FI97455C - Method and apparatus for producing a controlled compacted concrete product - Google Patents

Abstract

The present publication discloses a method for producing a concrete product with a controlled degree of compaction by means of on-line measurement of casting condition variables and an apparatus suited to implement the method. The invention is based on measuring and computationally processing the power consumed by the side (12) or top (11) trowelling beam of the casting apparatus, or alternatively, a variable related to said power, and on the basis of the obtained result, controlling the factors affecting the degree of compaction such as the rotational speed of the feed augers (2) and the vibration effect and/or the mechanical trowelling motion of mandrels (3) or other elements. The power consumed for compaction correlates extremely well with the degree of compaction, thereby providing by way of the invention a regulation method for the degree of compaction in the cast material and thus a very satisfactory tool for controlling the quality of the final product. <IMAGE>

Description

97455

The present invention relates to a method according to the preamble 5 of claim 1, by means of which the tightness of the concrete product to be poured can be controlled by measuring the quantities during casting.

The invention also relates to a device according to the preamble 10 of claim 8, by means of which the method can be applied.

Elongated Concrete products, such as hollow core slabs, are usually made on extruder casting machines. The casting machine consists of a conical feed hopper with one of the 15 or more feed screws below. The extension of the screw thread is often a shaped mandrel, which continues as an auxiliary mandrel supporting the cavity made in the product. The shaped mandrel has a vibrator or other compaction device with which the concrete to be poured is compacted to the shape determined by the casting mold and the mandrels. The casting machine 20 also has an upper friction bar forming the upper edge of the mold, and generally the edges of the mold are also formed of side friction beams. The friction bars compact the cast mass and finish the surface of the cast part. Vibration can also be used for compaction in addition to or instead of massage. Extra-25 router casting machines are continuous casting machines that move. on the mold surface forward due to the reaction force caused by the feed screws.

Extruder casting machines are well suited for the serial production of concrete pieces, but the control of the strength properties of concrete products made by known methods is uniform; to produce a quality product has been cumbersome and the production equipment used has been susceptible to damage. Efforts have been made to measure the factors influencing the quality of finished products in many ways. The most commonly measured quantity is the pressure of the mass to be cast in the mold. The mass pressure is measured either directly by suitable sensors or indirectly by 2 97455 by measuring the force exerted by the mass pressure on a part of the device, for example on feed screws, friction beams or other machine parts. Finnish Publication 84575 describes a method and device in which the compaction of concrete is controlled by measuring the pressure of the concrete mass or the force of the mass on a part of the machine and the mass supply and compaction are adjusted on the basis of the measurement result. The mass pressure is measured with pressure sensors.

10

Variations in the strength of the finished product are mainly due to the fact that the mass does not condense in the same way throughout the casting cycle. Condensation is affected by e.g. mass moisture, particle size, and variations in the relative amounts of the various ingredients. For example, a small change in the moisture content of the pulp causes a large change in the density of the final product while other factors remain the same. For this reason, it is very difficult to control the factors affecting the tightness at the pulp manufacturing stage. In practice, the concrete mass is always of the inhomogeneous-20 gene and condenses even when the same body is cast differently in different parts of the body. The casting machines move on the casting base under the influence of the reaction force of the feed screws. The running resistance of the casting machine can vary for many reasons, and as the resistance increases, the feed screws have to compress the mass 25 with a greater force and the cast product becomes tighter. Correspondingly, as the rolling resistance decreases, the mass condenses less. In order to make the finished part homogeneous, it should be possible to measure and control the compaction event of the concrete.

30! The compaction of concrete has been measured indirectly by measuring, for example, the power used to rotate the feed screws or the axial force applied to the feed screws. Such a solution is presented e.g. U.S. Patent Publication No. 35 to 3,175,477. GB patent 1,586,181 describes a solution in which the speed of the casting machine is controlled by means of the power absorbed by the feed screw or the force t ti 3 97455 applied to it. The aim is to make the speed as even as possible, so that the tightness of the concrete to be poured remains the same in all parts of the part. The compaction itself cannot be measured in the apparatus shown in the publication and the density of the final product cannot be adjusted, especially in extruders where the casting machine moves under the reaction forces of the feed screws.

In addition, it is known to measure either the pressure of the mass 10 to be cast directly or the pressure effect exerted by the mass on a part of the device as described in FI 84575. Pressure measurement is known from both concrete casting machines and plastic extruders. U.S. Patent 3,799,719 discloses the measurement of pressure in a plastic extruder.

15 To date, the compaction of the final concrete product has been best controlled by methods based on pressure measurement. However, the pressure during casting is difficult to measure and sensing is expensive to implement. Sensors that directly measure the pressure of the mass 20 to be cast are easily damaged by the concrete being cast. The pressure of the casting mass does not directly correlate with the density of the final product, but is affected by the Theological properties of the mass, such as the composition of the mass, moisture and several other factors, the effect of which cannot be taken into account by any known method. Since the tightness cannot be measured directly at the time of casting, the sealing effect cannot be adjusted to obtain a uniform product. Thus, even the properties of the final product based on tightness, such as strength 30 and dimensional accuracy, cannot be controlled well enough.

The object of the present invention is to provide a new measuring method by means of which the compaction of cast concrete can be measured and by means of this measuring result the operation of the casting machine can be adjusted in order to obtain the desired end product.

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The invention is based on measuring the power taken by the side or top friction bar of the casting machine or a proportion proportional thereto, processing it computationally and adjusting the factors influencing the compaction result, such as feed screw speed or vibration power and / or mechanical frictional movement of the mandrels or other members.

More specifically, the method according to the invention is characterized by what is stated in the characterizing part of claim 1.

The device according to the invention, in turn, is characterized by what is stated in the characterizing part of claim 8.

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The invention provides considerable advantages.

The power used by the friction beam to compact the concrete mass correlates well with the quantities measuring workability and rheology. These properties depend on, among other things, the aggregate, binders and additives and the amount of water in the pulp. For example, the grain size of the pulp strongly affects the workability of the pulp and the amount of compaction work required. Thus, by measuring the compaction performance and adjusting the concrete feed rate based on the measurement result, or compaction parameters such as vibration power or mechanical friction power, casting machine operation, concrete mass pressure and compaction performance can be optimized according to the desired properties of the mass and final product. The upper friction bar extends to most of the 30 most of the tile-like cast product! and the side friction beam, respectively, the compaction area of the beam-like products, so that the measured power gives a very good picture of the total compaction requirement. The power consumption of the casting machine can be optimized to suit each product, thus saving energy costs and avoiding unnecessary strain on the machine, thus reducing wear and tear.

The invention is explained in more detail below with the aid of the accompanying drawings.

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Figure 1 shows a partial casting machine according to the invention in partial section.

Figure 2 is a cross-sectional view of the device of Figure 1 at the friction bar-10e.

Figure 3 illustrates an alternative profile of the product to be manufactured.

Fig. 4 is a block diagram according to which the device control algorithm can be implemented.

The device according to the invention is an extruder casting machine which is adapted to move on the support wheels 5 along the edges of the mold 13. The device is assembled on a frame 4. In this example, the casting machine has three conical feed screws 2. The screws 2 are fitted to the body 4 by means of a rotating screw shaft 7. At the opposite end to the casting direction of the feed screws 2 there are shaped mandrels 3. A drawbar 6 passes through the screw shafts 7, to which a seal drive motor 9 is connected by a crank mechanism 16 and at the screw end a variator drive 17 with which the screw 2 drive motors is a conical mass feed hopper 1. After the feed hopper 1 in the direction I opposite to the casting direction, there is an upper friction bar 11 on the top and lower friction bars 12 on the sides. From the drive motor 10 of the upper rotation beam, the measuring line 19 leaves the control device 18, 6 97455 and from there further the control lines to the screw drive 8 and the seal drive. The control of the drive devices can be implemented, for example, by means of a variator or inverter or by using other known techniques.

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The device works as follows. The concrete fed to the pulp tank 1 flows to the feed screws 2, which are rotated by the drive device 10. The rotating screws 2 push the concrete into a pressurized space which continues as a forming space delimited by the mold 13, side friction beams 12 and upper 10 friction beams 11. In this state, the concrete is compressed between the forming mandrels 3 and the walls delimiting the forming space l1, 12, 13 and compacts by the movement and pressure of the forming mandrels 3 and the friction beams 11, 12 and forms into the desired end product 14, e.g. The reciprocating movement of the shaped mandrels 3 is effected by an electric motor 9 which is connected to the end of the drawbar 6 by means of a gear and a crank mechanism 16. The movement of the upper friction beam 11 and the side friction beams is realized by similar electric motor / crank mechanisms 10, 20 15 and 10 ', 22.

The device is adjusted so that the power absorbed by the drive motor 10, 10 'of the upper friction bar 11 and / or the side friction bar 12 is measured either directly or indirectly. The quantity to be measured can be, for example, electric current or hydraulic oil pressure and is selected according to the actuators and control unit used. In the manufacture of the hollow beams and similar plate-like products shown in Fig. 2, the power of the drive motor 10 of the upper friction bar and 30 products such as those shown in Fig. 3, such as I-beams, are preferably measured. with a lower width to height ratio, the power consumption of the drive motors 10 'of the side friction beams is most preferably measured during manufacture.

35 The power measured from the drive motor, or a value proportional to it, describes well the energy required to compact concrete 7 97455 aa, as well as how much energy is needed to achieve the desired result. If the stiffness of the mass increases, then the power consumption increases and at the same time the pressure in the sealing space increases. Similarly, if the grain size of the pulp increases or the proportion of 5 crushed materials in the pulp is increased, the machinability of the pulp decreases and the power consumption of the drive motors increases.

The measurement result is fed to the control unit 18 and the unit 18 calculates the control values by which the rotation speed 10 of the screws 2 or the sealing speed of the shaped mandrels or both are adjusted. The adjustment is generally based on the fact that when the speed of rotation of the screws 2 is slowed down, the pressure in the sealing and shaping mode decreases, and when the sealing speed of the mandrels 3 is increased, the pressure also decreases. As the pressure decreases, the power demand 15 decreases, so there is a clear relationship between the power demand, the pressure and the condensing energy.

Fig. 4 is a block diagram of an adjustment example in which the speed of the two feed screws 2 and the impact frequency of the shaped mandrels 3 20 are adjusted on the basis of the electric current taken by the drive motor 10 of the friction bar 11. The adjustment is periodic, i.e. the system measures the current at certain intervals tp. If the measured current mlp is not within the permissible range, i.e. the measurement result is greater than the sum of the current setting / lp value lp of the friction bar drive motor 10 and the permissible deviation Ips, proceed to the next step. Otherwise, return to the beginning without adjustment. The next step is to check whether the time Tim r used to adjust the feed screw variators is less than the maximum allowable adjustment time te. If this is not the case, 30 will go into an alarm, at which point the device will stop and alarm ·! to the operator's seat. If the adjustment time of the variators is sufficiently short, it is checked whether the measured current mlp is greater than the sum of the current setpoint lp and the upper deviation limit Ipu. If the current is higher, it is checked whether it exceeds the 35 extreme value and in a positive case it is started via alarm and stop. If the extreme value is not exceeded, the stroke frequency of the 8 97455 mandrel seal is increased for a predetermined adjustment time ttt. If, on the other hand, the current mlp is less than the sum of the set value lp and the upper limit of the deviation Ipu, the rotation speed of the screws 2 is decelerated in the next step by a preset adjustment time trt of the screws 5. Next, the mutual rotational speed of the screws 2 is checked by comparing the absolute value of the difference between their measured currents mil and mI2 with the permissible deviation Ird. If the absolute value of the difference is small enough, return to the beginning, otherwise the 10 second screws are decelerated by their mutual preset adjustment times.

In addition to the above, the present invention has other embodiments.

15

Any sufficiently powerful actuator can be used as the actuator. However, the above-mentioned electric and hydraulic motors are best suited for this application. Converting rotary motion to periodic-linear motion can be accomplished in many ways, for example, by crank or eccentric mechanisms. All actuators can be adjustable, but in the simplest solution it is sufficient that the speed of rotation of the screws 2 or the sealing speed of the mandrels 2 is adjustable.

The feed by means of the screws 2 can be replaced by another adjustable feed method, for example a piston feed. A shaped mandrel is not necessarily required, but sealing can take place with tapered mandrels when a cavity is not desired for the product to be cast. Other compaction methods, such as high-frequency vibration, can be used as a replacement for mandrels. The shaped mandrels can also be separated from the feed screws, whereby they operate separately and the screws feed the mass between the mandrels.

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The sealing movement or sealing power can be adjusted by adjusting the speed, stroke length or vibration power of the sealing movement.

Claims (10)

A process for producing a controlled compressed concrete product, wherein 5 - concrete pulp is fed with at least one feeder (2) through a limited cross-section to produce a concrete product (14) of the desired shape, and 10 - the mass to be casting is compressed by means of at least one mechanical, almost rectilinear reciprocating motion, and 15. the power that the mechanical, nearly rectilinear reciprocating motion uses, is measured in a suitable manner and on the basis of the the obtained measurement result is at least regulated by the compression movement or the input of pulp to control the compression effect and the pressure in the region of the limited cross-section, characterized in that the rectilinear movement, the effect of which is measured, is constituted by a grinding movement, which smoothes and compresses the surface of the concrete product and whose consumption effect is determined by measuring the consumption effect of the actuator which achieves the movement. A method according to claim 1, wherein the mass is compressed by moving at least one surface (11) which limits the transverse surface, in motion, characterized in that the power to be measured is the power absorbed by the actuator, which moves this surface (11) in motion. The method of claim 1, wherein pulp is fed through the restricted cross-section and compressed by moving at least one cross-sectional restricting mandrel (3) arranged in reciprocating motion, characterized in that both the feed and the pulp are fed. the compression of the pulp is regulated on the basis of the measurement result by the movement of the mandrel (3). 10 The method of claim 1, wherein pulp is fed through the restricted cross-section and compressed by moving at least one cross-sectional restricting mandrel (3) and three restricted surfaces (11, 12) which restrict the cross-section in forward motion. back, characterized by the fact that the power needed to move all three surfaces (11, 12) is appropriately measured and the input of the pulp is regulated on the basis of the obtained measurement results. 20 5. A method according to claims 3 and 4, characterized in that both the input and the compression of the pulp are controlled on the basis of the measurement result. . 25 Method according to any of the preceding claims, characterized in that the quantity intended for measurement is the current taken up by an electric motor. Process according to any one of the preceding claims, characterized in that the quantity for measurement is the pressure of a hydraulic fluid. 8. Apparatus for producing a controlled compressed concrete product comprising: - at least one feeder means (2) for feeding IT into a restricted cross section, - at least one cross section limiting surface (3, 11, 12). ), which can be put into a mechanical, almost rectilinear reciprocating motion for compressing concrete, and - means (10, 15) for moving the surface, characterized by - means (19) for moving means (3, 11, 12), which equalize and compress the surface of at least one piece to be manufactured, in motion, for measurement, transmission and processing (18), of the power absorbed by the arranged actuator for providing a control value and feeding (20) the control value of at least 1 of the feed means (2, 8, 17) for the concrete. 20 Apparatus according to claim 8 comprising at least one mold mandrel (3) extending to the limited cross-section, and means (9, 16) for moving the mandrel (3) in reciprocating motion, characterized by: means (21) for inputting the control value into the means (9, 16) which move the mandrel (3) in motion to control the compression action of the mandrel. The device of claim 9, wherein the restricted cross-section is limited by a mold (13), two slidable beams (12) displaceable by the actuating means (10 ') and a movable top grinding beam (11) by the actuating means (10) and at least one mold mandrel (3). ), characterized by means (19) for measuring the power absorbed by the actuators of the grinding beams (11, 12).