station and the spacing conveyor delivers spaced bricks away from the spacing station.

11. An installation according to claim 10, the spacing conveyor includes an abutment for engagement by an initial brick.

12. An installation according to claim 11, the abutment being a retractable abutment that remains in place only to engage the initial brick and thereafter is retracted so as not to impede subsequent movement of the initial brick and subsequent bricks.

13. An installation according to claim 10, a sensor being operable to sense when the leading end of a next brick reaches the predetermined spacing relative to the initial brick and once the next brick has reached the predetermined spacing, either or both of the delivery and spacing conveyors being operable to shift the initial and next bricks together forward, so that the spacing between them remains as initially set.

14. An installation according to claim 1, the spacing station including a push facility to push the last brick of a row of bricks into the correct position in the row of bricks.

15. A method for assembling a brick pattern for forming a precast brick panel, the method comprising: a. conveying bricks in a row to a spacing station, b. spacing the bricks apart in a row at the spacing station according to a predetermined row pattern and to a predetermined row length by allowing the spacing between adjacent bricks to vary, the bricks being spaced by a push facility that pushes the last brick of a row of bricks into the correct position in the row of bricks, the push facility including a rotatable member or finger that has an inactive position in which it is spaced from the path of bricks within the spacing station and an active position in which it is rotated toward and into engagement with the trailing or rear end of the final brick to push the final brick as required, c. transferring the row of spaced bricks onto a generally planar and horizontal support surface of a brick pattern assembly station, whereby a plurality of rows of spaced bricks are assembled horizontally adjacent each other on the generally planar and horizontal support surface of the brick pattern assembly station to form a multiple row brick pattern on the generally planar and horizontal support surface.

16. A method for forming a precast brick panel, the method comprising: a. assembling a brick pattern by: i. conveying bricks in a row to a spacing station, ii. spacing the bricks apart in a row at the spacing station according to a predetermined row pattern and to a predetermined row length by allowing the spacing between adjacent bricks to vary, the bricks being spaced by a push facility that pushes the last brick of a row of bricks into the correct position in the row of bricks, the push facility including a rotatable member or finger that has an inactive position in which it is spaced from the path of bricks within the spacing station and an active position in which it is rotated toward and into engagement with the trailing or rear end of the final brick to push the final brick as required, iii. transferring the row of spaced bricks onto a generally planar and horizontal support surface of a brick pattern assembly station, iv. assembling a plurality of rows of spaced bricks horizontally adjacent each other on the generally planar and horizontal support surface of the brick pattern assembly station to form a multiple row brick pattern on the generally planar and horizontal support surface, b. embedding the brick pattern in mortar or cement.

17. A method for forming a precast brick panel according to claim 16, including sensing the forward or leading ends or faces of each brick being assembled into a row and shifting each brick forward a predetermined distance relevant to the spacing required between bricks in the row of bricks being assembled and the length of the bricks.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) In order that the invention may be more fully understood, some embodiments will now be described with reference to the figures in which:

(2) FIG. 1 is a layout drawing of an installation for assembling a brick pattern according to one embodiment of the present invention.

(3) FIG. 2 is a sequence of figures which illustrates how bricks that are placed on the supply conveyor are spaced at a spacing station.

(4) FIG. 3 shows an arrangement in which a brick row includes a half size brick.

(5) FIG. 4 shows an arrangement in which an opening is produced in a brick row.

(6) FIG. 5 shows one form of individual brick that can be employed in the present invention.

(7) FIGS. 6a to 6c show further forms of individual bricks that can be employed in the present invention.

DETAILED DESCRIPTION

(8) FIG. 1 is a layout drawing of an installation 10 for assembling a brick pattern according to one embodiment of the present invention for forming a precast brick panel. The installation has several sections at which different procedures take place as will be described hereinafter.

(9) The installation 10 includes an infeed conveyor 11 which is fed by a forklift vehicle 12 with pallets of bricks 13. The pallets 13 can include either full or half bricks or a mixture of both, or indeed any size or form of bricks that are to be used.

(10) A robot 15 is operable to grab and lift full and half bricks from the pallets 13. The robot 15 itself can be of a generally standard form as having six degrees of freedom, and can have a grabbing facility at the free end of the robot 15 that includes a series of individual grippers (these are not readily apparent in FIG. 1 but the grippers of the robot 15 are the same as the grippers 21 of the robot 20 that is described below). In FIG. 1, the grabbing facility includes six grippers, each for gripping a single brick, so that the grabbing facility can grip and lift up to six bricks at a time. Not all grippers need necessarily grip a brick each time the robot 15 takes bricks from the pallets 13 as the robot is programmed to selectively grab bricks so as to present them on an accumulation conveyer 18 for a subsequent selection by a loading robot 20. The robot 15 thus grabs and places full and half bricks on the accumulation conveyor 18 in a manner that facilitates access to full and half size bricks by the loading robot 20.

(11) The loading robot 20 has the same construction as the robot 15, in that it also includes six grippers 21. The loading robot 20 is programmed to grab and lift bricks from the accumulation conveyor 18 for placement on a supply conveyor 24. The loading robot 20 might lift six bricks at one time and all being full size bricks, or it can lift less than six bricks and/or a mixture of full and half size bricks depending on the programme that the robot 20 is operating under.

(12) The grippers 21 of the loading robot 20 are linearly aligned so that where it lifts multiple bricks, the bricks are linearly aligned. This allows the bricks lifted by the loading robot 20 to be laid on the supply conveyor 24 as discussed below.

(13) The supply conveyor 24 can be termed a “linear” conveyor, in that it has a straight lengthwise axis. The supply conveyor 24 also has a width to accommodate the width of a single brick. The supply conveyor 24 is therefore long and thin. Neither being linear or of a width to accommodate the width of a single brick is essential, but is convenient in the installation 10 illustrated. The supply conveyor 24 is intended to provide bricks in a row for appropriate spacing at a spacing station, so that the bricks are spaced apart sufficiently for a mortar or cement solution to flow between them, and also for the entire row to be of a particular length for formation of a precast brick panel. The aim is to produce rows of bricks in which the row length is substantially the same for each row, so that rows of bricks can be formed or placed adjacent each other with opposite ends of adjacent rows being aligned. This consistency of row length has been a particular difficulty in prior art precast brick panels. Where rows of bricks have different lengths, even though the length variation might only be small and say within 5 mm to 15 mm, the aesthetic appearance of the brick panel can be adversely affected.

(14) The supply conveyor 24 conveys bricks that have been loaded onto it by the loading robot 20 to a spacing station 25 that includes a sensor 26. The sensor 26 is positioned towards the end of the supply conveyor 24 and is operable to sense the forward or leading end of each brick that passes by it so that once the position of the forward end is known, the supply conveyor 24 can continue to convey the brick forward past the sensor 26 and onto a setting conveyor 28, which is co-linear with the supply conveyor 24 and which is separated from the end of the supply conveyor 24 by only a very small gap. Once the forward end of the brick reaches the setting conveyor 28, the setting conveyor is also driven to move so that the brick is driven by both conveyors 24 and 28 until the rear end of the brick leaves the supply conveyor 24 and drive of the brick is by the setting conveyor 28 only.

(15) While the operation of the spacing station 25 will be discussed in greater detail in relation to FIG. 2, the installation 10 further includes a brick pattern assembly station which includes a setting robot 30 that can pick and lift a row of bricks that is presented to it on the setting conveyor 28. The setting robot 30 grabs or picks the entire row that is presented to it on the setting conveyor 28 and lifts the row onto a setting table 31. In FIG. 1, three setting tables have fully formed brick patterns shown at pattern numbers 32, 33 and 34. Each of the patterns 32 to 34 has been created by firstly forming separate rows of bricks through the spacing station 25 and delivering the formed rows via the setting conveyor 28 to the setting robot 30. Each row is then lifted from the setting conveyor 28 by the setting robot 30 onto a setting table and rows are added until a full brick pattern has been assembled. The brick pattern is then shifted away from the setting robot 30 as shown in relation to the patterns 32 to 34 and can later be lifted from the setting tables for delivery to a mortar or cement station for immersing the bricks in appropriate mortar or cement and for the application of other fittings relevant to the precast brick panel as required. For this, the brick patterns can be formed on a support surface, which can be a removable planar substrate which sits on the setting table and which can be lifted from the setting table. The support surface can include a rigid substrate such as a metal sheet or panel on which a layer of flexible or malleable material such a rubber or foam is laid. Alternatively, the setting tables themselves can be moved to the mortar station and delivered back once the mortar or cement has been poured and set and the brick panel has been formed.

(16) Reference will now be made to the sequence of figures of FIG. 2 which illustrates how bricks that are placed on the supply conveyor 24 are spaced at the spacing station 25.

(17) FIG. 2 schematically illustrates through a sequence of drawings a to g, a portion of the spacing station 25 that can space bricks in a row to a particular row length. The spacing station 25 of the invention that has been developed provides a high degree of accuracy for row length and advantageously that means that multiple rows of bricks can be formed to almost exactly the same length, which provides a highly aesthetic appearance in precast brick panels formed by the invention. FIG. 2 is not to scale.

(18) The spacing station 25 incorporates a sensing arrangement that senses the forward end of a brick which is conveyed to the spacing station 25. In FIG. 2, the sensing arrangement includes a sensor 40 that is positioned at the leading end of the supply conveyor 24. The supply conveyor 24 is aligned axially with the setting conveyor 28 with a very slight gap between them so that the respective conveyors 24 and 28 can be rotated independently of each other.

(19) The formation of a row of bricks involves delivery of individual bricks along the supply conveyor 24 and past the sensor 40. FIG. 2a shows a first brick 45 being moved along the supply conveyor 24 towards the sensor 40. For the purposes of the following discussion, the brick 45 and each of the other bricks that are shown in FIG. 2 are full size bricks that have a nominal length of 230 mm. As indicated above, the actual size of the brick can vary usually by ±3 mm.

(20) In FIG. 2a, there are no bricks on the setting conveyor 28 at least in the region of the sensor 40. For the first brick 45, the sensor 40 is not required to sense the leading end 46. This is because for the first brick in a row of bricks, the leading end of the brick can be placed or located at a datum point from which the subsequent bricks are spaced. Thus, the first brick 45 can be delivered so that the leading end 46 of the brick engages either of the abutments 47 or 48, depending on whether the brick is a half or full brick. In FIG. 2, the bricks shown are full bricks and so it can be seen from FIG. 2b, that the leading end 46 of the brick 45 has engaged the abutment 48. The abutment 47 has been shifted out of the path of the brick 45 to allow the passage of the brick 45 to the abutment 48. Had the brick 45 been a half brick, the abutment 47 would have remained in place so that the leading end 46 would have engaged the abutment 47.

(21) The abutments 47 and 48 are lowered into position from above prior to the first brick being delivered to the setting conveyor 28. The appropriate abutment is lowered depending on the size of the first brick that is to be delivered to it. This is part of the programming of the loading robot 20 that loads bricks onto the supply conveyor 24. The loading robot 20 is programmed to select the bricks required to form a row and will select full or half size bricks depending on requirements. For example, because adjacent rows of bricks of a brick panel are spaced apart half a brick, one of the adjacent rows necessarily requires a half brick within the row to form a row that has the same length as the adjacent row. The half brick is normally placed at either end of the row, although that is not essential. It follows, that if a row is to commence with a half brick, then the abutment 47 is lowered. Conversely, if a row is to commence with a full brick, then the abutment 48 is lowered.

(22) Once the first brick has engaged the relevant abutment, its place on the setting conveyor 28 is established and the abutment can be raised or removed so that the first brick can be conveyed forward by the setting conveyor 28 as further bricks are introduced. A simple solenoid operation can be used to present and remove the abutments 47 and 48. The abutments 47 and 48 can be raised and lowered or moved laterally (sideways) to the axis of the supply and setting conveyors 24 and 28.

(23) FIG. 2c illustrates the brick 45 in position on the setting conveyor 28 with the leading end 46 thereof at the datum point 50 (the datum point 50 is shown by an imaginary line) with the abutment 48 having been withdrawn. The brick 45 stationary on the setting conveyor 28. FIG. 2c also illustrates a second brick 51 moving towards the sensor 40 on the supply conveyor 24. When the leading end 52 of the brick 51 reaches the sensor 40 as shown in FIG. 2d, the sensor 40 senses the position of the leading end 52. This knowledge of the position of the leading end 52 is combined with the knowledge that the leading end 46 of the brick 45 is at the datum point 50 means that the supply and setting conveyors 24 and 28 can now operate together to shift the leading end 52 of the brick 51 to a position that is 240 mm spaced from the leading end 46 of the brick 45. Regardless of whether the brick 45 is actually 230 mm in length, or say 227 mm or 233 mm in length, the spacing between the respective leading ends will be 240 mm. The gap between the leading end 52 of the brick 51 and the trailing end 53 of the brick 45 will be 10 mm if the brick 45 is actually 230 mm in length, or it will be 13 mm or 7 mm if the brick is respectively 227 mm or 233 mm in length. But this variation in spacing is not of issue to the aesthetic appearance of the precast brick wall formed by the invention, but rather, of importance is that the length of the rows of bricks formed in the brick wall are of the same length and this is achieved as described hereinafter.

(24) FIG. 2e shows the bricks 45 and 51 positioned adjacent each other on the setting conveyor 28. Thus, the brick 51 has been shifted by the supply conveyor 24 to the point at which it bridged the gap between the supply and setting conveyors 24 and 28 and moved onto the setting conveyor 28. The setting conveyor 28 has then commenced movement to shift both of the bricks 45 and 51 together. Thus, the brick 45 has shifted forward or along from its position in which its leading end 46 was at the datum point 50 and the leading end 52 of the brick 51 has shifted towards the datum point 50. FIG. 2e also shows a new brick 55 that was earlier placed on the supply conveyor 24 by the robot 20, moving towards the bricks 45 and 51 on the supply conveyor 24. So in FIG. 2e, both of the supply and setting conveyors 24 and 28 are moving.

(25) FIG. 2f shows the brick 55 reaching the sensor 40, with the leading end 56 of the brick 55 being sensed by the sensor 40. The position of the leading end 56 is thus established and because the position of the leading end 52 of the brick 51 is known, the supply and setting conveyors 24 and 28 can operate together to shift the leading end 56 of the brick 55 to a position that is 240 mm spaced from the leading end 52 of the brick 51.

(26) FIG. 2g shows the bricks 45, 51 and 55 in position on the setting conveyor 28 with the illustrated dimensions showing the 240 mm spacing between the leading ends 46 and 52, and the leading ends 52 and 56. This spacing can be achieved between successive bricks such as the brick 58 moving on the supply conveyor 24 towards the bricks 45, 51 and 55. The result is a row of bricks that have a 240 mm spacing between the leading ends of successive bricks for the length of the row. A row of 10 bricks will therefore have a length of 2390 mm. This is regardless of tolerance differences in the lengths of individual bricks. This contrasts with the normal manner of creating rows of bricks, which is to space the bricks apart 10 mm so that unless variations in brick length cancel themselves out over the full row, one row of bricks will have a different length to the next. In the present invention, consistent row length is established by accommodating the differences in the length of individual bricks in the gaps between adjacent bricks in the row.

(27) The discussion above has been made in respect of the formation of a row of bricks that is uninterrupted and that consists entirely of full size bricks. Advantageously, the present invention can accommodate half size bricks in the row, as well openings in the row that are applied to accommodate in the formed brick panel, windows and doors. The present invention does this by the appropriate movement of the supply and setting conveyors 24 and 28. For example, FIG. 3 shows the three bricks 45, 51 and 55 of FIG. 2g in position, but with a half brick 60 replacing the full size brick 58. The brick 60 is just about at the sensor 40 and once there, the leading end 61 will be sensed and the supply and setting conveyors 24 and 28 will operate in the same manner as described hereinbefore in relation to the full size bricks with the spacing between the respective leading end 61 of the brick 60 and the leading end 56 of the brick 55 still being 240 mm. The spacing would change if the brick 60 was followed by a further brick, whereby the spacing between the leading end 61 of the brick 60 and the leading end of the following or successive brick will be 120 mm due to the half size of the brick 60.

(28) An opening in a row to accommodate windows and doors is illustrated in FIG. 4. In FIG. 4, bricks 65 to 70 are shown, with brick 65 being a half size brick and bricks 66 to 70 being full size bricks. Bricks 67 to 69 have been positioned in the manner shown in FIG. 2g to form three adjacent bricks in which the respective leading ends are spaced 240 mm apart. However, the pattern of the precast brick panel that utilises the row of bricks shown in FIG. 4 includes a window opening G equivalent to the length of three bricks. To create this opening G, the movement of the supply and setting conveyors 24 and 28 is made to shift the bricks 67 to 69 3×240 mm before introducing the brick 66. The leading end 67.sub.1 is therefore shifted 720 mm before the brick 66 is introduced behind it. The leading end 66.sub.1 is therefore 720 mm behind or spaced from the leading end 67.sub.1. Thereafter, the process operates as previously described whereby the leading end 65.sub.1 of the brick 65 is introduced 240 mm behind the leading end 66.sub.1 while the leading end 701 of the brick 70 is introduced 120 mm behind the leading end 65.sub.1 of the brick 65.

(29) The row of bricks of FIG. 4 would be repeated in several rows so that when adjacent rows are formed in a brick pattern, the opening that is formed has both width and depth.

(30) It is to be noted that the illustration of a half size brick 65 is to show that a brick row can include both full and half size bricks and that half size bricks can be introduced at the end or ends of a row, or intermediate the ends. The half size bricks can also be introduced at the edges of openings that are formed in a row.

(31) Returning to FIG. 1, the row of bricks that is formed at the spacing station 25 is conveyed to the setting robot 30 to be picked from the setting conveyor 28 and placed on a setting table 31. The setting patterns 32 to 34 are completed patterns, while the pattern being applied by the setting robot 30 to the setting table 31 is under construction.

(32) A typical row of bricks could be 20 bricks long, while the number of adjacent rows in a brick could be 30 rows deep. As indicated above, once the brick pattern has been formed, it is transported or conveyed to a mortar or cement station for embedding the pattern in cement or mortar to form the precast brick panel.

(33) The spacing station 25 can include a push facility to push the last brick of a row of bricks to take the correct position in the row of bricks so as to correct any final error in the length of the row being formed. Thus, the last brick in a row of bricks need not be accurately placed at first instance but rather, can be positioned adjacent the previous brick and the push facility can operate to push it to the final position in which the overall length of the row of bricks is accurate. The push facility can include a pair of rotatable members or fingers 71 (see FIG. 4) that have an inactive position spaced from the path of bricks within the spacing station 25 and an active position rotated toward and into engagement with the trailing or rear end of the final brick to push the final brick as required (see the movement indicated by the arrows associated with the respective fingers 71). The rotatable fingers 71 of FIG. 4 are separately shown in the active and inactive positions although they will always be in the same position, i.e. active or inactive, so that the different positions shown in FIG. 4 are for illustrative purposes only. Also, the fingers 71 are shown associated with the brick 65, which is not actually the final brick in a row and so again, FIG. 4 illustrates the operation of the fingers 71 but not in respect of a final brick as would be the case in practice. It will be appreciated that the distance the fingers 71 push a brick can be in the order of only several or a few mm and so the distance is not great.

(34) FIG. 5 illustrates a brick 72 for use in the present invention and which is shown upside down and in which a pair of posts 73 that have been embedded in the rear surface of the brick project outwardly from the rear surface and include a flared or widened head 74. These posts 73 assist to fix the brick 72 within the cement or mortar bed within which the bricks are embedded. That is, the flared or widened heads 74 of the posts 73 finds purchase within the cement or mortar bed resisting dislodgement of bricks from the precast brick panel once formed.

(35) Alternatively, FIGS. 6a to 6c illustrates three alternative forms of brick that have been developed and that include interlocking or interengaging projections. The brick 75 of FIG. 6a has a flat front facia 76 that is exposed in the precast brick panel and a rear face 77 that is embedded in cement or mortar of the panel. For purchase within the cement or mortar bed, the brick 75 has a pair of shaped projections 78 that have a narrow neck 79 adjacent the rear face 77 that connects to a wider head 80. As will be readily appreciated, the cement or mortar bed will flow into the neck 79 which will resist dislodgement of the brick 75 from the precast brick panel once formed.

(36) The brick 85 of FIG. 6b is a corner brick and so has a flat front facia 86 and a flat side facia 87 perpendicular to the front facia 86. Both facia are exposed in the precast brick panel. The brick 85 has a shaped projection 88 that extends from the inside corner of the rear face 89 and the projection 88 has a similar or is of substantially the same form as the projections 78 of the brick 75 of FIG. 6a. That is, the projection 88 has a narrow neck 90 that connects or extends to a wider head 91. As with the projections 78, the cement or mortar bed will flow into the neck 90 which will resisting dislodgement of the brick 85 from the precast brick panel once formed.

(37) The brick 95 of FIG. 6c is another corner brick in which the front facia 96 has twice the length of the side facia 97. The brick 95 thus includes a projection 98 that is equivalent to the projections 78 of the brick 75 of FIG. 6a, and a projection 99 that is equivalent to the projection 88 of the brick 85 of FIG. 6b.

(38) The installation illustrated and described in relation to the drawings has been found to form very accurate brick rows for producing very accurate brick patterns for subsequent immersion or embedding in mortar or concrete to form brick panels. The installation is highly automated and manual intervention is limited to the delivery of pallets of bricks to an infeed conveyor, such as by a forklift vehicle. The installation can thus run relatively autonomously without down time. The invention is anticipated to provide a breakthrough in the production of high quality and aesthetically pleasing precast brick panels, which have not been successfully commercialised before.

(39) Where any or all of the terms “comprise”, “comprises”, “comprised” or “comprising” are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components.

(40) Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.