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(11) | EP 0 353 661 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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Concrete block molding machine having continuously driven vibrating shaft mechanism which can be programmably vibrated and method of programmably vibrating such machines Maschine zum Formen von Betonblöcken mit kontinuierlichem Drehantrieb einer programmierbar erregten Vibrationsvorrichtung sowie Verfahren zur programmierbaren Vibration solcher Maschinen Machine de moulage de blocs en béton ayant un dispositif de vibration à arbre continuellement entraîné programmable et méthode pour programmer les vibrations dans de telles machines |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] The invention relates to a concrete block molding machine comprising
a) a vibratible frame with a mold box incorporating molding cavities therein for a concrete mix which is to be densified in the cavities,
b) at least one vibration causing shaft assembly supported on said frame to impart vibrating motion thereto,
c) bearings on said frame for journaling the ends of said shaft assembly,
d) drive means connected with said shaft assembly for driving said shaft assembly in continuous rotation,
e) said shaft assembly comprising opposite end stubs having circumferentially fixed portions eccentric to the axis of rotation of said shaft assembly and a circumferentially movable balancing mass for movement between a first circumferential position in which said balancing mass substantially balances the centrifugal force imparted eccentrically by said eccentric portions of said end stubs to produce a null level of vibration and a second circumferential position in which densifying vibration is produced, the said balancing mass in the first position being substantially 180° opposite the eccentric portions of said end stubs,
[0002] A concrete block molding machine of the above-mentioned kind is known from US-A-4,312,242. The vibration assembly of this machine cannot be adjusted during operation.
[0003] GB-A-2,108,235 and AT-A-375 845 both disclose vibration assemblies that can be adjusted during operation.
[0004] The weights of the machine disclosed in GB-A 21 08 235 are driven by one pin which is exposed to the elements. There is no rigid central support shaft to support the weights and to transfer vibrations. An outer drum is supported by bearings which are supported by an inner drum.
[0005] The vibration member disclosed in AT-A-375 845 has a hollow central shaft and a tube member supported on the hollow central shaft by bearings. Weights are attached directly to the hollow shaft and to the tube member. A single pin drives the weights provided on the tube member.
[0006] In prior art machines in which the eccentric shafts producing the vibration have been stopped to halt the vibration at the end of the densifying step, large brakes have been required to stop the shafts. Moreover, because of the rapid acceleration and deceleration required in contemporary high production machines, as much as four times the horsepower required to produce the vibration had to be utilized, with the result that much larger motors and shafts were required for reasons other than producing the vibration. In machinery of the type disclosed in US-A-4 312 242, the vibrating shaft in effect coasts between intervals of operation of the drive motor and so need not be braked and brought up to full speed from a static position. However, the machine still operates by starting and stopping the drive motor and a substantial acceleration of the coasting shaft is required at the time it is desired to produce vibration. Moreover, such prior art machinery is not versatile in the sense that the amplitude of vibration and the forces exerted can be varied during the vibration portion of the cycle.
[0007] The invention is directed to a high speed, concrete products forming machine which can be utilized in production operations for manufacturing a variety of shapes from a variety of aggregates. Certain intensities and patterns of vibration are optimally used for any given mold, shape of product, or aggregate mix which is used.
[0008] It is the object of the present invention to provide a machine and a method which encourage the programming of the best cycle parameters for a particular "run" so that the same parameters can be stored in the memory of a programmable logic controller and used in future runs of a particular product.
[0009] Furthermore, it is the object of the invention to provide a system in which the vibrating shaft assembly can be rotated continuously at vibrating speed without the need for intermittent starting, stopping, and braking while providing the capability of changing the amplitude of the vibration during the operating cycle, and even during the product densifying portion of the cycle.
[0010] According to the invention this object is solved by a machine characterised by the following features:
f) said balancing mass is mounted for rotation on said end stubs,
g) one of said end stubs is recessed to provide a piston cylinder with a piston therein,
h) means are provided interconnecting said piston and said balancing mass to produce rotary motion of said balancing mass relative to said end stubs with axial movement of the piston in said cylinder, to move said balancing mass from said first balancing position in relation to said eccentric portions toward an offset circumferential position,
i) spring means of predetermined rate are provided opposing axial movement of said piston and operative to move said piston in an opposite direction to restore said piston and said balancing mass when pressure on the piston is released,
k) fluid pressure supply means are provided for supplying fluid under a predetermined pressure to one end of said piston in opposition to said spring means to control the axial position of said piston and consequentially the circumferential position of said balancing mass relative to said eccentric portions of said end stubs.
[0011] Further improvements of this machine are subject matter of claims 2 to 7. Claims 8 to 16 relate to the method of molding concrete blocks in accordance with the present invention.
[0012] of The invention provide a system of the character described which utilizes a pair of vibrating shaft assemblies which can be so controlled that the vibration occurs in absolute synchronism.
[0013] In this system the amplitude of vibration can be varied during the cycle to compensate for the fact that the total weight of the molding system being vibrated changes during the forming cycle.
[0014] The invention provides a system which contains a shaft assembly whose strength is not compromised intermediate its span, and which can compactly handle the high loads involved in a most efficient and reliable manner.
[0015] Furthermore, the invention provides a quiet system which provides a high density block with low power consumption, and consequently is economical to operate.
[0016] According to the invention the system utilizes a spring having a predetermined rate to opposing the axial movement of the weight position adjusting piston-cylinder assembly in a manner such that the spring mechanism is operative to restore the vibration inducing mass to a desired or null position.
[0017] An embodiment of the invention is shown in the accompanying drawing.
Figure 1 is a schematic, fragmentary, perspective elevational view of the block making machine, showing the mold and the mold vibrating mechanism thereof;
Figure 2 is a fragmentary, sectional, elevational view, illustrating one of the identical mold vibrating shaft assemblies which is employed in a null mode;
Figure 3 is a transverse sectional view thereof, taken on the line 3-3 of Figure 2; and
Figure 4 is a graph indicating vibration intensity in terms of percentage of maximum amplitude versus cycle time.
[0018] Referring now more particularly to the accompanying drawing and in the first instance to Figure 1, a block making machine, generally designated M, of is illustrated fragmentarily. The machine may be considered to include a multi-compartmented mold box, generally designated 10, comprising side members 10a, end members 10b, and divider or partioning plates 11. In addition, core members 12, such as roof top cores, are provided in the compartments defined by the divider plates 11 for the purpose of forming the core openings in the concrete blocks which may, for example, be formed in this particular mold box.
[0019] The lower end of the mold box 10 is, during the forming cycle, closed by a vertically raisable pallet which is releasably clamped to the lower end of the mold box to vibrate with it by a raisable platen having a rubber block top. The upper end of the mold box is open to the reception of concrete mix material from a feed box at the beginning of the cycle. Stripper members are utilized in the usual manner at the end of the cycle to push the blocks formed from the mold as the pallet lowers to a conveyor which moves the green block to a curing area such as a kiln.
[0020] As shown, the mold box 10 has mold supporting side arms forming vibratible frame 13. Spanning the ends of the side arms are twin vibrator shaft assemblies, each generally designated S, and being shown more particularly in Figures 2 and 3. As illustrated, a shaft assembly S is provided at each end of the mold box and both vibrating shaft assemblies are controlled to operate synchronously so that one end of the mold is not vibrated more intensely than the other. This is necessary to ensure uniformity in the blocks being formed in the mold. As Figure 2 particularly indicates, the side arms of the frame 13 support bearings 14 which journal each shaft S for rotation. Each shaft assembly S incorporates a shaft 15 which, at one end, has a solenoid operated variator drive sheave 16 fixed to it in the usual manner for receiving a drive belt 17. Drive belts 17 are driven by an electric, or other suitable, motor in the usual manner at the same speed of rotation but the speed of rotation of each may be adjusted equally with adjustment of the sheaves 16. Mounted on each of the drive shafts 15 to rotate therewith, are opposite end stubs 18 and 19 which, it will be noted in Figure 2, have portions eccentrically disposed relative to the axis x to provide offset weight portions 18a and 19a. Locking ring assemblies 20 secured by bolts 21 are provided in end recessed portions 22 in the end stub 18 and 19 to unite the shaft 15 and the end stubs 18 and 19 for conjoint rotation. The end stubs 18 and 19 are also recessed as at 23 to receives roller bearings 24 supporting a circumferentially movable collar 25 which also as a weight portion eccentric with respect to axis x and forming a balancing mass 25a which is equal in weight to the combined weigth of eccentric portions 18a and 19a of end stubs 18 and 19. The offset weights of the collar 25 and end stubs 18 and 19, thus, balance one another in the Figure 2 position when the balancing mass 25a is 180° removed from the eccentric portions 18a and 19a of end stubs 18 and 19.
[0021] The inner end of end stub 19 is concentrically bored to form a cylinder C in which the reduced end 26a of a shouldered piston 26 is received. At its opposite end, piston 26 is annularly recessed as at 27 to provide a spring well for one end of a coil spring 28 whose opposite end is received in a spring well 29 provided in the end stub 18. Axial guide pins (not shown) may be provided for the spring 28.
[0022] Weight collar 25 is rotatable on bearings 24, from a position 180° removed from the eccentric portions of end stubs 18 and 19 in which the balanced condition is achieved and no vibration is transmitted to bearings 14, through 180°, for example, to a position in which maximum vibration is transmitted to the bearings 14 because the eccentric weight portions 18a, 19a and the balancing mass 25a are in a position of circumferential alignment.
[0023] Provided in the collar 25, is a bore 30 receiving a roller 31 mounted on a pin 32 whose inner end is received in a helical groove 33 provided in the piston 26. The helical groove 33 extends 180° in piston 26 to rotate collar 25 from a null position to a position in which maximum vibration is achieved, when the piston 26 is moved from the null position in which it is shown in Figure 2 from right to left against the bias of spring 28.
[0024] Provided in the shaft 15, is an axial bore 34 connecting with the radial bore 35 leading to the one end 26b of cylinder C. It is to be understood that air under a controlled pressure may be transmitted through a stationary coupling 36 within which reduced shaft end 15a is rotatable. While air is disclosed as the pressure transmitting medium it should be understood that other suitable fluids may be employed. As Figures 1 and 2 indicate, an air hose 37 leading to each shaft assembly S from air dispensing valve 38 is employed to supply air under the pressure desired for a particular operation to the cylinder C. Solenoid operated valve V, which has ports venting to atmosphere, is controlled by a programmable logic controller PLC. Spring 28 is of a predetermined rate, and its compression to the desired degree to achieve the intensity of vibration desired, is determined by the pressure of the air admitted via bores 34 and 35. This pressure is varied by the control 38 during each cycle of the machine when it is determined, for instance, to operate the machine in accordance with a cycle such as disclosed in Figure 4 (which will be later described). Seal rings 39 are provided to seal the cylinder C. The capability that the machine enjoys of achieving optimum intensity of vibration for the particular operation being performed, provides a machine which can often be adjusted to decrease the noise of operation of the machine, where this is desirable. The machine is capable of vibration at an increasing intensity during the filling of the mold from a feed box FB to achieve the desired uniformity of filling which promotes uniformity in the compaction portion of the cycle.
[0025] A typical cycle of operation is diclosed in Figure 4 where it will be noted that approximately a half a second is required to move the material feed box over the empty mold. During this time, each drive shaft 15 is being continuously driven at the selected speed by drive sheave 16 and the collar 25 of each shaft assembly S is in the position indicated in Figure 2 in which the balancing mass 25a of collar 25 counterbalances the eccentric portions 18a and 19a of end stubs 18 and 19 which rotate with the shaft 15. When the feed box is in position, air under the predesignated pressure, is fed from the valve 38 through bores 34 and 35 to move the pistons 26 from right to left in Figure 2 to the extent of 70% of their permissable movement. This revolves the collar 25 through about 126° and achieves an intensity of vibration equivalent to about 70% of maximum, due to the composite offset effect of the balancing mass 25a of collar 25 with respect to the eccentric portions 18a and 19a of end stubs 18 and 19. This intensity is increased slightly before rising to full intensity. The spring 28 of predetermined rate controls the axial position of piston 26. With this sytem as, for instance, opposed to a double-acting hydraulic system, there is no need to return oil to a reservoir (which takes time). Further the presence of air in a hydraulic line, variations in oil temperature, and line leaks, which all can affect the metered volume are not problems. The control achieved is particularly critical in machines in which a pair of shafts must operate in synchronism and a common valve needs to be used to ensure that they actuate at the same instant.
[0026] Figure 4 demonstrates that filling is completed in two seconds and the air pressure admitted through bores 34 and 35 is increased to move the piston 26 further from right to left to a position in which the balancing mass 25a of collar 25 and the eccentric portions 18a and 19a of end stubs 18 and 19 are in alignment so that maximum vibration is exerted during rotation of the shaft assemblies S. At the end of four seconds the supply of air through bores 34 and 35 is cut off, and the air pressure in these bores is bled to atmosphere via valve 38 so that spring 28 restores the piston 26 to the Figure 2 position with balancing mass 25a and eccentric portions 18a , 19a now in a balanced or null position. No vibration is transmitted via the bearings 14 to the mold box 10 at this time when stripping of the product from the mold is being accomplished, even though the shaft 15 continues to be driven at the designated speed. With the present construction, the drive belts 17 need not be started and stopped, and no brakes need be utilized. The vibration obtained is virtually vertical in character with no destabilizing lateral characteristics.
[0027] While one cycle has been illustrated, many others will be used. Typically filling will take place in from 3/4 to 2-1/2 seconds and compaction from 1-1/2 to 3-1/2 seconds. The speed of rotation of shafts 15 can also be varied by the PLC via adjustment of the sheaves 16 to change the frequency of vibration. The program for a given operation will consider both the frequency and amplitude of vibration.
a) a vibratible frame (13) with a mold box (10) incorporating molding cavities therein for a concrete mix which is to be densified in the cavities,
b) at least one vibration causing shaft assembly (S) supported on said frame (13) to impart vibrating motion thereto,
c) bearings (14) on said frame (13) for journaling the ends of said shaft assembly,
d) drive means (16) connected with said shaft assembly (S) for driving said shaft assembly (S) in continuous rotation,
e) said shaft assembly (S) comprising opposite end stubs (18, 19) having circumferentially fixed portions (18a, 19a) eccentric to the axis of rotation of said shaft assembly (S) and a circumferentially movable balancing mass (25a) for movement between a first circumferential position in which said balancing mass (25a) substantially balances the centrifugal force imparted eccentrically by said eccentric portions (18a, 19a) of said end stubs (18, 19) to produce a null level of vibration and a second circumferential position in which densifying vibration is produced, the said balancing mass (25a) in the first position being substantially 180° opposite the eccentric portions (18a, 19a) of said end stubs (18, 19),
characterized by the following features:f) said balancing mass (25a) is mounted for rotation on said end stubs (18, 19),
g) one of said end stubs (18, 19) is recessed to provide a piston cylinder (C) with a piston (26) therein,
h) means (30, 31, 32, 33) are provided interconnecting said piston (26) and said balancing mass (25a) to produce rotary motion of said balancing mass (25a) relative to said end stubs (18, 19) with axial movement of the piston (26) in said cylinder (C), to move said balancing mass (25a) from said first balancing position in relation to said eccentric portions (18a, 19a) toward an offset circumferential position,
i) spring means (28) of predetermined rate are provided opposing axial movement of said piston (26) and operative to move said piston (26) in an opposite direction to restore said piston (26) and said balancing mass (25a) when pressure on the piston (26) is released,
k) fluid pressure supply means (34, 35, 36, 37, 38) are provided for supplying fluid under a predetermined pressure to one end of said piston (26) in opposition to said spring means (28) to control the axial position of said piston (26) and consequentially the circumferential position of said balancing mass (25a) relative to said eccentric portions (18a, 19a) of said end stubs (18, 19).
- a vibratible frame (13) with a mold box (10) incorporating at least one molding cavity for a concrete mixture which is to be densified in said cavity,
- at least one vibration-causing shaft assembly (S) supported on said frame (13) to impart vibrating motion thereto,
- bearings (14) on said frame (13) for journaling the ends of said shaft assembly,
- a drive (16) connected with said shaft assembly (S) for driving said shaft assembly in continuous rotation,
- said shaft assembly (S) mounting a circumferentially fixed portion (18a, 19a) eccentric to the axis of rotation of said shaft assembly and a circumferentially movable balancing mass (25a) mounted for relative rotation with said first eccentric portion (18a, 19a) on said shaft assembly (S) between circumferential positions, in a first of which said balancing mass (25a) substantially balances the centrifugal force imparted eccentrically by said eccentric portion (18a, 19a) to produce a null level of vibration, and in a second position of which densifying vibration is produced, said balancing mass (25a) in said first position being substantially 180° opposite said eccentric portion (18a, 19a),
- said shaft assembly (S) having a cylinder (C) with a piston (26) therin, one of which being axially movable relative to the other,
- means interconnecting said axially movable one of said cylinder (C) and piston (26) with said balancing mass (25a) to produce rotary motion of said balancing mass (25a) in one circumferential direction relative to said eccentric portion (18a, 19a) to move said balancing mass (25a) from a balancing position relative to said eccentric portion (18a, 19a) toward an offset circumferential position,
- spring means (28) of predetermined rate opposing axial movement of said movable one of said piston (26) and cylinder (C) and operative to move it in an opposite direction to restore said balancing mass (25a),
- and fluid pressure supply means (38) for supplying fluid under a predetermined pressure to said cylinder (C) in opposition to said spring means (28) to control the axial position of said movable one of said piston (26) and cylinder (C) and consequentially the circumferential position of said balancing mass (25a) relative to said eccentric portion (18a, 19a),
said method being characterized by the following steps:a) supplying said concrete mixture to said molding cavity for densification during a predetermined time period of a cycle,
b) continuously driving said shaft assembly (S) at a predetermined speed,
c) cyclically over said predetermined time period successively introducing fluid under a predetermined variable pressure to said cylinder (C) and piston (26) in opposition to the force exerted by said spring means (28) to relatively move said balancing mass (25a) and said eccentric portion (18a, 19a) from substantially a position of 180° circumferential opposition in which the vibration produced is substantially null to a substantial vibration producing position out of substantial centrifugal balance to produce densifying vibration having an intensity during a predetermined first portion of said time period in which said mold cavity is supplied with said concrete mixture to be molded,
d) thereafter introducing additional fluid under pressure to said cylinder (C) and piston (26) in opposition to said force exerted by said spring (28) to relatively move said balancing mass (25a) and said eccentric portion (18a, 19a) to a position further removed from said position of 180° circumferential opposition in which said densifying vibration produced is of greater intensity during a second portion of said time period than during said first portion of said time period, and in which said second portion of said time period a final densifying of said concrete mxiture supplied to said mold cavity occurs to produce a molded product,
e) and then removing said fluid introduced to said cylinder (C) and piston (26) to restore said balancing mass (25a) to a position of 180° circumferential opposition such that said vibration produced is substantially null and stripping said molded product from said mold box (10) during a third portion of said predetermined time period of said cycle.
a) einen Vibrationsrahmen (13) mit einem Formgehäuse (10), das darin ausgebildete Formvertiefungen für ein Betongemisch enthält, das in den Vertiefungen zu verdichten ist,
b) wenigstens eine vibrationserzeugende Wellenanordnung (S), die vom Rahmen (13) getragen wird und hierdurch auf diesen eine Vibrationsbewegung überträgt,
c) Lager (14) am Rahmen (13) zur Lagerung der Enden der Wellenanordnung,
d) mit der Wellenanordnung (S) zum kontinuierlichen Rotationsantrieb der Wellenanordnung (S) verbundene Antriebseinrichtungen (16),
e) wobei die Wellenanordnung (S) entgegengesetzte Endansätze (18, 19) enthält, die in Umfangsrichtung fest angeordnete Bereiche (18a, 19a), die exzentrisch zur Rotationsachse der Wellenanordnung (S) stehen, sowie eine in Umfangsrichtung bewegbare Ausgleichsmasse (25a) aufweisen, die beweglich ist zwischen einer ersten Umfangsposition, in der die Ausgleichsmasse (25a) im wesentlichen die Zentrifugalkraft ausgleicht, die exzentrisch durch die exzentrischen Bereiche (18a, 19a) der Endansätze (18, 19) übertragen wird und hierdurch einen Vibrations-Nullwert erzeugt, sowie einer zweiten Umfangsposition, in der eine verdichtende Vibration erzeugt wird, wobei die Ausgleichsmasse (25a) in der ersten Position im wesentlichen um 180° den exzentrischen Bereichen (18a, 19a) der Endansätze (18, 19) entgegengesetzt ist,
gekennzeichnet durch folgende Merkmale:f) die Ausgleichsmasse (25a) ist zur Rotation auf den Endansätzen (18, 19) befestigt,
g) einer der Endansätze (18, 19) ist mit einer Aussparung versehen, durch die ein Kolbenzylinder (C) gebildet wird, in dem sich ein Kolben (26) befindet,
h) Einrichtungen (30, 31, 32, 33) sind vorgesehen, die den Kolben (26) mit der Ausgleichsmasse (25a) verbinden und hierdurch eine relative Rotationsbewegung der Ausgleichsmasse (25a) gegenüber den Endansätzen (18, 19) mit einer Axialbewegung des Kolbens (26) im Zylinder (C) erzeugt, so daß die Ausgleichsmasse (25a) aus der genannten ersten Ausgleichsposition relativ zu den exzentrischen Bereichen (18a, 19a) in eine vergesetzte Umfangsposition bewegt wird,
i) eine Feder (28) vorgegebener Federstärke ist vorgesehen, die der Axialbewegung des Kolbens (26) entgegenwirkt und auf den Kolben (26) in einer entgegengesetzten Bewegungsrichtung einwirkt, so daß der Kolben (26) und die Ausgleichsmasse (25a) zurückgeführt werden, sobald der Druck auf den Kolben (26) wegfällt,
k) es sind Druckfluid-Einrichtungen (34, 35, 36, 37, 38) zur Zuführung eines Fluids vorgesehen, die ein Fluid unter einem vorbestimmtem Druck an ein Ende des Kolbens (26), der Feder (28) entgegenwirkend, zuführen, um die Axial-Position des Kolbens (26) und folglich die Umfangsposition der Ausgleichsmasse (25a) relativ zu den exzentrischen Bereichen (18a, 19a) der Endansätze (18, 19) steuern.
- einen Vibrationsrahmen (13) mit einem Formgehäuse (10), das wenigstens eine Formvertiefung für ein Betongemisch enthält, das in der Vertiefung zu verdichten ist,
- wenigstens eine vibrationserzeugende Wellenanordnung (S), die von dem Rahmen (13) getragen wird, so daß sie auf diesen eine Vibrationsbewegung überträgt,
- Lager (14) am Rahmen (13) zur Lagerung der Enden der Wellenanordnung,
- einen mit der Wellenanordnung (S) verbundenen Antrieb (16) zum kontinuierlichen Rotationsantrieb der Wellenanordnung,
- wobei die Wellenanordnung (S) einen in Umfangsrichtung fest angeordneten Bereich (18a, 19a), der exzentrisch gegenüber der Rotationsachse der Wellenanordnung steht, sowie eine relativ drehbar angeordnete, in Umfangsrichtung bewegliche Ausgleichsmasse (25a) trägt, die zwischen Umfangspositionen relativ beweglich gegenüber dem ersten exzentrischen Bereich (18a, 19a) der Wellenanordnung (S) angeordnet ist, wobei in einer ersten dieser Positionen die Ausgleichsmasse (25a) im wesentlichen die Zentrifugalkraft ausgleicht, die durch den genannten exzentrischen Bereich (18a, 19a) exzentrisch übertragen wird und hierdurch einen Vibrations-Nullwert erzeugt, während in einer zweiten Position eine verdichtende Vibration erzeugt wird, und wobei die Ausgleichsmasse (25a) in der ersten Position im wesentlichen um 180° gegenüber dem exzentrischen Bereich (18a, 19a) entgegengesetzt ist,
- wobei die Wellenanordnung (S) einen Zylinder (C) mit eine darin gelagerten Kolben (26) enthält, wobei einer von diesen gegenüber dem anderen axial beweglich ist,
- Einrichtungen, die den axial beweglichen Zylinder (C) bzw. Kolben (26) mit der Ausgleichsmasse (25a) verbinden und hierdurch eine Rotationsbewegung der Ausgleichsmasse (25a) in einer Umfangsrichtung gegenüber dem exzentrischen Bereich (18a, 19a) erzeugt, so daß die Ausgleichsmasse (25a) aus einer Ausgleichsposition relativ zum exzentrischen Bereich (18a, 19a) in Richtung auf eine abgesetzte Umfangsposition bewegt wird,
- eine Feder (28) von vorgegebener Federstärke, die der Axialbewegung des beweglichen Kolbens (26) bzw. Zylinders (C) entgegenwirkt und in einer entgegengesetzten Richtung bewegbar ist und hierdurch die Ausgleichsmasse (25a) zurückführt,
- und Druckfluid-Einrichtungen (38) zur Zuführung von Fluid unter einem vorgegebenen Druck an den Zylinder (C) entgegen der Schraubenfeder (28), um hierdurch die Axialposition des beweglichen Kolbens (26) bzw. Zylinders (C) und folglich die Umfangsposition der Ausgleichsmasse (25a) gegenüber dem exzentrischen Bereich (18a, 19a) zu steuern,
gekennzeichnet durch folgende Verfahrensschritte:a) das Betongemisch wird der Formvertiefung zur Verdichtung während einer vorgegebenen Zeitspanne eines Zyklus zugeführt,
b) die Wellenanordnung (S) wird mit vorgegebener Geschwindigkeit kontinuierlich angetrieben,
c) zyklisch über die vorgegebene Zeitspanne wird sukzessiv Fluid unter einem vorgegebenen, variablen Druck dem Zylinder (C) sowie dem Kolben (26) entgegen der durch die Feder (28) ausgeübten Kraft zugeführt und hierdurch die Ausgleichsmasse (25a) sowie der exzentrische Bereich (18a, 19a) aus einer Gleichgewichtsposition mit im wesentlichen 180° Umfangsopposition, in der die erzeugte Vibration im wesentlichen gleich Null ist, in eine Position mit erheblicher Vibrationserzeugung außerhalb des substantiellen Zentrifugalgleichgewichts bewegt und hierdurch eine verdichtende Vibration erzeugt, die während eines vorbestimmten ersten Bereichs der Zeitspanne eine Intensität aufweist, in der die Formertiefung mit dem zu formenden Betongemisch versorgt wird,
d) anschließend wird zusätzliches Fluid unter Druck dem Zylinder (C) und dem Kolben (26) entgegen der durch die Feder (28) ausgeübten Kraft zugeführt, so daß die Ausgleichsmasse (25a) und der exzentrische Bereich (18a, 19a) relativ zueinander in eine Position bewegt werden, die weiter von der Position mit 180° Umfangsopposition entfernt ist, in der die erzeugte verdichtende Vibration von größerer Intensität während eines zweiten Abschnittes der Zeitspanne ist als während des ersten Abschnittes der Zeitspanne, und wobei während des zweiten Bereiches der Zeitspanne eine abschließende Verdichtung des der Formvertiefung zugeführten Betongemisches vorgenommen wird und hierdurch ein Formprodukt erzeugt wird,
e) und hiernach wird das dem Zylinder (C) und dem Kolben (26) zugeführte Fluid entfernt und hierdurch die Ausgleichsmasse (25a) in eine Position mit 180° Umfangsopposition zurückgeführt, so daß die erzeugte Vibration im wesentlichen gleich Null ist, wobei das Formprodukt aus dem Formgehäuse (10) während eines dritten Bereiches der vorgegebenen Zeitspanne des Zyklus abgezogen wird.
a) un châssis vibrant (13) muni d'une caisse de moulage (10) incorporant des cavités de moulage pour un mélange de béton qu'il s'agit de densifier dans les cavités,
b) au moins un arbre (S) provoquant les vibrations monté sur le châssis (13) pour transmettre les mouvements de vibration à celui-ci,
c) des paliers (14) sur le châssis (13) pour le montage des extrémités de l'arbre,
d) des moyens d'entraînement (16) raccordés à l'arbre (S) pour entraîner l'arbre (S) en rotation continue,
e) l'arbre (S) comprenant des tronçons d'extrémité (18, 19) opposés munis de portions (18a, 19a) circonférentiellement fixes excentriques par rapport à l'axe de rotation de l'arbre (S) et une masse d'équilibrage mobile circonférentiellement (25a) pour le mouvement entre une première position circonférentielle dans laquelle la masse d'équilibrage (25a) équilibre sensiblement la force centrifuge impartie excentriquement par les portions excentriques (18a, 19a) des tronçons d'extrémité (18, 19) pour produire un niveau de vibration nul et une seconde position circonférentielle dans laquelle est produite la vibration de densification, la masse d'équilibrage (25a) dans la première position étant sensiblement à 180° opposée aux portions excentriques (18a, 19a) de ces tronçons d'extrémité (18, 19),
caractérisé par les particularités suivantes :f) la masse d'équilibrage (25a) est montée pour la rotation sur les tronçons d'extrémité (18, 19),
g) un évidement a été pratiqué sur l'un des tronçons d'extrémité (18, 19) pour le vérin à piston (C) muni de son piston (26),
h) des moyens (30, 31, 32, 33) sont prévus pour la liaison entre eux du piston (26) et de la masse d'équilibrage (25a) pour produire le mouvement rotatoire de la masse d'équilibrage (25a) par rapport aux tronçons d'extrémité (18, 19) avec le mouvement axial du piston (26) dans le vérin pour déplacer la masse d'équilibrage (25a) à partir de la première position d'équilibrage relativement aux portions excentriques (18a, 19a) en direction d'une position circonférentielle décalée ou excentrée,
i) des moyens de ressort (28) de calibrage prédéterminés sont prévus pour opposer un mouvement axial du piston (26) et ils sont aptes à déplacer le piston (26) dans une direction opposée pour rétablir la masse d'équilibrage (25a) et de piston (26) lorsque la pression sur le piston (26) est libérée,
k) des moyens d'alimentation de pression de fluide (34, 35, 36, 37, 38) sont prévus pour amener le fluide à une pression prédéterminée sur une extrémité du piston (26) en opposition aux moyens de ressort (28) pour commander la position axiale du piston (26) et par conséquent la position circonférentielle de la masse d'équilibrage (25a) par rapport aux portions excentriques (18a, 19a) des tronçons d'extrémité (18, 19).
- un châssis vibratoire (13) avec un caisson de moule (10) incorporant au moins une cavité de moulage pour un mélange de béton devant être densifié dans la cavité,
- au moins un arbre de vibration (S) monté sur le châssis (13) pour transmettre les mouvements de vibration à celui-ci,
- des paliers (14) sur l'arbre (13) pour loger les extrémités de l'ensemble d'arbre,
- un entraînement (16) raccordé à l'arbre (S) pour entraîner l'arbre en rotation continue,
- l'arbre (S) comportant une portion fixe circonférentiellement (18a, 19a) excentrique à l'axe de rotation de l'arbre et une masse d'équilibrage mobile circonférentiellement (25a) montée pour la rotation relative avec la première portion excentrique (18a, 19a) sur l'arbre (S) entre les positions circonférentielles dont une première de masse d'équilibrage (25a) équilibre sensiblement la force centrifuge transmise excentriquement par la portion excentrique (18a, 19a) pour produire un niveau de vibration zéro et dans une seconde position de laquelle est produite la vibration de densification, cette masse d'équilibrage (25a) dans la première position étant sensiblement à 180° opposée à la portion excentrique (18a, 19a),
- l'arbre (S) comportant un vérin (C) avec un piston (26) dont l'un est mobile axialement par rapport à l'autre,
- des moyens reliant entre eux l'un du vérin (C) et piston (26) mobile axialement avec la masse d'équilibrage (25a) pour produire le mouvement rotatif de la masse d'équilibrage (25a) dans une direction circonférentielle par rapport à la portion excentrique (18a, 19a) pour déplacer la masse d'équilibrage (25a) à partir d'une position d'équilibrage par rapport à la portion excentrique (18a, 19a) en direction d'une position circonférentielle excentrée,
- un ressort (28) de calibrage prédéterminé s'opposant au mouvement axial de l'un ou l'autre du piston (26) et vérin (C) mobile et opérant pour le déplacer dans une direction opposée pour rétablir la masse d'équilibrage (25a),
- et des moyens d'alimentation de pression de fluide (38) pour alimenter le fluide à une pression prédéterminée au vérin (C) en opposition au ressort (28) pour commander la position axiale de l'un ou l'autre du piston (26) et vérin (C) mobile et par conséquent la position circonférentielle de la masse d'équilibrage (25a) par rapport à la portion excentrique (18a, 19a),
le procédé étant caractérisé par les étapes suivantes :a) alimentation du mélange de béton dans la cavité de moulage pour la densification pendant une durée de cycle prédéterminée,
b) entraînement en continu de l'arbre (S) à une vitesse prédéterminée,
c) introduction cycliquement pendant une durée prédéterminée successivement de fluide à une pression variable prédéterminée au vérin (C) et au piston (26) en opposition à la force exercée par le ressort (28) pour déplacer de façon relative la masse d'équilibrage (25a) et la portion excentrique (18a, 19a) à partir de sensiblement une position de 180° en opposition circonférentielle dans laquelle la vibration produite est sensiblement zéro jusqu'à une position de production de vibration sensible en dehors de l'équilibre centrifuge sensible pour produire la vibration de densification ayant une intensité pendant une première portion de temps prédéterminée où la cavité de moule est amenée avec le mélange de béton à mouler,
d) après quoi, introduction de fluide supplémentaire sous pression au vérin (C) et piston (26) en opposition à la force exercée par le ressort (28) pour déplacer relativement la masse d'équilibrage (25a) et la portion excentrique (18a, 19a) sur une position davantage éloignée de la position de l'opposition circonférentielle à 180° dans laquelle est produite la vibration de densification de plus grande intensité pendant une seconde portion de temps et au cours de laquelle seconde portion de temps une densification finale du mélange de béton amené dans la cavité de moule se produit pour réaliser un produit moulé,
e) puis extraction du fluide introduit dans le vérin (C) et piston (26) pour rétablir la masse d'équilibrage (25a) sur une position de 180° en opposition circonférentielle de telle sorte que la vibration produite soit sensiblement égale à zéro et le démoulage du produit moulé à partir du caisson de moulage (10) pendant une troisième portion de temps prédéterminée du cycle.