Patent Application
20060216114
The present invention relates generally to an apparatus and method for controlling a concrete screeding assembly during the leveling and smoothing of freshly poured concrete, as well as somewhat partially cured concrete, that has been placed over a surface.
There is a continuous and growing need within industry for flat and level close-tolerance concrete floors used in a variety of structures such as office buildings, shopping centers, warehouses, and production and/or manufacturing facilities. Most modern production and manufacturing plants include high-precision machinery and equipment which must be set level on a flat surface. A main benefit from achieving close-tolerance floors is that it will allow for easier installation and set-up of the precision machinery and equipment. This allows a facility to reach its intended level of performance capacity sooner and at a higher level of quality. Facility maintenance costs are also likely to be reduced. When changes to the machinery become necessary, reorganization and set-up of the equipment can also be less costly.
For example, high-density warehouse facilities often utilize narrow aisles and high-reach forklifts to reach tall storage racks containing shelving or storage racks for material goods. Any offset error variation from the desired and ideally level floor can correspond to a proportionally larger vertical offset error at the raised forks of high-reach forklifts. Large vertical offset errors at the forklift forks result in an increasingly greater difficulty in maneuvering the forklift machines along the aisles and while reaching for materials and goods at the upper most shelves. Therefore, flatness or levelness errors in the concrete floor become a limiting factor in the practical design of high-density vertical-storage warehouse facilities. Thus the benefit of having easy to produce smooth and accurately level floors in a high-rise warehouse increases the investment value and efficiency of the facility according to a cost per square foot or cost per square meter basis. In locations where land or real estate values are high or available space is at a premium, such costs are an important factor.
In another example, production facilities containing lines of high precision machinery that must be both level and accurately set with respect to one another also significantly benefit from concrete floors that have been placed accurately and economically. The effort required to adjust or otherwise place shims under the supports of the machinery can be reduced or made unnecessary providing that the concrete floor is accurately level and smooth from the start. This can significantly reduce the cost of initially setting up a production line or later making changes or upgrades to equipment as may be necessary. Smooth and accurately level floors may also contribute to reducing overall maintenance costs related to the equipment over the life cycle of the production facility.
Close-tolerance concrete floors are generally known in the concrete construction industry as “super-flat floors” or simply “super flats”. Super-flat floors are typically expensive for building owners to buy and concrete contractors to produce, since such projects usually require specialized equipment and experienced personnel with a thorough working knowledge of the process. Because of the relatively higher cost of the super-flat floors, often only specified areas of a building floor will be made to super-flat specifications, such as within anticipated aisleways of a given floor plan. When changes for the floor plan are necessary however, the spacing and location of the aisle ways cannot be easily adjusted or moved. This limitation increases renovation costs and possibly reduces the future investment value and long-term usefulness of the facility.
Close-tolerance, super-flat concrete floors are specified, measured and compared in the concrete industry according to concrete floor profile specification variables. One of these variables is for floor flatness “F-F” and another is for floor levelness “F-L”. These two specifications together are generally referred to in the industry as F-numbers. The F-number system offers a repeatable method for measuring floor quality through statistical means known in the art. Concrete floors having F-numbers near or above the range of F-F 80 and F-L 80 are typically regarded as being super-flat concrete floors.
Super-flat concrete floors are much more difficult and expensive to achieve than those conventionally poured. In order to achieve such super-flat floors, construction work site personnel must be highly trained and skilled, and special equipment is often required to place and finish the concrete. Skilled workers using hand tools can perform the task of striking-off wet, uncured concrete to a specified grade with a conventional floor. However, a large number of workers are required to finish the floor. Production speed of the floor is thus relatively slow with such a conventional process. Additionally, as even the best skilled worker continues to use his tools of the trade, over the course of a day, the worker will fatigue and tire as the day goes on. Human endurance has its typical limitations. This factor can also have an adverse effect on the final F-numbers and quality of the floor. Therefore, because many flat surfaces are finished by manual labor, the surfaces are likely to have relatively poor or inconsistent quality with regard to overall levelness and flatness.
In order to achieve super-flat or otherwise high quality concrete floors, the use of a laser-guided or laser-controlled screeding device, such as the patented LASER SCREED™ screeding machine or device, developed by Somero Enterprises, LLC of Houghton, Mich., may be used to initially level and screed the freshly poured concrete. Other devices or machines for smoothing and screeding uncured concrete that use similar structural elements could be used also. The Somero LASER SCREED™ machine or apparatus and method is described in detail in U.S. Pat. Nos. 4,655,633 and 4,930,935, both entitled SCREEDING APPARATUS AND METHOD, which are hereby incorporated herein by reference. Additionally, U.S. Pat. No. 6,227,761, entitled APPARATUS AND METHOD FOR THREE-DIMENSIONAL CONTOURING, which is hereby incorporated herein by reference, discloses a contouring device and apparatus for producing contoured concrete surfaces over non-flat areas. These would be concrete surfaces such as, for example, those found with driveways, parking lots, paved roads, walkways, and other similar non-planar areas. A detailed review of these inventions will not be included herein but may serve as references as to their specific limitations and help to gain an understanding of the benefits of the invention disclosed herein. For the purposes of illustration and disclosure of the invention herein, a Somero LASER SCREED™ screeding machine will be used as the example.
The typical Somero LASER SCREED™ screeding machine used to produce super flat concrete floors is comprised of essentially the same or similar mechanical elements as that of a standard screeding machine. These elements may include a base machine having a power source supporting a rotatable telescopic boom. The telescopic boom supports a screeding assembly or screed head typically consisting of three elements, a plow, rotating auger, and a vibrating member. The support boom is extended outward over the freshly poured concrete and the screed head is then lowered to the desired grade elevation. The laser control system takes over from this point and the boom is steadily retracted to engage and smooth the concrete. As the boom is retracted, the screed head is continuously controlled by the laser-controlled hydraulic system according to a laser reference plane. This produces a generally level and smoothed concrete surface at the desired elevation. When the boom reaches its retracted position, the screed head is raised out of the concrete. The entire machine is then moved laterally to the next adjacent position and the boom is again extended for another smoothing pass. The screed head is then once again lowered into the concrete where the process is repeated until all the concrete has been leveled and smoothed.
It is important to note that the plow, auger, and vibrator that are on the Somero LASER SCREED™ screeding machine are pivotable about a horizontal axis perpendicular to the direction of travel over the concrete, wherein the pivoting motion is controlled by a set of actuators, such as hydraulic cylinders or the like, via a control system. The control system maintains the proper relative orientation of the screed head components relative to the desired concrete surface throughout any variations of concrete forces against the plow, auger, and vibrator, as well as any horizontal inclination or deflection of the telescopic boom or support structure of the machine. This unique capability is disclosed in detail in U.S. Pat. No. 4,930,935, issued to Quenzi et al., and referred to in U.S. Pat. No. 6,227,761, issued to Kieranen et al., both of which are hereby incorporated herein by reference.
An interesting and significant aspect of existing screed head designs is that the vibrating member is typically set at an elevation that is just slightly below the desired finished surface elevation of the concrete during normal screeding operations. In other words, while the rotating auger cuts, fills, and establishes the concrete at the desired grade, the vibrating member that follows is set slightly below grade. Accordingly, as the concrete is freshly leveled by the auger and the surface is subjected to the final action of the vibrating member, the concrete is essentially pressed downward by the working face of the vibrating member. Due to the resiliency of the freshly poured and smoothed concrete, the vibrated material almost immediately and effectively “springs back” or flows upward, returning to the desired elevation set by the auger. This action is continuous along the full length of the vibrating member. The concrete returns to the desired grade in the wake of the action of the vibrating member as it passes over the concrete. This is a proven characteristic in concrete having typical construction slump consistencies and characteristics. Typically, the trailing edge of the vibrating member is adjusted or set to about ⅛th to ¼th of an inch (about 3 mm to 6 mm) below the desired level of the smoothed concrete.
There exist, however, limitations toward achieving super-flat high quality floors that are a result of the above-described physical aspect. When the screed head is lowered down onto the concrete at the beginning of a smoothing pass, it is typically overlapped onto the previously smoothed concrete of the adjacent and/or previous set of passes. Because the vibrator is set at a height just slightly lower than desired grade, the vibrator creates a depression in the concrete surface roughly equivalent to the length and width of the vibrating member. With typical concrete floors having non-critical F-number specifications, the landing depressions created by the vibrating member can be simply disregarded in the process. On the other hand, the landing depressions can be typically reduced or possibly eliminated through manual secondary operations using hand tools such as by use of a “highway straight edge” or “bump cutter” tools. However, access to the concrete surface can be a limitation. Workers using these tools may be greatly limited during “wide placement” site conditions or high rates of production. Final concrete trowling and finishing operations can also help to “hide” the landing depressions. However, the actual accuracy of the finished concrete floor surface is likely to remain in question. With super-flat concrete floors, however, the created landing depressions become an even greater limitation toward achieving high-quality floors having high F-number characteristics.
The degree of the created “landing depression” is often dependent on a number of factors. An experienced screeding machine operator can reduce the creation of landing depressions by the carefully coordinated practice of lowering the screed head into the concrete while beginning retraction of the boom. The vibrator may be turned off temporarily, and then quickly turned back on again just at the correct moment in time during the landing. This coordinated technique is known by some experienced screeding machine operators as a “soft landing”. However, such soft landings can be difficult to achieve on a consistent or repeatable basis, and are largely dependent on the level of skill and experience of the screeding machine operator. In addition, the slump condition, degree of cure, and other physical characteristics of the uncured concrete can play a large role in the results.
A further factor beyond that of the control and experience of the operator becomes apparent when soft landings are made on concrete that has already begun to set-up or cure. Concrete that has been leveled and smoothed and then left undisturbed for a period of time will progressively begin to loose its resiliency or ability to flow. The length of time is not easily determined and is subject to many variables such as the prevailing conditions that exist at the site or the mix design of the concrete. Warm, dry and windy conditions may cause the concrete to quickly dry and harden at the surface, while cool and damp conditions may have the opposite effect. Concrete mix designs may also exhibit varying degrees of allowable working time before the resiliency or workability of the material is lost. For example, low slump concrete is by definition stiff and less resilient than high slump concrete, while high-slump concrete flows more readily and smoothly than low-slump concrete and is more easily worked. Also, low slump concrete may be more difficult to work, but often offers higher cure strength by containing less water in the mixing ratio. These variables are important factors with respect to the soft landing of the vibrating member of a LASER SCREED™ screeding machine or other screeding machine when producing high-quality super-flat floors.
A typical wide-placement concrete pour, for example, might consist of a set of eight to sixteen screeding passes from left to right before another row is started. This number of consecutive passes would normally complete the full width of a wide-placement concrete pour. By the time the screeding device returns to the beginning of the next series of smoothing passes, the earlier smoothed concrete may have already begun to set-up. In this case, the screed head must overlap onto the earlier smoothed concrete to produce a substantially continuous and uniform surface. This is where soft landings with the screed head become highly important and valuable. For best results, the vibrating element should not be permitted to substantially or fully engage the already setting concrete within the overlap area of the smoothing pass. If contact between the vibrator and the earlier smoothed concrete is made and sustained, there exists a high likelihood that a landing depression or other irregularity will be created in the previously smoothed and already setting concrete. As the screed head continues onto the freshly poured concrete section, the action of the vibrating member may then again be correct under normal conditions. The area of transition between freshly placed concrete and concrete that has already been screeded and begun to set-up is known in the industry as a “cold joint”. Cold joints are usually minimized as much as possible, however the complete elimination of overlap areas is not reasonably practical. Overlapping the screed head onto previously screeded areas is an inherently necessary and accepted part of the process.
Therefore, there is a need in the art for a concrete smoothing and leveling apparatus that is capable of repeatedly and consistently finishing a concrete surface to a close-tolerance or super-flat level of quality. The apparatus should also help to reduce or substantially eliminate manual labor processes and their inherent variations, and should provide less expensive and higher quality concrete floors and surfaces.
The present invention provides an automatic control system and apparatus for sensing the presence and/or condition of the concrete and temporarily tilting or rotating the screed head assembly of a LASER SCREED™ screeding machine or such similar concrete screeding machines. Alternate to tilting or rotating an entire multi-element screed head assembly, the vibrator alone may be temporarily raised by mechanical means just slightly above the desired grade of the concrete. Accordingly, landing depressions are substantially reduced or eliminated on the concrete surface by the vibrating member as a result of touchdowns or landings of the screed head assembly within overlap areas that have been previously screeded and smoothed.
More specifically, the present invention provides an apparatus and method that improves the control of a concrete screeding assembly during the process of “landing” at the beginning of each screeding pass. Through the use of sensors, mechanical actuators, and an automated controller, and including methods of positioning the vibrating member relative to a screed head assembly in overlap areas, the automated control system of the present invention provides a significant improvement in the surface quality of a concrete floor. The present invention provides a means of sensing the firmness characteristics of the concrete and includes a control system for automatically minimizing the creation of vibrator landing depressions made in the overlap areas of previously screeded concrete. The apparatus and method of the present invention may be generally referred to as a “soft landing” control system for concrete screeding machines.
The present invention provides an automated apparatus and means of preventing the vibrating member from substantially engaging the already set-up concrete a second time in overlap areas. A solution to help solve this problem is to temporarily and independently raise the vibrator relative to the plow and auger. Raising the vibrator up about one quarter inch (6 mm), for example, from the concrete whenever the vibrator is likely to engage previously screeded concrete prevents a second vibration of the material. This is useful where concrete that is beginning to set-up it is not likely to rebound after a second engagement by the vibrator.
The present invention provides an apparatus and method to avoid and minimize the creation of vibrating member depressions in a concrete surface where the screed head re-engages previously screeded concrete material. It also provides a control means for automated and controlled descent of the screed head for re-engagement with the concrete. The apparatus and method of the present invention thus improves the finished surface quality of a screeded concrete surface.
The present invention provides an automatic control system and apparatus for sensing the presence and/or condition of the concrete and providing a signal indicative of such presence and/or condition as an input to a controller. The controller then provides an output signal to automatically achieve a desired adjustment of the concrete screeding head. This includes temporarily tilting or rotating the screed head assembly of a concrete screeding apparatus to raise the vibrating member to reduce or eliminate its engagement with the concrete, or lifting the vibrating member independently with respect to the plow and auger means. Any depressions typically created in the concrete surface by the vibrating member within overlap areas thus become substantially reduced or eliminated.
The screeding device of the present invention thus may include an electronic control feature which may improve the quality and smoothness of the screeded concrete surface by temporarily tilting the screed head, or auger support beam and vibrator, auger and plow, toward the operator as the screed head assembly is lowered onto the uncured concrete or other material surface. The tilting action allows the vibrating device to not penetrate its normal distance (such as approximately 0.25 inches) into the uncured concrete as it is lowered onto the uncured concrete surface. Such an action may be especially useful in landing locations where the uncured concrete has already begun to set up somewhat and has lost its ability to spring back up to the desired grade after the vibrating member has passed over the partially set up concrete material. The soft landing function is intended to improve floor quality F-numbers.
Optionally, the screed head control system may be based on a more detailed software control of the screed head self-leveling system, discussed above. An operator controlled switch on one of the controls of the wheeled base unit of the screeding machine may allow for various mode settings, such as “manual override control”, “auto sensor control”, “delayed head pivoting based on the travel distance of the telescoping boom” or the like. It is further envisioned that the screed head assembly may include an additional actuator or actuators, such as hydraulic cylinders or the like, operable to raise the vibrating device separately and independently, rather than pivoting the entire auger support beam and screed head.
Optionally, additional sensors (not shown) may be included on the screeding device to measure the elevation or travel of the screed head assembly. The sensing signal may indicate the screed head position as it nears the concrete surface, and may be provided by the pair of mast mounted laser receivers mounted at upper ends of the elevation cylinders of the screed head assembly. The controls of the screeding device may initiate rotation of the screed head for raising of the vibrating device just prior to touchdown or contact of the screed head assembly to the uncured concrete in response to the sensing signal provided by the laser receivers.
Optionally, the screeding device may be operable to vibrate the vibrating member only when the screed head is being moved in the screeding direction along and over the concrete surface. If movement of the screed head is stopped, the vibrating motor or vibrating device of the vibrating member may be automatically deactivated, in order to limit or substantially preclude any depressions from occurring in the concrete surface in areas where the screed head and vibrating member may engage or rest against the concrete surface while the screed head is vibrating. When movement of the screed head commences in the screeding direction, the vibrating motor may again be activated to continue to vibrate and screed the concrete surface. Optionally, the vibrating motor may be ramped up to its operational vibration frequency as the vibrating member begins to move along the concrete surface, in order to delay the vibrator motor from reaching its full vibration speed or frequency too quickly before the vibrating member moves along the concrete surface.
Therefore, the present invention provides a concrete smoothing and leveling apparatus that has improved automatic control and is capable of finishing a concrete surface to a close-tolerance or super-flat level of quality. The apparatus and method of the present invention provides an increase in productivity while also providing improved ease of control for the machine operator. The present invention also reduces or substantially eliminates manual labor processes and their inherent variations, and may be relatively inexpensive to implement and operate over a given large-scale concrete leveling project. The present invention also contributes toward less expensive and higher quality concrete floors and surfaces.
These and other objects, advantages, purposes, and features of the present invention will become apparent upon review of the following specification in conjunction with the drawings.
FIGS. 6D-I represent various designs of the concrete sensor wheels that may be interchangeably used with the control system of
FIGS. 7D-G are representations of the relative levels of vibration measured or sensed by the vibration sensor shown in FIGS. 7A-C;
Referring now specifically to the drawings and the illustrative embodiments depicted therein, an automated soft landing control system 10 for a concrete screeding machine or device 12 is automatically operable to control the landing of the screed head assembly 14 onto a concrete surface (
Concrete screeding machine 12 may comprise any type of concrete screeding device or machine, such as a LASER SCREED™ screeding machine as commercially available from Somero Enterprises, LLC of Houghton, Mich., or other types of suitable concrete screeding devices or machines, without affecting the scope of the present invention. For example, screeding machine 12 may comprise a screeding machine of the types disclosed in U.S. Pat. Nos. 4,655,633; 4,930,935; and 6,227,761, which are hereby incorporated herein by reference. In the illustrated embodiment, screeding machine 12 includes a wheeled base unit 16 and an extendable boom 18 with screed head assembly 14 attached thereto. Extendable boom 18 is extendable and retractable to move screed head assembly over and along a targeted concrete surface, while screed head assembly 14 is vertically adjustable relative to boom 18 and rotatably or pivotally adjustable about a generally horizontal pivot axis 36a, as discussed below.
As shown in
The screed head assembly leveling or tilt control system 32 (such as a system of the type disclosed by U.S. Pat. No. 4,930,935, issued to Quenzi et al. and entitled SCREEDING APPARATUS AND METHOD, which is hereby incorporated herein by reference) comprises mechanical, hydraulic, and electrical components for controlling and adjusting the angle of the plow and vibrating member. The embodiment shown in
The actuators 26 and 42 may be hydraulic cylinders that are operable to extend and retract in response to pressurized hydraulic fluid. The screeding machine 10 may include a hydraulic system 43, which may include a fluid reservoir 43a and an engine or motor 43b, which powers a hydraulic pump 43c to provide pressurized fluid to the hydraulic cylinders (and any hydraulic motors of the screeding machine) via the respective control valves. However, although shown and described as having a hydraulic system for extending and retracting hydraulic cylinders, other driving means or power source may be implemented to control or adjust other actuators or the like, without affecting the scope of the present invention.
When leveling and smoothing uncured concrete with the concrete screeding machine or finishing apparatus 12, the operator must overlap the screed head assembly 14 from one smoothing pass to the next. This technique is typically necessary to obtain a continuous and uniformly level and smooth concrete surface over the entire given area as desired. This is shown by the example illustrated in
However, conditions can be quite different at the overlap areas 46 between screeding passes 1-5; 2-6; 3-7; and 4-8. When the entire first row of screeding passes is completed (e.g. passes 1 through 4 in
By design, the position of the vibrating member on the screed head assembly is such that the bottom surface that engages the concrete is set to a slightly angled and fixed position relative to the concrete surface. The leading edge is set just above the surface of the concrete, while the trailing edge just below the desired elevation of the finished concrete. Research and practical experience has determined that the trailing edge should typically be approximately one quarter of an inch (about 6 mm) below the desired elevation of the finished concrete to deliver best results under most conditions. Typically, the screed head assembly is positioned (such as in response to a laser leveling system) such that the auger is positioned to cut or establish the concrete surface at the desired grade, while the plow is positioned slightly above the desired grade so as to allow excess concrete to pass under the plow to the auger.
Accordingly, where the concrete has been previously screeded, such as with passes 1 through 4 in
Additionally, during the process of screeding, when the screed head is extended out over the concrete and then controllably set back down, the “landing” of the screed head, and in particular the vibrating member, may tend to disturb the previously screeded concrete surface. This effect is particularly noticeable when the operator has not correctly anticipated or timed the engagement of the screed head with the location of the transition between the screeded and non-screeded concrete. Smooth vertical downward movement of the screed head via the laser control system in addition to careful operator input to initiate smooth forward movement of the screed head has heretofore been necessary to reduce the effect of “poor landings”.
Therefore, two types of events may cause problems for the finished surface elevation of the screeded concrete. The troughs or depressions caused by the vibrating member at the overlap areas of a series of passes, and the “poor landing” impressions created by the vibrating member as the screed head touches down onto the surface to begin another pass. Both events can tend to diminish the flatness quality or F-F number value of the concrete surface either independently or together.
When operating a concrete screeding machine it can be quite difficult to simply overcome the overlap problem by setting the screed head down (i.e. soft land the screed head) at the exact edge where the previous screeding pass ended. This is largely due to the physical structure and dimensional limitations of the screed head itself. By inherent design, and according to the direction of travel, the auger is set at a fixed distance ahead of the vibrator, and in turn, the plow is set at a fixed distance just ahead of the auger. The fixed spacing of the plow, auger and vibrating member can be reduced to a minimum through improved compact design. However, these relative dimensions are not likely to be eliminated entirely.
When attempting to match the start and stops of each screeding pass at the vibrator, some non-vibrated concrete may be left to remain just behind the auger. Similarly, some non-augured concrete may be left to remain just behind the plow. Therefore, it is impractical and very difficult for the operator to simply match the landing point of the vibrator to the exact point where the previous pass ended. This type of mismatch would typically contribute to produce an uneven and, therefore, poor-quality concrete surface. This type of mismatching is best avoided by ensuring that sufficient overlap is provided in the start and stop points of each screeding pass.
The soft landing control system of the present invention is operable to control the substantial or full engagement of the vibrator or vibrating member with the concrete surface such that such substantial engagement occurs in a smooth and controlled manner and generally at a location where the vibrator is positioned over the uncured and not previously screeded concrete 45 at or near the previously screeded or overlap area 46. The screed head assembly may be lowered toward the concrete surface with the vibrator or vibrating member raised relative to the grade setting device or auger, such that the vibrator does not substantially or fully engage the concrete surface when the auger is positioned on the concrete surface at the desired grade. The soft landing control system may lower the vibrator into substantial engagement with the concrete surface after the auger is set to the desired grade, such as in response to or following an activating event, such as a user input, a detection of the soft concrete at or near the vibrator, a detection of the screed head assembly being at a predetermined height above the desired grade and/or the like, as discussed below. Optionally, the soft landing control system may lower the vibrator into substantial engagement with the concrete surface after a period of time has elapsed following an activating event, in order to provide sufficient time for the screed head assembly and the vibrator to move over and along the concrete surface such that the vibrator will be positioned over the unscreeded concrete and generally next to or at the junction of the unscreeded concrete and the overlap area of previously screeded and partially cured concrete, as also discussed below.
Referring now to FIGS. 4A-C, soft landing control system 10 is operable to automatically control the lowering of the screed head assembly and engagement of the vibrating member with the concrete surface, particularly in the regions of overlap 46, in order to substantially reduce or minimize or eliminate troughs or depressions or other surface irregularities caused by poor landings or overlapping of the screed head assembly. Soft landing control system 10 may be added to and incorporated into the screeding device 12 and screed head assembly 14 of
As shown in
When it is desired to start a new pass adjacent to an end of an already screeded area, screed head assembly 14′ may be lowered down onto the concrete at the overlap area 46 where some of the concrete has already been screeded via an earlier pass of the screed head assembly 14′ (as shown in
With reference to
After the delay period, the delay timer 58 resets to open the circuit to the secondary relay 56 and 4-way hydraulic valve 60. The 4-way hydraulic valve 60 and the small hydraulic cylinder 62 thus return to their initial or normal positions, thereby returning the level sensor 34 to its normal position, such that tilt control system 32 may pivot or adjust screed head assembly 14 and vibrating member 24 to their normal operating positions, with vibrating member 24 being lowered to substantially engage the concrete surface as shown in
As shown in
With reference to FIGS. 5A-C, another soft landing control system 10′ of the present invention is shown incorporated into screed head assembly 14′. Soft landing control system 10′ is substantially similar to soft landing control system 10, discussed above, except that an electric linear actuator 62′ replaces the small hydraulic cylinder 62 of soft landing control system 10. Likewise, secondary relay 56 and control valve 60 are replaced by a secondary relay 56′ and electric switch 60′, which function to actuate linear actuator 62′ in a similar manner as described above. As shown in
As the screed head assembly moves forward (to the left in FIGS. 5A-C), the wobble switch 50 again engages fresh concrete passing under the plow 20 and the contacts 52 of the wobble switch 50 close and thus energize the delay timer 58. After the delay period as set by the delay timer, the switch 60′ retracts actuator 62′ and tilt control system 32 rotates the screed head assembly and vibrating member (such as in the clockwise direction in
Referring now to FIGS. 6A-C, another soft landing control system 10″ of the present invention is shown incorporated into screed head assembly 14′. Soft landing control system 10″ is substantially similar to soft landing control system 10′, discussed above, except that a concrete sensing wheel 50′ replaces the wobble switch 50 of soft landing control system 10′. Concrete sensing wheel 50′ is vertically movable relative to the frame 36′ of screed head assembly, whereby movement of the wheel relative to the frame 36′ actuates a wheel switch 52′. The wheel 50′ either rolls upon the surface of the concrete (such as on the surface of the already screeded overlap area 46 as shown in
As shown in
As the screed head assembly 14′ moves forward, the sensing wheel 50′ may move onto and sink into the freshly placed, less firm, soft concrete area 45, thereby opening the contacts within the wheel switch 52′ and thus opening the contacts of the primary relay 54. The delay timer 58 then maintains power to the secondary relay 56′ and linear actuator 60′ for a short period of time (as set or selected as discussed above) to temporarily avoid actuation of linear actuator 62′. After the time period has elapsed, the linear actuator 62′ may be retracted via switch 60′, such that level sensor 34 pivots in the direction of the arrow A in
Concrete sensing wheel 50′ may comprise a circular wheel or disc of any form, without affecting the scope of the present invention. For example, and with reference to FIGS. 6D-I, various designs of concrete sensor wheels may be selected or interchangeably used with the screed head assembly shown in
Referring now to FIGS. 7A-C, another soft landing control system 110 is shown incorporated into screed head assembly 14′. Soft landing control system 110 includes a vibration sensor or accelerometer 150 that is located adjacent to the vibrator or vibrating member 24 and is able to detect either soft or somewhat firm concrete under the vibrating member via measurement of the level of vibration transferred within the concrete between the vibrating member 24 and the vibration sensor 150. Soft landing system 110 includes a controller 158 that receives a signal from the vibration sensor 150 and that controls a relay 156 and switch 160 in response to the signal. The switch 160 then may extend or retract the linear actuator 162 in response to relay 156, such as in a similar manner as described above.
As shown in
The controller receives the signal from the vibrating sensor 150 and energizes the linear actuator relay 156 to connect or close switch 160 to extend linear actuator 162 in response to a detection of firm concrete that is indicative of the previously screeded and partially cured area 46. With the linear actuator 162 extended, the level sensor 34 is set to its bias position, such that tilt control system 32 pivots screed head assembly 14′ and maintains the screed head in the counterclockwise rotated position shown in
As the screed head assembly 14′ continues to move forward (or to the left in
Optionally, controller 158 may include a timing device or mechanism (not shown) and thus may delay the rotation of the screed head (in the clockwise direction in FIGS. 7A-C) after detection of the softer concrete, such that the vibrating member 24 will not be moved or lowered into substantial engagement with the concrete surface until after it has moved further over and along the surface to be generally at the softer concrete area. Clockwise rotation of the screed head and substantial engagement of the vibrating member with the concrete surface thus may be adjustably timed by the controller to occur smoothly near the transition from the previously screeded and somewhat firm concrete 46 to the soft unscreeded concrete 45 as the screed head continues steady forward movement.
As shown in FIGS. 7D-G, different levels of vibration may be measured or sensed by the vibration sensor or accelerometer. FIGS. 7D-G are exemplary representations of the relative levels of vibration measured or sensed by the vibration sensor or accelerometer of soft landing control system 110. For example,
Referring now to
As shown in
As shown in
Referring now to
As shown in
As shown in
The “level sensor bias position” electrical signal is thus provided internally within the controller of soft landing control system 310. More particularly, programmable computer software within the controller may be implemented to determine the sensor bias position signals based on the sensed input signal of the vibration sensor 350. Thus, the screed head assembly may be rotated (such as in the counterclockwise direction in
Referring now to FIGS. 10A-D, a soft landing control system 410 is incorporated into the tilt control system 32′ and an elevation control system 470, which is operable to control the elevation of the screed head assembly 14. Elevation control system 470 includes a controller 472 that receives a signal from laser receivers 28 (in response to the laser receivers receiving the laser reference plane 29 generated by a remote laser plane generator) and extends or retracts the actuators 26 via a hydraulic control valve 474 or the like, in order to adjust the elevation of the screed head assembly 14 to position the auger or grade setting device 22 at the desired grade. Controller 438 of soft landing control system 410 also receives an input signal from controller 472 or from laser receiver 28 that is indicative of the elevation of the screed head assembly or auger relative to the desired grade.
Controller 438 is operable to rotate the screed head assembly 14 (such as in the clockwise direction in
As shown in
The controller receives and identifies and responds to the input signal when the laser receiver 28 is at a preset or predetermined distance above the on-grade laser reference plane 29 (and thus when the grade setting device or auger 22 is at the predetermined distance above the desired grade). For example, the laser receiver 28 may detect the reference plane at a lower portion of the receiver (as shown in
The rotation of the screed head assembly and lowering of the vibrating member may be delayed by an adjustable or programmable timer within the controller, in order to delay lowering of the vibrating member until the screed head assembly has moved a sufficient distance or amount along the concrete surface. Soft landing control system 410 thus may delay rotation of the screed head assembly to prevent vibrator 24 from engaging the concrete surface where the screed head assembly is initially lowered. As shown in
Referring now to FIGS. 11A-D, another soft landing control system 410′ of the present invention includes a single controller 438′ that is operable to control the soft landing control system 410′, the tilt control system 32′ and the elevation control system 470′ of the screed head assembly 14 and screeding machine. Soft landing control system 410′ may be substantially similar to soft landing control system 410 discussed above, except the separate controllers 438 and 472 are combined into a single controller 438′ in control system 410′. Also, the vibrating member 24′ is attached to the screed head assembly 14 by means of generally vertical low-friction slide bearings 425 or the like. The vibrating member 24′ thus may be independently raised and lowered relative to the frame 36 of the screed head assembly 14 by a pair of electric linear actuators 462 at each end of the vibrator or vibrating member 24′. This eliminates the need to tilt or rotate the entire screed head assembly as shown in the other soft landing control system embodiments discussed above.
As shown in
As shown in
As shown in
Referring now to
When the input or switch 564 is actuated, controller 558 causes rotation (such as in the counterclockwise direction in
As shown in
As discussed above, activation of the soft landing control system 510 occurs when the momentary push button switch 564 is depressed or actuated. Relay 556 is then energized to interrupt or disable the normal self leveling or lowering signal to the hydraulic valve 40′, while relay 554 is energized to enable or activate the raise signal to the hydraulic valve 40′ for a period of time controlled by the one-shot delay timer 558a. The length of the delay determines the height and/or period of time that the vibrating member is temporarily raised from the concrete surface. The delay period is selected to provide sufficient time for the screed head assembly to be moved over and along the concrete surface a sufficient distance such that the vibrator is located over the uncured and not-screeded area of the concrete, such as discussed above.
Optionally, and as can be seen with reference to
Referring now to
If the timed raise button 682 is not depressed at the start of the pass, the self leveling system operates in a normal manner at 742 and no soft landing offset angle is applied to the screed head assembly or vibrator. The screed head elevation may then be controlled by the laser leveling system as it remains generally on grade. Also, if the timed raise button 682 is depressed, but the timed lower button 684 is not depressed, the screed head assembly may remain in its raised position above the concrete at 743 while the soft landing offset angle is applied (or while the vibrator remains lifted). The screed head remains lifted above the concrete and its elevation remains not controlled by the laser system.
Optionally, an override button 664 (
As can be seen in
Optionally, the control may further comprise a vibration control, and may function to automatically deactivate the vibrator motor of the vibrating member when the screed head assembly is not being moved over and along the concrete surface in the screeding direction (i.e., the direction toward the screeding machine, such as to the left in
Optionally, the control may be operable to provide a “soft start” or to “ramp up” the frequency of the vibrator motor when movement in the screeding direction commences. For example, the control may initially activate the vibrator motor at a low frequency when movement is first detected or indicated, and may slowly and/or steadily increase the vibration frequency to the operational frequency (which is higher than the initial low frequency) as the screed head assembly is moved over and along the concrete surface in the screeding direction. The vibrator soft-start control thus may allow the screed head assembly to move a short distance in the screeding direction before the vibrating member comes up to full speed. This soft start feature serves to lessen the impact of the vibrator motor starting too suddenly and forcefully while the vibrating member remains stationary upon the uncured concrete.
Optionally, the soft start function may comprise a hydraulic flow ramp-up feature that may be added to the vibrator control system of the screeding machine. For example, the vibrator control system may consist of a small hydraulic accumulator connected to the input port of a hydraulically driven vibrator motor. The hydraulic accumulator may be charged with a pressurized gas, such as nitrogen gas or the like at a pressure of approximately 200 p.s.i. (although other gasses and/or pressures may be implemented without affecting the scope of the present invention). A floating piston may separate the nitrogen gas from the hydraulic fluid. When at rest, the floating piston is forced toward the single inlet port of the accumulator, whereby all the hydraulic oil is forced out of the accumulator housing. When the vibrator function is first engaged (i.e., when the vibrator motor is activated in response to movement of the screed head assembly in the screeding direction), the pressurized hydraulic fluid that would normally start the vibrator motor turning is momentarily diverted into the accumulator. The fluid is initially diverted because pressurized hydraulic fluid always seeks the path of least resistance, and the starting pressure for the motor is at least slightly higher than the nitrogen pressure behind the piston of accumulator. The pressurized fluid thus initially flows into the accumulator, but as the pressure increases, the hydraulic fluid also enters the vibrator motor and begins gradually rotating the motor to cause the vibration of the vibrating member. As the pressure continues to increase, more fluid enters the vibrator motor to increase the motor speed until the vibrator motor is operating at its full speed or operational speed. The control thus may automatically delay the vibrator motor from reaching full speed too quickly and effectively prolongs spin-up of the motor to full speed.
Optionally, an operator of the screeding machine may select the vibration control function at the controls of the screeding machine. For example, an operator may select an “on” or “auto” or “off” control setting at a vibrator master switch of the screeding machine. The vibrator master switch may comprise a rocker type electrical switch that controls the on-off operation of the screed head vibrator. When the off position is selected, the hydraulically driven vibrator motor (or other type of vibrator motor or vibrating device) is disabled and will not operate. When the auto position is selected, the vibrator motor may only operate while the screed head assembly is being moved or driven in the screeding direction over and along the concrete surface. If movement of the screed head assembly is momentarily stopped while screeding the concrete in the screeding direction, the control will automatically stop or deactivate the vibrator motor. If the screed head assembly is moved in the opposite or non-screeding direction, the vibrator motor may remain stopped or deactivated. However, when the screed head assembly is again moved in the screeding direction, the control may automatically activate the vibrator motor (and may ramp up the speed of the vibrator motor as discussed above) to continue to vibrate the vibrating member and thus to vibrate and screed the concrete surface as the screed head assembly is moved over and along the concrete surface in the screeding direction. The movement of the screed head assembly may be detected or determined via any sensing means (that may detect movement of the screed head assembly along the concrete surface in the screeding direction) or the like, or the vibrator control may be operable in response to a signal indicative of the screeding machine moving the screed head assembly over and along the concrete surface (such as a signal that is generated in response to actuation of a hydraulic cylinder that causes retraction of the support boom to move the screed head assembly toward the machine), without affecting the scope of the present invention.
Such a vibrator control or system and/or soft start control or system may be implemented with a screeding machine or device of the type shown in
Although several embodiments of the soft landing control system of the present invention have been shown and described herein, these embodiments are exemplary of the present invention, and the present invention is not intended to be limited only to these embodiments. Other soft landing control systems that control the landing or engagement of the vibrating member with the concrete surface to reduce or substantially preclude depressions or irregularities from occurring in or at the previously screeded concrete may be implemented without affecting the scope of the present invention. Also, although shown with hydraulic cylinders or electric actuators, other actuators or motors or the like may be implemented to adjust or control the movement of the screed head assembly and/or the level sensor and/or the vibrating member and the like, without affecting the scope of the present invention. Also, other sensing devices, such as movable sensors or wheels or the like and/or vibration sensors and/or contact switches and/or optical sensors and/or sonic proximity sensors and/or other sensors or sensing means for determining when the vibrator is generally at or near the uncured concrete may be implemented without affecting the scope of the present invention. It is further envisioned that various aspects of the embodiments shown and described herein may be implemented in other embodiments or systems as well or combined with various aspects of the other embodiments, without affecting the scope of the present invention.
Therefore, the present invention provides a soft landing control system that is operable to rotate or pivot the screed head assembly or otherwise adjust or move the vibrator or vibrating member of the screed head assembly into substantial engagement with the concrete surface at an appropriate time and location to limit or reduce or substantially preclude substantial engagement of the vibrator with a previously screeded and partially cured area of the concrete. The present invention thus limits or avoids damage to or irregularities in the concrete surface that may occur if the vibrator engages and depresses against the overlap areas of the concrete surface that have already been screeded. The soft landing control system automatically controls the lowering of the vibrator and may lower the vibrator into substantial engagement with the concrete surface in response to a time delay from the initial lowering of the screed head assembly or from activation of the soft landing control system, such as from a manual input or the like. Optionally, the soft landing control system may automatically control the lowering of the vibrator and may lower the vibrator into substantial engagement with the concrete surface in response to a vibration detection or soft concrete detection that is indicative of the screed head assembly and/or vibrator being moved to an area of the concrete that is uncured and not yet screeded. The soft landing control system thus is operable to automatically lower the vibrator into substantial engagement with the concrete surface in response to an activating or triggering event or signal and at an appropriate time following the activating or triggering event or signal and/or at an appropriate location of the vibrator over the concrete surface. Optionally, the control system may be operable to automatically control the vibrator motor or device in response to movement of the screed head assembly over and along the concrete surface, in order to limit or substantially preclude depressions from being formed in the concrete surface when movement of the screed head assembly is temporarily stopped while the vibrating member is engaged with the concrete surface. When movement of the screed head assembly commences in the screeding direction, the vibrator motor may be activated to begin vibrating the vibrating member, and may be ramped up from an initial low vibration frequency to a higher operational frequency as the screed head assembly is moved over and along the concrete surface.
Changes and modifications to the specifically described embodiments can be carried out without departing from the principles of the present invention, which is intended to be limited only by the scope of the appended claims as interpreted according to the principles of patent law.
The present application is a divisional of U.S. patent application Ser. No. 10/804,325, filed Mar. 19, 2004 by Quenzi et al. (Attorney Docket SOM01 P-322), which claims benefit of U.S. provisional application, Ser. No. 60/457,260, filed Mar. 25, 2003 by Torvinen for SCREED HEAD ASSEMBLY (Attorney Docket SOM01 P-321), which are hereby incorporated herein by reference in its their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 60457260 | Mar 2003 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10804325 | Mar 2004 | US |
| Child | 11404686 | Apr 2006 | US |
