DE102016003944B4 - Device for quality monitoring on a block molding machine - Google Patents

Abstract

Device for quality monitoring on a block molding machine, which has a frame (1), a mold (11) and a vibrating table (13) which interacts with this mold (11) and oscillates in a vibration direction, and which is provided with a plurality of sensors with a Evaluation unit are connected, with several sensors being fastened in positions transversely to the vibration direction of the vibration table (13), the sensors measuring the relative movement of the vibration table (13) with respect to the frame (1), the sensors in the area of corners of the vibration table (13 ) are arranged, the sensors each determining the local distance between the vibration table (13) and the frame (1), characterized in that the evaluation unit checks whether all the sensors monitoring the vibration plate in their movement have the same amplitude and also a non-phase-shifted movement determine, the sensors ve directly to the frame (1) The sensors are only arranged on a component within the block molding machine, the sensors being fastened to the frame (1) via plastic brackets made of polypropylene with a high level of damping, with a further sensor additionally in the area near the center of the sides or near is arranged to the central center of the vibration table (13) for determining a reference value.

Description

The invention relates to a device for quality monitoring on a block molding machine, according to the preamble of claim 1.

The production of concrete blocks with a block molding machine is known.

Concrete is automatically poured into a mold and then compacted in it. During this compression, for example, air inclusions are driven out by the settlement of the material.

The compaction is usually done by dynamic excitation of the form by means of a vibration, which also increases the density and strength of the concrete.

The compacting of the concrete in a mold can also take place in several stages, with a core concrete being compacted in a first stage and then in a second stage after a facing concrete is also compacted.

The block molding machine has a frame and, for the compression, a vibrating table which is movable relative to the frame and with which the concrete-filled mold is subjected to vibrations on one side, in particular from below, while a punch usually loads from above into the normally horizontal arranged form presses, which is attached to a particular part of the frame forming Auflafrrhmen.

The said punch is supported on a cross yoke, which is connected to a lower yoke via lateral supports, so that these elements together form a frame.

The vibration table, which is usually flat and is arranged horizontally, is then caused to vibrate, the direction of vibration being aligned normal to the extension of the vibration table, that is to say vertically in the usual case.

The table vibrating in this way strikes from below against a production base (e.g. a sheet metal) arranged within the frame and thus against the concrete-filled form resting on this production base and thus leads to the desired compaction of the concrete in this form.

In order to be able to monitor the quality of corresponding products manufactured with such a block molding machine, M. Walter proposed a relatively complex system in the article “Intelligent monitoring for quality assurance”, BFT 11/2007. In this system, z. B. determined the weight of intended for filling forms or molded parts by means of weighing devices. In addition, after the vibration step, the height of the stones produced is recorded by means of one or more laser sensors.

Furthermore, force, frequency, time and distance measurements are also carried out on a large number of components of the production machine during the production step, including in particular the stamp for the load, the load frame, the vibration table and the entire frame.

Furthermore, sensors can also be provided on corresponding load springs as well as on rubber springs for table mounting, on knocking strips that are firmly attached to the frame, etc.

The values determined by these multiple sensors are then transmitted to a central evaluation unit to which the sensors are connected. In this evaluation unit, the data are processed using various calculation algorithms with the addition of system data stored in files with regard to concrete densities and / or specific system data and then output to log files for archiving and / or to monitors etc. for visual display and evaluation.

But now it is the case that the production of concrete parts is an extremely unfavorable environment for the acquisition of measured values, because the required sensors are exposed to a considerable extent not only to vibrations but also to contamination and mechanically aggressive media.

In the case of the system described above, a considerable number of interference-sensitive sensors must be taken into account in this regard, which stand in the way of an operationally reliable design. For example, the laser sensors provided for height measurement are extremely sensitive to dirt and therefore require a lot of maintenance, so that they seem suitable for a laboratory setup, but only to a limited extent for tough use in industrial production. Corresponding laser sensors are relatively expensive.

The document is still from the prior art DE 10 2006 047 543 A1 known. In this document, a block molding machine is shown which is provided with actuators. The actuators can cause a mold frame to vibrate, the mold frame being connected to a vibrating table via hydraulic cylinders. In these actuators sensors can be provided which the by the actuator Measure the movement caused and thus enable the actuators to be controlled.

Furthermore, the document DE 297 12 242 U1 known. This document shows an unbalance vibrator for compacting concrete elements. Sensors can be provided which detect vibration values of the vibrating table and feed them to a control device.

Furthermore, the document is DE 195 42 868 A1 known, which shows a monitoring device for a manufacturing process of concrete moldings. Vibrators are used to generate vibrations in a vibrating table. Accelerometers are arranged on the vibrators, which record the vibrating forces applied to the vibrating table and feed them to an evaluation unit.

Finally, the pamphlet is DE 3837686 A1 known. This document shows a vibrating machine for forming concrete masses. An oscillating frame contained therein is supported by suspension springs. The parameters stiffness and damping in one or more suspension springs are determined using pressure sensors or speed sensors.

From this aspect, the task of the invention is to reduce the number of corresponding sensors to a minimum in order to increase the operational reliability and at the same time to reduce the costs.

The object is achieved by a device for quality monitoring on a block molding machine according to claim 1.

According to the invention it is therefore proposed, instead of providing sensors on a wide variety of components and assemblies of the block molding machine, to attach a plurality of sensors in positions spaced apart transversely to the vibration direction of the vibration table, which detect the movement of the vibration table relative to the frame.

The invention is based on the knowledge that a uniform vibration of the vibrating table over its dimensions with the same vibration amplitude and with the same phase position is decisive for a uniform product quality.

While a production that leads to a uniform, high quality of the products produced is characterized in particular by an amplitude that is uniform over the dimensions of the vibration plate, machine defects that reduce the product quality, such as faulty, knocked out, cracked or otherwise worn out, or simple only aged rubber buffers or blow bars etc. with a changed degree of hardness, as well as uneven filling of molds due to changed or changing local changes in the vibration behavior of the vibration table are noticeable, as they virtually cause the vibration plate to wobble.

Such a wobbling of the vibrating table can be reliably determined by evaluating the data that are supplied by sensors that are spaced apart from one another transversely to the direction of vibration, either on the frame or on the vibrating table.

It is essential to the invention that the corresponding sensors are to be attached to only one component within the block-making machine and that such attachment is also possible, if necessary, in devices that are already on the market. This means that machines that are already in operation can also be retrofitted.

In contrast to the prior art discussed above, it can also be seen that a vibrating table only moves over relatively short distances. This means that the connection of sensors, which are attached to the frame or the vibration table in particular, is much easier to implement than, for example, the connection of sensors to the loading frame or to the loading ram, which are moved over relatively long distances between individual production cycles. Relatively long cable connections bridging these distances would have to be provided for these, but these can lead to problems again within the machine.

According to the invention, at least two of the sensors provided are designed as displacement sensors with which the relative movement between the vibrating table and the frame can be detected. Displacement sensors have the advantage that the data they provide enable quick and easy evaluation. The measured path is measured between the frame and the vibrating table so that short measuring distances are possible that are only less susceptible to interference.

But it is also possible to design the sensors as acceleration sensors and to attach them to the vibrating table. A somewhat higher computational effort may then be necessary here.

In principle, a combination of displacement and acceleration sensors is also possible.

According to the invention, the sensors are attached to the frame by means of plastic brackets. Suitable plastics such as polypropylene are not only relatively wear and chemical resistant, but also have a high Self-damping, which has a positive effect on the generation of the measurement signals, which are therefore less subject to interference.

It should also be mentioned that a device as described here can be implemented both with amplitude-modulated vibration exciters and with frequency-modulated vibration exciters, which are preferably each attached to the vibration table.

With a device according to the invention, an operator can intervene with regard to a corresponding repair or readjustment of a machine if not only are the amplitudes of two sensors provided on the vibration table different, but also if they do not vibrate in phase with one another. Such a phase shift is namely an essential indicator for the tumbling of the vibrating table, which is to be prevented according to the inventors' knowledge.

According to the invention, the sensors are arranged in the area of the corners of the vibrating table. The frame as well as the vibrating table are essentially considered to be rigid.

In the area of the mentioned corners of the vibration table, the data measured here are particularly meaningful due to the boundary conditions that determine the damping there.

The area near the center of the sides or near the central center of the vibrating table has proven to be a further location for a favorable arrangement of a sensor, since a good reference value can be determined at these positions against which the values are assessed with regard to a wobbling of the vibrating table which can be determined at the corners of the vibrating table.

With a device of the type described here, stone production can also be significantly simplified: While previously the idle amplitude of a vibration table was essentially determined and then its permissible deviation was only determined product-specifically by means of several production cycles, there is now the possibility of measuring the amplitude and one possibly existing phase shift between different measuring points on the vibration table during the first production cycle of a block molding machine with a specific product to be able to draw conclusions about the quality of the product produced.

• 1 die schematische Ansicht des Produktionselements einer Steinformmaschine;
• 2 die Prinzipskizze eines taumelnden Vibrationstisches

Quality assurance for the products to be manufactured can thus be considerably simplified and, in particular, starting up a machine after a changeover to another product can be carried out with considerably fewer rejects. Further advantages and features of the invention emerge from the following description of an exemplary embodiment. It shows

• 1 the schematic view of the production element of a block molding machine;
• 2 the basic sketch of a tumbling vibrating table

In the 1 you can see the view of a production element of a block molding machine.

This has a frame 1 on. This consists of two lateral supports 2 at their lower end with a sub-yoke belonging to the frame 3 are connected and at their upper end with a cross yoke 4th . At the cross yoke 4th is a loading frame 5 attached to the with a stamp cylinder 6th along the supports 2 is to be moved downwards, this movement possibly via braking swords 7th can be braked. On the loading frame 5 is a mold top 8th with the interposition of a locking plate 9 mounted, with elastomer springs if necessary 10 be used.

By means of the punch cylinder 6th becomes the upper part of the mold 8th in a form filled with concrete 11 pressed that on a production sheet 12th stands.

By activating a vibrating table 13th the one below the production document 12th within the frame 1 is arranged as a substantially flat component in the horizontal direction, is from below against the production base 12th and thus against the form 11 beaten, which leads to a desired compaction of the concrete in the form. The vibrating table 13th is about elastomer elements 14th in brackets 15th guided.

Basically there is also a vibration of the upper part of the mold 8th possible. But this is not taken into account here.

It has now been found that, in particular, the vibration table vibrates evenly over its extension 13th is essential for the production of good quality of manufactured products.

Does it come like in the 2 the production document is shown over the essentially horizontal extension of the vibration table to different amplitudes and / or phase positions 12th not evenly everywhere (as in the 2a shown) but unevenly (as in the 2 B shown) from below with an impulse from the vibrating table 13th acted upon, causing the compaction of in a form on the production base 12th existing concrete for stone blanks turns out differently. In this way, stones of varying quality are produced in an undesirable manner.

Corresponding inclinations of the vibration table 13th as in the 2 B are shown result from faulty, chipped, cracked or even just aged elastomer elements 14th . Such inclinations cause movement of the vibrating table to be seen as wobbling 13th . In order to recognize this automatically, sensors are attached that monitor the relative movement of the vibrating table 13th opposite the frame 1 measure up. Such sensors can be used as displacement sensors in particular in the area of the corners of the vibrating table 13th near the supports 2 to be appropriate.

These displacement sensors are in the 1 at a distance from one another in the plane of the drawing essentially in the horizontal direction, since the vibration table is moved up and down essentially in the vertical direction when it vibrates.

The sensors are on the lower yoke 3 or attached to a subframe, not shown here, connected to it - that is, directly or indirectly with the frame 1 connected - and thus determine the local distance of the vibrating table 13th towards this.

Alternatively, it is also possible to use these sensors on the vibration table 13th to attach and then the distance to the lower yoke 3 to investigate. This is constructive but more complex.

When attaching sensors to the vibration table 13th Acceleration sensors can also be provided.

In principle, the data determined by the sensors are sent to an evaluation unit that is not specified here. This is used to check whether all the sensors monitoring the vibration plate in terms of their movement determine the same amplitude and also not phase-shifted movement. If differences arise here, the vibration table will wobble undesirably 13th are present and can take appropriate measures, for example checking and replacing elastomer elements.

The invention thus provides the possibility of intervening in good time at the first signs of changing production cycles and thus achieving a consistently high product quality.

List of reference symbols

1

frame

2

Support

3

Subjugation

4th

Cross yoke

5

Loading frame

6th

Stamp cylinder

7th

Brake swords

8th

Mold top

9

Locking plate

10

Elastomer springs

11

shape

12th

Production document

13th

Vibrating table

14th

Elastomer elements

15th

Brackets

Claims (1)

Device for quality monitoring on a block molding machine, which has a frame (1), a mold (11) and a vibrating table (13) which interacts with this mold (11) and oscillates in a vibration direction, and which is provided with several sensors which are equipped with a Evaluation unit are connected, with several sensors being fastened in positions transversely to the vibration direction of the vibration table (13), the sensors measuring the relative movement of the vibration table (13) with respect to the frame (1), with the sensors in the area of corners of the vibration table (13 ) are arranged, the sensors each determining the local distance between the vibration table (13) and the frame (1), characterized in that the evaluation unit checks whether all the sensors monitoring the vibration plate in their movement have the same amplitude and also a non-phase shifted one Determine movement, whereby the sensors are directly connected to the frame (1 ) are connected, the sensors are only arranged on one component within the block molding machine, the sensors being attached to the frame (1) via plastic brackets made of polypropylene with high damping, with another sensor additionally in the area near the center of the sides or else is arranged close to the central center of the vibration table (13) for determining a reference value.

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