DE3638207A1 - Process for producing purpose-made concrete blocks, and apparatus for carrying out the process - Google Patents

Abstract

The invention relates to a process for producing purpose-made concrete blocks, in which process concrete is filled into moulds, is optionally pre-compacted by vibration and is re-filled with facing concrete, and main compaction subsequently takes place by vibration. The invention also relates to an apparatus for carrying out such a process. In order to improve the process and the apparatus such that the cycle times of the machine are shortened and, at the same time, the quality of the blocks produced is improved, the invention proposes that the vibrations are directional linear vibrations and the entire vibration procedure runs with adjustable frequency and amplitude, and that, in the case of the appertaining apparatus, the vibrator is a linearly vibrating piston vibrator (14) driven by compressed air. <IMAGE>

Description

The invention relates to a method for producing Concrete blocks, in which concrete is filled in molds optionally pre-compacted by shaking and with facing concrete is refilled and then by shaking a main compression takes place.

The invention also relates to a device for manufacturing provision of concrete blocks, consisting of at least a filling station, a compression station with one Vibrating table with at least one vibrator and transport stone directions for the supply and removal of the molds and the concrete stones.

Such methods and devices are known. Here it is common to first use the shapes for the concrete blocks Fill core concrete, the filled forms on the Rüt bring to the table and for a time of at least Pre-compact the concrete by shaking for 0.5 seconds. By this pre-compaction sags the core concrete in the molds, so that subsequently so-called facing concrete in a white tere filling station can be refilled. The refilled ten forms are brought back to the vibrating table where then during a shaking time of at least 2.5 to 3 Se customers the so-called main compression takes place.

The vibrations are generally by eccentrically rotating masses produced by electrical motors are driven. Such an imbalance generates strong vibrations in the rotation with it connected machine parts. These vibrations are ever but more or less undirected and burden them with machine parts connected to the vibrator very strongly. To the Rüttelti is responsible for keeping these loads within limits generally two for concrete block machines  Vibrators are used, the imbalances of which are as equal as possible, however, the unbalanced masses are parallel to each other Axes as synchronously as possible in the opposite direction rotate.

If such vibrators over the vibrating table and / or one Frame are firmly connected, and the unbalance masses rotate in opposite directions so that the masses are heavy points at the same time the highest point on the of reach the circular path described to them, so the Horizontal components of the two opposite Schwin essentially on while the vertical com Overlay components additively. This essentially gives you lichen an up and down movement of the vibrating table, the on the Be in the forms on the table transmits ton and causes its compression.

However, such a machine does not succeed completely homogeneous vertical vibrations of the plate of the Rüt to produce a table. This mainly depends on the He generation of vibrations by rotating masses together. Besides generating the up and down movements of the vibrating table the counter-rotating imbalances of the vibrators too Bending vibrations in the table top as well as compressions and Strains in the plate plane because of the horizontal components th of the associated with the counter rotating masses Centrifugal forces in opposite directions act on the vibrators.

Further difficulties arise with such a Ma seem that the unbalance of the two vibrators must be practically the same and that one is absolutely for one synchronous and in-phase running of the vibrators even when Starting and braking must be taken care of, otherwise enormous forces can occur in the horizontal direction, for which the machines are generally not designed.

Such synchronism can only be achieved through a common one  Make sure the gearbox is appropriately robust must and increases energy consumption.

Another disadvantage of the conventional Betonformsteinma machines is that the start-up and braking times for the individual vibrations already make up a significant part of the total vibrating time, since the actual vibrating or compacting time is relatively short and the acceleration or braking of the rotating unbalanced masses Vibrators cannot be done as quickly as desired. For example, the pre-compression time consists practically only of a start-up and a braking phase of the vibrators, the end frequency and the maximum amplitude often not being reached once, as is shown schematically in FIG. 2a via position D. This also determines the total cycle time, in which the machine can produce a new set of shaped stones, from the start-up and braking times of the vibrators. The productivity of the conventional machines is correspondingly lower with long start-up and braking times of the vibrators.

Another disadvantage of the known method or the known machines is that the vibrations of the vibrating table are not homogeneous, that is to say are not clearly tet and linear. Accordingly, the plate does not perform exactly the same vertical movements over its entire surface, so that the concrete in different areas of the plate is also compacted differently. This is in Fig. 3a, which shows a compaction station 18 in the center with conventional vibrators 14 ', since it is shown that the concrete has not sagged at the edges of the mold 31 , so it is not compacted.

Compared to the known method and devices for Manufacture of concrete blocks is the invention Task based on the method and the device improve that the cycle times of the machine are shortened the and at the same time the quality of the stones produced  is improved overall.

With regard to the method with the above Features this task is solved in that the Rüt are linear vibrations and the entire vibrating process with adjustable frequency and Am plitude expires.

Provided the vibrations are clearly directed linear vibrations, this is equivalent to a völ lig homogeneous and even movement of the surface the vibrating table or the pallet on it, which carries the forms filled with concrete. The Verdich The concrete is thus spread over the entire surface of the Vibrating table evenly, so that the vibrating time or the compression time can be shortened accordingly. At the same time, there is less or no committee at all, because the concrete also compacts well on the outer edge of the form becomes. Therefore, the entire table surface can be covered by ent speaking large shapes are used.

The entire vibrating process runs at an adjustable frequency and amplitude. The optimal frequency is ei on the vibration behavior of the table and the ge entire machine, but also on the thickness or Coordinate the height of the concrete layer to be compacted. That the entire vibrating process with adjustable frequency and Amplitude expires is synonymous with avoidance of start-up and braking times, because during such times the targeted setting of frequency and amplitude is excluded.

According to the invention, a method is preferred for which the vibrating process with constant frequency and kon constant amplitude expires.

For a specific compaction task often prove to be a certain frequency and a certain amplitude as  optimal, which are then to be kept constant and thus a mi allow for minimal compression time.

In the method according to the invention is expedient provided that the vibration time for the pre-compaction ma x 0.3 seconds maximum and the vibration time for the main ver seal is a maximum of 1.8 seconds.

For the compaction of commercially available concrete blocks these times prove to be sufficient. The cycle times the machine can be kept correspondingly short and the specific energy consumption is lower than for Ver drive with longer shaking times.

With regard to the device with the aforementioned Features become the object on which the invention is based solved in that the vibrator is a linearly vibrating, air-driven piston vibrator.

Such a piston vibrator automatically generates exclusion linear vibrations since the piston does not rotate, but only vertically towards it Axis of symmetry moved. With a compressed air driven col benvibrator can with the Ver invention drive the desired vibration processes in an ideal manner realize.

However, compressed air drives compared to the abge given performance a relatively high energy consumption. Des they were half made for processes and devices The provision of molded concrete blocks has not yet been considered moved because the drive motors of the conventional vibrators already have a relatively high energy consumption. In addition, it was not to be expected from the outset that with Piston vibrators a better and more even compaction of the concrete and a reduction in the vibration times to achieve. Theoretically, one also expects for two counter-rotating vibrators one exactly linear  Vibration behavior if both imbalances are exactly the same are large and the opposite rotation in the correct Phasing takes place. The small deviations from the idea system consisting of two identical, however counter-rotating vibrators and an ideally rigid vibrating table, their effects can practically not be predicted beforehand to calculate. In an analogous way, however, one could assume that that go even for a piston vibrator deviations of the precisely linear vibration behavior of the vibrating table would result, so that the factor of energy costs the Rash in favor of the previously used rotating Gave jogger.

Surprisingly, however, it has been shown that the one a compressed air powered piston vibrator a very uniform compaction of the concrete over the entire run table surface can be reached and that by correspond accordingly shortened shaking times also the energy costs per Stone be lowered.

Furthermore, it turns out that in practice, even with the same Chen shaking times the energy consumption of compressed air gear piston vibrators is not significantly higher than that of electrically powered rotating vibrator learn. With electrically powered vibrators, the An running current five times the current consumption in continuous operation be. However, because of the short vibration time, the start-up phase is already a significant fraction of the total high vibration consumption affects the high power consumption when accelerating the rotating mass in considerable Dimensions. In addition, the vibrators with an ex centrically rotating mass enormous wear. The Bearings are heavily loaded by the imbalance, which is often The motor windings and finally the stored rotational energy is through Brakes turned into thermal energy in a very short time, so that brake pads are changed accordingly frequently Need to become. The consequence of these burdens is a high one  Susceptibility to repairs associated with appropriate breastfeeding downtimes of the machine.

In the machine according to the invention with a compressed air driven piston vibrator, on the other hand, you have one clearly less wear. The structure of the piston vibrator is very simple since it is essentially only from the one Cylinder up and down piston exists. Brakes are no more necessary than bearings.

There is a decisive advantage of the piston vibrator further in that the start-up and braking times of the Kol bens are practically zero. Already with the first The piston moves at full amplitude and stroke the full frequency, which for a given mass of the Piston only from the pressure of the supply air and the exhaust air of the Vi depend on brators. Both parameters can be sufficient vary quickly so that the start-up and braking times at the vibration frequencies in question in the Order of magnitude of 50 Hz are practically negligible. Just like the piston with the first stroke, immediately with the vibrates at the correct frequency and amplitude, it also stops without any ringing as soon as the compressed air supply will end.

The elimination of the start-up and braking times is shortened also the entire vibration time. Furthermore, the so-called risk times, i.e. the times one after the braking process of conventional rotating vibrators had to wait for a new step to make sure that the vibrators really stand still because of the braking times during operation due to wear, heat or pollution Cleaning of the brake pads can vary.

The preferred embodiment of the invention includes provided that the compressed air system control devices and valves for setting the oscillation frequency and the Am has plitude.  

Since with one and the same machine in general also un different concrete blocks can be manufactured the vibration behavior of using different concrete change the loaded vibrating table so that the Adaptation of the oscillation frequency and the amplitude to the education optimal compaction results as advantageous points.

It proves to be the case for machines with larger vibrating tables as advantageous and expedient if min at least two similar vibrators on the vibrating table are brought, which by a common compressed air system operate.

This makes it homogeneous even with large vibrating tables Vibration behavior of the table top achieves what Using a single vibrator only by a very stiff and correspondingly complex and heavily constructed Tabletop would be possible. The synchronization of the two (or even several) vibrators take place automatically in that they operate from the same compressed air system are driven, the compressed air chambers of the vibrato communicating with each other. Even with not exactly the same vibrators (for example with something below different piston masses) is due to the compressed air coupling an absolutely synchronous vibration condition poses.

The advantages of the method according to the invention and the proper machine are obvious:

• 1. The cycle times of the machine are shortened, i.e. Per Unit of time can be produced more.
• 2. Repair and maintenance costs are reduced as well like corresponding downtimes.
• 3. Less rejects are produced (curbs).
• 4. The quality of the stones is overall more uniform and better.

In this context, the Ver using a self-reversing piston vibrator without Seals that work practically wear-free.

The noise emission from concrete block machines seems too when using compressed air powered piston vibrators to be diminished, at least it becomes subjective Noise perception improved.

Further advantages, features and possible applications of the present invention will be clearly apparent from the follow the description of preferred embodiments and there associated figures. Show it:

Fig. 1 shows schematically the structure of a piston vibrator in cross-section with a compressed air feed lines,

Fig. 2a shows the diagram of a concrete block machine with forth conventional compression station and

FIG. 2b shows a corresponding compaction station according to the present invention.

Fig. 3a shows the timing of a working cycle of a conventional concrete block machine,

FIG. 3b, the timing of an operating cycle according to the inventive method and entspre sponding machine,

Fig. 1 shows a low-noise compressed air piston vibrator, the piston 4 vibrates against air cushions. The vibrator essentially consists of the base plate 1 , the housing 2 , the cover 3 and the piston 4 . Piston 4 and housing 2 have a circular cross section. The piston 4 swings in the direction of the axis 10 of the cylindrical housing 2 , which also represents the axis of symmetry of the piston 4 .

When the 3/2 directional control valve 5 is opened , the piston 4 starts immediately without delay.

When valve 5 is closed, compressed air line 6 to the vibrator is vented. The piston can therefore no longer reverse and stops immediately.

The frequency can be adjusted by reducing the amount of air supplied by means of a throttle 11 and the pressure drop caused thereby. Similarly, one could use a pressure regulator instead. By throttling the exhaust air in the exhaust air line 8 , the amplitude of the piston 4 can be adjusted when the valve 9 is closed. The amplitude becomes maximum when the valve 9 is fully open, so the exhaust air can escape unthrottled. The throttles 7 and 11 and the valves 5 and 9 can be remotely controlled and optionally operated according to a predetermined automatic sequence.

The arrows in lines 6 and 8 indicate in which direction the compressed air can flow. The double arrow in the compressed air line 6 between the 3/2-way valve 5 and the piston vibrator indicates that when the valve 5 is open, the compressed air flows from a compressor (not shown) into the piston vibrator, while in the position of the three / Two-way valve 5, the line 6 to the compressor is closed, while via the three-way valve 5 there is a connection from the piston vibrator to the outside, so that the compressed air can escape from the vibrator in the opposite direction through the end of the line 6 . The piston 4 then sags to a minimum position in which the air cushion beneath it can no longer escape, since the ventilation openings 21 or the compressed air supply opening 20 are closed by the wall of the piston 4 or the wall of the housing 2 . The piston 4 is slidably guided in the housing 2 without additional seals.

In Fig. 2a a machine for the production of concrete blocks is shown schematically.

Core concrete is dosed into a filling box 23 from a container 24 . A Pa 22 located under the filling box 23 is pushed onto the compression station 18 .

The mold 31 is lowered onto the pallet 22 and then the filling box 23 with core concrete is pushed over the mold 31 , the closure plate 27 forming the bottom of the filling box 23 striking against the edge of the mold 31 and remaining. After retracting the filling box 23 , the form 31 is filled with Kernbe clay up to the top. Now the core concrete is pre-compacted by briefly pressing the vibrator 14 '.

The core concrete sags somewhat as a result of the vibration, as is indicated in FIG. 3a by line 15 , which represents the upper edge of the sagged concrete layer. The vibrators shown in Fig. 2a are conventional Rota tion vibrators, and the line 15 rising to the edges of the shape 31 indicates that in these areas the loading tone is poorly precompressed.

The free space 29 in the form 31 above the core concrete is now topped up in an analogous manner with facing concrete, specifically with the aid of the filling box 30 , which is shown in the position under the container 28 with facing concrete.

In Fig. 3b, only the compression station 18 is shown, which, however, does not have a vibrator with an eccentrically rotating mass but instead a piston vibrator 14 . By the exactly horizontally duri fende line 15 it is indicated that with the help of the piston vibrator 14 a uniform pre-compression of the concrete is achieved over the entire surface of the plate 12 of the vibrating table 13 .

When the volume 29 is filled with facing concrete, the punches 25 are pressed into the mold 31 by means of hydraulic cylinders 17 . At the same time, the vibrator 14 is actuated.

If necessary, further vibrators 26 can also be arranged on the punches 25 . After this main compaction, the stamp 25 and the form 31 are raised, the finished concrete blocks remain on the pallet 22 . This is then pushed out of the system with the stones via the roller conveyor 41 .

Fig. 3 shows the timing of the individual work gears. The workflow is shown in Fig. 3a, as it results when using conventional Rotationsrütt ler, while in Fig. 3b is a work cycle is Darge, in which an air-powered piston vibrator is used. In Fig. 3a, the rotational frequency of the vibrator is plotted against time, while in Fig. 3b the oscillation frequency of a piston vibrator is plotted against time. The individual work processes are marked with large letters A to K.

Here means:

• A = insert pallet 22 into compression station 18 ,
• B = lower form 31 ,
• C = Filling box 23 over form 31 and back (filling form 31 with core concrete),
• D = shaking (pre-compaction),
• E = risk time (to ensure that the rotating Stand still),
• F = Filling box ( 30 ) over form 31 and back (filling space 29 of form 31 with facing concrete),
• G = shaking and pressing (main compaction),
• H = risk time,
• I = pull out form 31 and
• K = extend pallet 22 with concrete blocks.

A comparison of FIGS . 3a and 3b shows that, according to FIG. 3b, no risk times E and H have to be taken into account, since the piston vibrator 14 used stops immediately after the three-way valve 5 is closed . The risk times E and H are each about 0.5 seconds.

The obliquely rising or falling edges in the areas D and G in Fig. 3a correspond to the start-up or braking times of the rotating vibrator 14 '. As you can see, the time for the pre-compaction of about 0.5 seconds for the rotating vibrators is not enough to get into the stationary working area at a constant frequency. This frequency is only reached during the longer main compression period. In contrast, a start-up and braking time for the piston vibrator can practically not be seen in FIG. 3b. The time for the pre-compaction in the area D can therefore be limited to a maximum of 0.3 Se customer, while still better Vorver be seal results than in the longer of continuous Vorverdichtungszeit with the method according to Fi gur 3 a. With the main compression in area G , the times for starting and braking can also be saved if a piston vibrator is used instead of a rotating vibrator. Risk times E and H are also omitted.

A work cycle, which in the example shown in FIG. 3a is designed for 12 seconds, can be shortened to a little more than 10 seconds when using one (or more) piston vibrators. This shortening the work cycle increases the productivity of the machine by more than 15%. At the same time, the need to repair the entire machine is reduced, which results in further cost savings.

Claims (6)

1. A process for the production of concrete blocks, in which concrete is filled into molds, optionally pre-compacted by shaking and refilled with facing concrete and then a main compaction device is carried out by shaking, characterized in that the shaking vibrations are linear vibrations and the entire shaking process is adjustable Frequency and amplitude expires. 2. The method according to claim 1, characterized in that the shaking process with constant frequency and constant ter amplitude expires. 3. The method according to claim 1 or 2, characterized net that the vibration time for pre-compaction is maximum 0.3 seconds and the vibration time for the main compaction tion is a maximum of 1.8 seconds. 4. Device for the production of concrete blocks, be standing from at least one filling station ( 19 ), a compression station ( 18 ) with a vibrating table ( 13 ) with at least one vibrator ( 14 ') and with transport devices ( 1 ) for the supply and discharge the molds ( 3 ) and the concrete blocks, characterized in that the vibrator ( 14 ) is a linearly vibrating piston vibrator ( 14 ) driven by compressed air. 5. The device according to claim 4, characterized in that the compressed air system has control devices and valves ( 5 , 11 , 7 , 9 ) for adjusting the frequency and the amplitude. 6. Apparatus according to claim 4 or 5, characterized in that at least two vibrators ( 14 ) are attached to the vibrating table ( 13 ), which are operated by a common compressed air system.