DE3728714A1 - Device for monitoring the function of a high-pressure metering/spraying device - Google Patents

Abstract

The invention relates to a device for monitoring the function of an intermittently operating high-pressure metering/spraying device for spraying a fluid, in particular a polishing paste, which device comprises a housing with a reservoir for receiving and dispensing the fluid, a spring-loaded, adjustable-stroke compressed-air piston/cylinder device with a plunger which can be moved into the reservoir, a valve device which seals the reservoir with respect to a spray nozzle and is operated by the pressure in the reservoir and a low-pressure line which leads from an external collection vessel to the reservoir and has a non-return valve. In this arrangement, a. the reservoir (10) is connected, by pressure-transmitting means (15), to a pressure sensor (19) which has a control circuit and whose pressure signals can be transmitted to an evaluation and display device (20), and b. the compressed-air piston/cylinder device has at least one end-position sensor (21) which can be actuated by the compressed-air piston (5), is connected to a control circuit and whose end-position signals can be transmitted to an evaluation and display device (20). In the low-pressure line or supply line (18) and/or in the reservoir, there is also arranged a fluid-level measurement device (27) whose fluid-level measurement signals can be transmitted to a control unit. The pressure signals, the end-position signals and the fluid-level measurement signals [lacuna] to a common evaluation and display device for ... Original abstract incomplete. <IMAGE>

Description

The invention relates to a device for monitoring the function of a intermittently working high-pressure metering spray device for Spraying out a fluid, in particular a polishing paste, the one Housing with a storage chamber for receiving and dispensing the fluid, a spring-loaded, stroke-adjustable compressed air piston-cylinder-on direction with a plunger that can be moved into the pantry, one that Storage chamber opposite a spray nozzle and closed by pressure in the pantry controlled valve device and one by one outer collecting container with low pressure line leading to the pantry has a check valve.

For surface finishing of a wide variety of workpieces Grinding and polishing machines used, which with brush and Polishing discs are equipped. During operation, the Working surfaces of the brush and polishing discs intermittently a certain paste can be supplied by high pressure spray devices is applied in a metered amount. The high pressure is necessary to apply the paste, because the at high speed rotating tools by the centrifugal forces around an air Build up padding that is penetrated by the paste to be applied must, such that the adhesive forces when hitting the Tool surface can have an immediate impact.

There are already various types of high-pressure sprayers known who perform these tasks, for example from DE-PS 32 02 189 and DE-PS 36 21 947.

An interruption or irregular supply to the grinding and Polishing machines with the necessary paste will damage the Tools and the workpieces to be machined, so that this considerable damage can occur, especially if a faulty function is only discovered at a late point in time.  

In the case of smaller systems, monitoring has so far been carried out by a knowledgeable person, who through ongoing control observations Malfunctions are roughly determined, for example by changing the acoustic environment of the system. For large plants and production lines Function monitoring of this kind is neither justifiable nor economical and often no longer feasible.

If the high-pressure sprayers work reliably, too errors that occur cannot be avoided, for example if the end of the life of certain functional elements by natural Wear is reached, the paste supply due to contamination or air shunts in the supply lines is disturbed Check valve fails, seals fail or the like.

The invention is therefore based on the object of a device for automatic monitoring of the function of a high pressure metering spray propose a device with the help of which all vital Functional elements during operation and operational readiness of the monitoring elements themselves and malfunctions right be displayed in time.

The solution to this problem is that at the beginning listed device the pantry by means of pressure-transmitting Means connected to a pressure sensor having a control circuit is, the pressure signals of an evaluation device can be supplied, and that the compressed air piston-cylinder device at least one of Compressed air pistons operable and connected to a control circuit End position sensor, the end position signals of the evaluation device are feedable.

Part of the task can already be solved in this way perform that in the low pressure line and / or in the pantry  a fluid level measuring device is arranged, the fluid level measuring signals can be fed to a control unit.

Maximum monitoring of the functions and a concrete determination the error or the defective elements can be combined perform the solution features listed above, in which the pressure signals, the end position signals and the fluid level measurement signals of a ge feed common evaluation device for evaluation and error display are cash.

The air piston cylinder device is by means of a through Timed relay controlled solenoid valve, which does the work clock-defining time signal in an advantageous manner the Control circuits of the pressure and end position sensor acted on such that the pressure and end position measurements can be queried during the work cycle are.

In a further development of the invention, the control circuits of the pressure and End position sensor signal storage devices on which of the Time signal determining the work cycle can be activated and upon completion of the Work cycle deleted when signal (no error occurred) and does not return if there is no signal (presence of an error) are set, so that the operability of the printing and End position sensors can be checked after each work cycle. This will ensures that the display of an error is not caused by the error function of a sensor takes place.

According to an advantageous embodiment of the invention, the front Council chamber connected to the pressure sensor by means of a hole, such that that the pressure changes in the pantry by that in the bore located fluid can be transmitted to the pressure sensor. This gives easy installation of the pressure sensor and also maintenance-free and transmission-safe coupling to the print medium.  

The pressure sensor gives a particularly advantageous and operational safe embodiment when a predetermined pressure is exceeded levels a switching signal.

In a development of the invention, at least one end position sensor is a Sensor designed to determine a defined ram position, the at Reaching an end position of the compressed air cylinder by this can be actuated.

In one embodiment, the fluid level measuring device has the Invention two in one measuring section at a defined distance from each other in the low pressure line or the pantry arranged and electrically insulated electrodes, which with a electrical voltage, preferably an AC voltage are beatable.

The invention is illustrated in the drawings Embodiments explained in more detail. Here shows

Figure 1 is a schematic representation of a high-pressure metering spray device in longitudinal section.

Fig. 2 is a block diagram for the description of the operation of the pressure and limit sensors;

Fig. 3 is a schematic representation of the fluid level measuring device in longitudinal section, and

Fig. 4 is a block diagram of the fluid level measuring device.

Fig. 1 shows a schematic representation of a high-pressure dosing spraying device, consisting of a housing 1 having a nozzle 2 and an associated Ventileinrichtugn. 3 Within the housing 1 there is a pneumatic drive with an axially movable in an air pressure chamber 4 air-pressure piston 5 and a prestressed return spring 6, which is designed as a helical compression spring and pressure piston is supported in a spring chamber 8 against an inner housing ring area 7 and the air. 5 A plunger 9 is rigidly connected to the air pressure piston 5 , which extends in its axial movement into the storage chamber 10 and whose head 11 extends in the retracted state to the entrance of the valve device 3 .

Arranged in the storage chamber 10 is a sleeve 12 for reducing the dead space, which is provided with bores 13 for supplying the fluid and with a bore 14 for connection to a housing bore 15 . The bore 13 establishes the connection to a material inflow pipe 16 , at the input of which there is a check valve 17 with a supply feed line 18 . The bore 15 in the housing 1 forms the pressure-transmitting connection to the pressure sensor 19 , the pressure signal of which is fed to an evaluation device 20 .

In its extended position, the air pressure piston 5 contacts an end position sensor 21 , which is located in the housing bore 22 and which also supplies the end position signals to the evaluation device 20 shown schematically.

The evaluation device 20 is acted upon by a clock signal from the time relay 23 , which simultaneously controls a solenoid valve 24 . The solenoid valve 24 controls the compressed air supply to the compressed air connection 25 from a compressed air source, not shown. As a result, the sequence of movements of the piston 5 and thus the entire working cycle of the spraying device is controlled.

To the supply line 18 a shown in Fig. 3 the hose adapter 26 is connected, which is designed as a measuring section for the fluid level sensing means 27, and which on the basis of Fig. 3 will be described in more detail later.

FIG. 2 shows a block diagram for describing the functional sequence of the evaluation device 20 for the pressure sensor 19 and the end position sensor 21 .

Thereafter, the sequence of the monitoring process of the pressure in the storage chamber 10 and the sequence of movements of the air pressure piston 5 , which is described with reference to FIGS. 1 and 2, is as follows.

The pressure in the storage chamber 10 and the end position of the air pressure piston 5 and thus of the plunger 9 are only queried during the stroke cycle.

• 1. The clock signal 30 emanating from the time relay 23 , which controls the entire operating cycle of the device, acts on the solenoid valve 24 , whereby compressed air flows into the air pressure chamber 4 and axially drives the air pressure piston 5 and thus the plunger 9 .
• 2. The plunger 9 increases the pressure in the storage chamber 11 until the pressure specified in the valve device 3 is reached and the valve opens.
• The clock signal 30 emanating from the time relay 23 and determining the operating cycle is simultaneously fed to the evaluation device 20 , whereby intermediate stores are activated in the control circuits of the pressure and end position sensors, as represented by 31 and 32 in FIG. 2. If a signal 33 or 34 occurs when the work cycle is completed, ie if there is no error, the intermediate memories are deleted, as represented by 35 and 36 in the course of time.
• If there is no signal, ie if there is an error, the buffers are not reset s. see 37 and 38 . This circuit sequence checks the functionality of the pressure sensor and regardless of the end position sensor after each work cycle.
• If there is an error display of one or both monitoring devices, the respective interference signal is processed ( 39 or 40 ) and displayed ( 41 or 42 ) and counted ( 43 or 44 ) and an error message 45 is issued . In order to avoid false indications, it is expedient to carry out an amplification of the intermittent error signal 47 only in the case of fault messages which occur immediately after one another and then to display this signal 48 and to evaluate it accordingly.
• Numeral 50 in FIG. 2 denotes the drop in signal 30 .
• 3. In the further mechanical process, the plunger 9 displaces the paste from the storage chamber 10 as soon as the pressure built up becomes greater than the predetermined and adjusted pressure in the valve device 3 . This process continues until the air pressure piston 5 is at its front stop. When the air pressure piston 5 reaches this position, it actuates the limit switch 21 , which gives a corresponding signal.
• 4. The pressure build-up in the storage chamber 10 is fed via the bore 15 to the pressure sensor 19 , which generates corresponding pressure signals and sends them to the evaluation device 20 . After the ejection process, the pressure in the storage chamber 10 drops and the pressure sensor 19 switches back to its starting position.
• 5. The solenoid valve is closed, and the return spring 6 returns the air pressure piston 5 and the plunger 9 to the starting position and the limit switch 21 switches back to its starting position.
• 6. If a rear stop sensor is provided, it is generated this a signal when the air piston turns its rear off gear position has reached.
• 7. When another time signal 23 arrives, the process described is repeated.

In order to avoid malfunctions, as already explained above not clearing the signal immediately, but only after another malfunction is displayed. This number can be any increase. This means that there are always two consecutive Clear signals must be absent to trigger an alarm during the However, error appears immediately.

With a permanently present delete signal, e.g. B. in the case of a defective one Pressure or stop switch, an alarm is therefore also triggered, so that the sensors are monitored.

The alarm signal either goes out automatically after the Continuation of the function, or after disconnection from the mains.

Sequence of the signals

• 1. The electrical signal to open the solenoid valve is present its relay on.
• 2. The buffer belonging to the individual sensors, which is designed, for example, as a bistable multivibrator, is activated.
• 3. The signal from the pressure sensor and the end position sensor is present when the pressure in the storage chamber and thus in the valve device 3 exceeds a preselected value, so that a switching function takes place. This pressure is selected so high that there is no switching through when the pressure in the storage chamber is increased.
• The switching point is also lower than the spray pressure, hence small fluctuations in pressure over the operating time lead to a malfunction.
• 4. The presence of the individual sensor signals leads to a reset, ie deletion of the respective buffer ( 35 or 36 in FIG. 2). Each deleted buffer is immediately prepared for processing a new input signal from the electrical time relay 23 .
• 5. As long as the electrical signal of the clock or time relay 23 is present, no fault is released for further processing.
• 6. After the clock signal has been removed, if there is no sensor signal - because only now it is absolutely certain that a sensor should have worked when it is fully functional - the path to processing the error message is clear (see FIGS. 37 and 38 in FIG. 2).
• Is the signal from a sensor before the activation of the Buffer, so is the path to error processing Approved. This happens when one of the sensors "stuck" in the connected process, so that a There is a sensor defect.
• 7. A fault message is used for two functions. So the respective fault is immediately displayed visually, and further the fault message is counted in a counter.
• This counter has the task of forwarding everyone instantly Prevent malfunction at the central malfunction detector.  
• Is z. B. set a two-time absence of the signal, so this means that the signal is missing twice in a row must be so that a fault message is issued. When deleting the This procedure is analogous to fault reporting.
• The advantage of this measure is the buffering of the sensor signals so that not every "random" evoked sensor fault leads to a fault message.
• 8. After passing on the malfunctions from at least one intermediate counter, a fault message is generated.
• 9. This fault message is converted into an intermittent signal (see 45 and 46 ) by a clock generator.
• 10. This signal is amplified ( 47 ).
• 11. An optical and / or acoustic warning signal indicates the malfunction of the entire system ( 48 ).

The presence of the grinding or polishing agent, which has a pasty viscosity, is continuously monitored with the aid of the fluid level measuring device 26 . There are two different ways of monitoring, namely:

• 1. the monitoring of the filling quantity or the fluid in the storage or collecting container 10 , and
• 2. the monitoring of the fluid in the supply line 18 .

Both options can be carried out advantageously.  

The operation of the fluid level measuring device is described in more detail with reference to FIGS . 1, 3 and 4.

The basis of the fluid level measurement method is the measurement of the conductivity of the fluid to be monitored. If there is a fluid between the two electrodes 28 and 29 in the measuring section 26 , an electric current flows which is greater than the switching level. If the fluid is lost, the current drops below the switching level. This is processed into a warning signal by means of an electronic circuit.

When monitoring non-electrically conductive media, the Change in resistance of electronic components as a switching signal to be pulled. The medium takes over the heat dissipation of the electrical component. Depending on the application, the deviation can now be queried continuously or clocked from the setpoint.

The circuit board (not shown) with the electronic components is accommodated in the housing of the fluid level measuring device 27 . A lamp with a 24 V operating voltage is installed in the housing and there is an acoustic signal generator 49 on the cover.

The circuit is designed so that in the absence of monitoring fluid an intermittent signal is emitted. The The circuit board used to hold the circuit has two separate ones Outputs carried out with different voltages, for one Lamp and for an acoustic signal. Particular emphasis was placed on one simple addition of the monitoring unit to existing systems placed. To ensure the highest level of connection and maintenance friendliness achieve, all components of the system are one unit summarized, d. H. Sensor, circuit, warning lamp and acoustic Detector.  

The poles 28 and 29 can consist of two line spacers. They are each equipped with a sensor pole and arranged in a non-electrically conductive supply line or measuring section 26 .

The sensor or the electrode 29 consists of an intermediate piece in the supply line with a sensor pole. The second pole 28 is also attached in the measuring section 26 (see FIG. 3) or in the storage chamber 10 .

Monitoring of the medium in the storage chamber 10 is also possible with two sensor poles. The poles or electrodes can be inserted into the container on a rod or on two rods. It is also possible to attach the poles directly to the container, to a rod in the container, or to a pole on the container.

As can be seen from FIG. 4, the sensor 28 is connected to the voltage 51 and to the comparator 52 , which in turn is connected to the reference source 53 . The difference signal originating from the comparator is fed to a clock generator 54 , which is followed by the amplifier 55 , which generates the output signal 56 .

When monitoring a medium using semiconductor components as sensors, it is necessary that the "sensor" and the "reference element" are only a short distance apart. Here, an application is possible both within the supply line 18 and in the pantry.

Claims (9)

1. Device for monitoring the function of an intermittently working high-pressure metering-spraying device for spraying a fluid, in particular a polishing paste, which has a housing with a storage chamber for receiving and dispensing the fluid, a compressed air-piston-cylinder device with one in the storage chamber Slidable plunger, the storage chamber opposite a spray nozzle and ge controlled by the pressure in the storage chamber valve device and a leading from an outer reservoir to the storage chamber low pressure line with a check valve, characterized in that

• a. the storage chamber ( 10 ) is connected by means of pressure-transmitting means ( 15 ) to a pressure sensor ( 19 ) having a control circuit, the pressure signals of which can be fed to an evaluation and display device ( 20 ), and that
• b. the compressed air piston-cylinder device has at least one end position sensor ( 21 ) which can be actuated by the compressed air piston ( 5 ) and is connected to a control circuit, the end position signals of which can be fed to an evaluation and display device ( 20 ).

2. Device for monitoring the function of an intermittently working high-pressure metering-spraying device for spraying a fluid, in particular a polishing paste, which has a housing with a storage chamber for receiving and dispensing the fluid, a compressed air-piston-cylinder device with one in the storage chamber Sliding plunger, a storage chamber opposite a spray nozzle and ge controlled by the pressure in the storage chamber valve device and a leading from an outer reservoir to the storage chamber low pressure line with a check valve, characterized in that in the low pressure or supply line ( 18 ) and / or in the storage chamber a fluid level measuring device ( 27 ) is arranged, the fluid level measuring signals can be fed to a control unit. 3. Apparatus according to claim 1 and 2, characterized in that the Pressure signals, the end position signals and the fluid level measurement signals a common evaluation and display device for errors diagnosis and error display can be fed. 4. Apparatus according to claim 1 or 3, characterized in that the compressed-air piston-cylinder device can be controlled with the aid of a solenoid valve ( 24 ) clocked by a time relay ( 23 ), the time signal determining the working cycle simultaneously controlling the control circuits ( 20 ) of the pressure and end position sensor ( 19 or 21 ), such that the pressure and end position measured values can be queried during the work cycle. 5. Apparatus according to claim 1, 3 or 4, characterized in that the control circuits of the pressure and end position sensor signal memory have facilities which of which the work cycle determining time signal can be activated and upon completion of the Work cycle when signaling (no error occurs) deleted and if there is no signal (there is an error) not be reset, so that the functionality of the Pressure and end position sensors can be checked after each work cycle. 6. The device according to claim 1 or 3 to 5, characterized in that the storage chamber ( 10 ) by means of a bore ( 15 ) is connected to the pressure sensor, such that the pressure changes in the storage chamber ( 10 ) by the fluid in the bore the pressure sensor ( 19 ) can be transmitted. 7. The device according to claim 1 or 3 to 6, characterized in that the pressure sensor ( 19 ) emits a switching signal when a predetermined pressure level is exceeded. 8. The device according to claim 1 or 3 to 7, characterized in that at least one end position sensor ( 21 ) is designed as a sensor for determining a defined plunger position, which can be actuated by this when each end position of the compressed air piston ( 5 ). 9. The device according to claim 2 or one of the preceding claims, characterized in that the fluid level measuring device ( 27 ) two in a measuring section ( 26 ) at a defined distance from one another in the low pressure or supply line ( 18 ) or the storage chamber ( 10 ) arranged and has electrically insulated electrodes ( 28, 29 ) which can be subjected to an electrical voltage.