DE1477955A1 - Sandblasting blower - Google Patents

Description

PATENTAN WJfM B _: DR. ING. KARL BOEHMERT DIPL-ING. ALBERT BOEHMERT

28 BREMEN · FELDSTRASSE 24 · * TEL. (0421) 491760, 442551

File number:

77 955-6

Abrasive Developments Ltd.

Postal checking account: Hamburg 126083 Bank account: Bremer Bank, Bremen, Klo, 1001449 My sign:

3-79

28 Bremen, October 2, 1968

Abrasive Developments Limited, Henley-in-Arden, County Warwick (Great Britain)

Sandblasting blower

The invention relates to a sandblasting blower with a pressurized gas source, an abrasive container, a blow-out nozzle for a gas-abrasive mixture connected to these via a conveying line, devices for vibration of the abrasive container and Devices for changing the vibration amplitude

It is already a device for generating a gas stream loaded with a grinding or abrasive agent known, in which the abrasive container is supported by means of leaf springs on a base and

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by an electromagnet attached to the base, which is connected to a magnet armature connected to the container cooperates, is set in vibration, the frequency of which is supplied to the electromagnet AC frequency corresponds to «The vibration amplitude of the container by changing the air gap between the armature and the core of the Electromagnets are changed, while the frequency of vibration invariably depends on the frequency of the one used Alternating current depends «It is therefore not possible with the known device to determine the frequency of the Container constantly the basic resonance frequency, which is dependent on the fill level to adapt

The abrasive leaving the container passes from the container into a conveying line in which it is in

is passed on to a stream of pressurized gas and finally emerges from a nozzle.

It is also known an abrasive blower, the Abrasive container with a non-adjustable, pneumatically or electrically working sighting device connected is. This blower cannot respond to the basic resonance, which depends on the level of the container.

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frequency driven and therefore requires considerable forces to excite the vibrations »

The object of the present invention is to provide a sandblasting blower with an easy and precise rule = able to create a supply of the abrasive, in which the vibrations required to excite the container Forces and. thus the necessary to generate vibrations Services are as low as possible »

This task is invented by one at the free End of a cantilevered support arm arranged abrasive medium container, one on this or on the free End of the support arm arranged electric motor with a characteristic opposite to the abandoned one Load changing speed as well as one driven by the motor, that of the support arm, abrasive container and ifcotor existing system approximately its basic resonance frequency corresponding vibration-emitting centrifugal mass released

The motor can be a main or a series electric motor on whose motor shaft the flywheel can be arranged

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Preferably, the control device is one of the engine to overcome the inertia of the centrifugal mass "when starting, increased energy supplying starter device on, which can be a capacitor that is charged when power is supplied to the engine and when the Motor provides additional energy.

The control device can also have a variable resistor that is fully switched into the motor circuit when the engine is started have, one end of which after a predetermined period of time after power has been supplied to the motor with the variable tapping of the control resistor is short-circuited especially the current drawn from the grid when starting is limited «.

In the following part of the description, an exemplary embodiment of the subject matter of the invention is described with reference to drawings
Show it:

Fig. 1 is a partially in section and partially

broken away side view of a sandblasting blower according to the invention;

2 shows a longitudinal section through a blower nozzle of the sandblasting fan;

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3 is a diagram of the pneumatic flow circuit of the machine; and

Fig. 4 is a circuit diagram of the control device for the machine.

As can be seen from Fig. 1, the machine is one Base plate IQ, on one of which © ade a fixed Column 11 is attached. The column is stiffened in its position by a hip 12 with the upper one At the end of the column 11 a beam IJ is screwed, with one end of the beam is anchored between the top of the column and a cover plate 14 and by screws 15 is held in position.

On the free end of the beam is a whole with 16 designated container arranged. The container has a cylindrical portion 17, which on his The lower end is screwed to an inverted, frustoconical section 18 at the upper end of the frustoconical Section 18 is a perforated metal plate 19 is attached, from the center of a tube 20 after protrudes above, which opens with its lower end in the frustoconical section 18 o The upper The end of the tube 20 is provided with a gauze or wire gauze 21 to prevent abrasives or blown

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sand gets into the pipe 20.

Between the perforated plate 19 and the lower edge of the cylindrical portion 17 is a nylon mesh screen 22 arranged, the edges of which between the covering flanges at the upper end of the frustoconical Section 18 and the lower end of the cylindrical section 17 are clamped, the splash are connected to one another by screws 23.

The upper end of the container is provided with an inlet, which has a spring-loaded closure member 24 which has a substantially bell-like shape. Mn frustoconical housing 25 is with the head plate 26 of the container, with spokes 27 supporting a bearing 28 in the housing 25. A vertical one The rod 29 is slidably arranged in the bearing 28 and its lower end is connected to the locking part 24, The rod 29 is provided with an operating button 30 at its upper end, with a spring 31 between the Bearing 28 and the button 30 is arranged. The plate is provided with a recess around the inlet, in which an O-bing 32 is inserted, which is the upper Seals surface of the closure member 24, as shown in FIG.

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The container is at its lower end with a one T-piece 33 forming the outlet «One side of the T-piece is with a discharge pipe 34 and the other Side of the T-piece connected to a compressed air line 35. The line 35 is fed by a main air line 36, which is at a T-piece 37 in the Compressed air line 35 and another compressed air line 38 divides · The compressed air line 38 opens into the upper part of the container via an angle piece 39 «.

Jw container is mounted a console 40 on which a main power motor 41 is screwed · The motor 41 carries on its shaft 42 an eccentric oscillating weight 43β The motor is controlled by a circuit, which was to be subsequently described * ·

With reference to FIG. 3, the pneumatic The machine's flow circuit described ««! will" The machine has a compressor t |, 4, which Compressed air is discharged into a line 45, which is a dryer 46 happened. Although a compressor forming part of the machine is shown, the machine can also be of a outside the compressed air table are fed, especially if the plant has a number of

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BAD ORiGfNAL

Sandblasting is used from a central Compressed air source are fed.

The air line 45 leads to a branch piece 47, from which in one direction the main compressed air line 56 leading to the container 16 is derived. The discharge line 54 leads via a pneumatically operated valve 48 to a T-piece 49 and opens into an outlet pipe 50 a, which feeds the nozzle designated 51.

Another pipe 52 leads from the connection piece 47 via a pneumatically operated valve 55 to the T-piece 49. Another pipe 54 leads from the connection piece to a pipe connected to lines 56 and y? connected T-piece 55 o The branch line 56 leads to the valve 55 and the branch line 57 to the valve 48. The passage of compressed air through the branch line 56 is controlled by a solenoid valve 58 and the passage of compressed air through the branch line 57 is controlled by a solenoid valve 59

Eb reference is now made to FIG. 2, in which the nozzle designated as a whole by 51 is shown. The nozzle 51 has a body 60 in which the outlet pipe 50 is fastened by means of an internal thread 61. A seal holder 62 is inserted into the end of the body 60.

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ORIGINAL

screws, in which a rubber seal 63 is arranged. ■ FCIN nozzle tube 64 is accommodated with its U a bath in the seal 63 ₁ ^ _w i _r a fixed by means of a Düsenrobrhalters 65 in position. The holder 65 is screwed into a seal holder 62 and, when screwed in, presses the seal 63 together »so that it grips firmly around the nozzle tube 64 ·

Reference is now made to FIG. 4, which shows the Shows control device for the machine. The power for the machine is supplied by the power lines L1 and L2 double-pole main switch S1 supplied »A fuse 66 is in the line L1 and the operating state the machine indicating warning light 67 arranged between the lines L1 and L2 after the main switch S1 has been closed, the machine stops operating controlled by two further foot switches S2 and S3.

A rectifier bridge 67 is arranged between lines L1 and L2 and has output lines 68 and 69 on. A further line 70 is arranged between the lines 68 and 69, in which the foot switch S2 and the winding C1 of an actuating relay R1 is arranged is.

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Furthermore, between the lines 68 and 69 is a Line 71 provided, in v / elcher in series Tapping resistor 72, a controllable resistor 73 and ..a second tapping resistor 74- are arranged The tapping line 75 of the resistor 74 · passes through a Relay contact C1H1 of relay R1, motor A-I and then via a milliammeter 76a back to line 69 A capacitor 76 is arranged between the line 75 and the line 69.

The switch S3 is arranged in a line 77 which extends between the lines L1 and L2 ₉ , this line also containing the solenoid 58S for the solenoid valve 58. Another line 78 between the lines L1 and L2 contains a second contact C2R1 of the relay R1 and also the solenoid 59S of the solenoid valve 59ο A line 79 connected in parallel to the solenoid 59S contains a winding C2 of a time delay _{relay R2 O} A contact C1R2 is arranged between the variable tap 80 of the variable resistor 73, with a line 81 to the junction between the resistors 73 and 74 leads.

The operation of the machine is such that when the double pole switch S1 is closed, current is over

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ORIGINAt

the Gleichriciiterbrucke 67 and further via the conduits 68, 69 flows through the resistors 72, 73 and 74 and the capacitor 76 is charging ₀ If it is now desired au sandblasting a surface, the switch S2 is closed in the line 70, whereby the Eelaiswieklung S1 is excited and thus the contacts C1R1 and C2R1 are closed o As a result of the closing of the contact C1R1, the capacitor 76 discharges via the motor 41, so that increased energy flows to the motor and sets it to rotate. The increased Eneergiezufuhr helps the initial inertia of the Schwinggewiehtes 43 to be overcome en _e Once the capacitor has discharged, the rotor with the voltage from the rectifier bridge 67 via the line 68, the line 71 and the resistors 72, 73 and 74, the line 75, the contact CIR-f, the milliammeter 76a is fed and the current is fed back via the line 69 to the bridge 67 »

Closing contact 02R1 in the line energizes the solenoid of solenoid valve 59 so that pressurized air can flow into branch line 57 to open pneumatic valve 48 and allow blasting sand and pressurized air to pass through discharge line 34 to nozzle $ 1 . Closing the con-

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ORIGINAL

clocked C2R1 also energizes winding 02 of the relay S2 and after a predetermined time the delay relay R2 closes the contact C1R2, whereby the Siphon line 80 is connected to the junction between the resistors 73 and 74, so that changes in the position of the bleed line 80 the dem kotor 41 changed the current supplied by the rectifier bridge 67 * The resistor 72 is set in advance so that it has the maximum current supply to the motor limited ^ while the previously set resistance the minimum current supply to the motor is determined. The maximum and minimum supply are determined according to the requirements the machine selected The Seiais R2 is preferably set so that the contact C1R2 about three seconds is closed later than the relay winding 02 is excited.

The operation of the beam and the container will now be described the swing weight begins to rotate, the free end of the beam is set in essentially vertical oscillations, which with increasing engine speed gain weight. The beam 13 »the container 16 and the motor 4-1 form together with their associated consoles and am

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Beams attached parts a system with a certain resonant frequency o The speed of the motor is set so that the system oscillates at this resonant frequency ₉ The motor and beam are then locked at this state, known as "dynamic coupling", with the motor turning rotates with the speed, with v / elcher the oscillating weight executes the same number of rotations as the beam oscillates. This means that the forces exerted by the electric motor and the oscillating weight try to keep the system in its resonant oscillation state, since the impulses given to the end of the beam are in phase with the oscillations carried out by the beam. It has been found that when this state is reached, small changes in the energy supplied to the motor change the amplitude of the vibrations without causing any appreciable changes in the speed of the motor the vibrations of the container is changed. Once the motor has reached the desired speed, the energy supply can be controlled by adjusting the discharge line 80 on the adjustable resistor 75, the result

can be measured by the milliammeter 76a « 90982A / 0A29

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V; hen the container vibrates at the desired frequency, does the blow sand happen in the cylindrical section 1? the sieve 22 and the perforated plate 19 and gets into the frustoconical section 18. The speed with which the blow sand passes the sieve depends

on the amplitude of the vibrations of the container » The blow sand falls from the frustoconical section 18 into the T-piece 33, with the one emerging from the line 35 Compressed air picks up the blow sand and passes it through the discharge pipe 34, the pneumatic valve 48, the T-piece 49 and the outlet pipe 50 conveyed to the nozzle 51 The material flows through the nozzle tube 64 and is then onto the object to be cleaned or the surface directed.

Since pressurized air is supplied to the sides of the container both above and below the screen, the blowing sand particles fall not against a downward flow of air and therefore do not tend to be electrically charged and to be rejected »Further, the placement of the tube 20 allows breathing between the upper and lower lower portion of the container, thereby reducing the undesirable dampening effect that passes through the sieve the blowing sand, which tries to act as a piston, is caused.

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f -τ ι f Vf VV

When the sandblasting process is finished, the switch S2 is opened, whereby the circuit via the winding of the relay R1 is interrupted and the contacts C1E1 and C2B2 are opened. Thereby, the läotor stopped and the solenoid 59S of the solenoid valve 59 is de-energized, so that the compressed air supply to the pneumatic valve 48 is interrupted and this can close to prevent any further air blast sand know pass through the outlet pipe 50 _o If it is now When it is desired to blow the blowing sand away from the workpiece, switch S3 is closed "thereby energizing solenoid 58S of solenoid valve 58 so that pressurized air can flow into branch line 56 to operate pneumatic valve 53". Pneumatic valve 53 opens and allows air to flow through line 52 to tee 49 and then through outlet tube 50 to nozzle 51 and blow away any excess blowing sand. When it is desired to continue sandblasting, switch S3 is opened, de-energizing solenoid 58S and closing branch line 56, causing pneumatic valve 53 to close. Switch S2 is then closed to start the engine. whereupon the operation as previously described is repeated.

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The wood used for the beam must be of the first quality be straight fibers on iron and be well deposited «The resonant frequency of the beam is proportional to its thickness if the width is kept constant. As mentioned before, this is supposed to be the container, the beam and the motor having system be designed so that there is a resonance frequency of about 200 to 800 vibrations per minute, a useful value is 600 vibrations ^ e minute.

The arrangement has the advantage that the engine is a very has a long lifespan if it is against the introduction is sealed from dirt. Due to the fact that the engine has the swing weight in phase with the Vibrations of the beam rotates, the load on the motor bearings designed as ball bearings is very low « In addition, * the engine speed is proportionate low. Both of these features ensure the long life of the engine.

The material in the drying device 46 can be any common desiccants such as chlorinated lime or silica gel. Optionally, the drying device can have a condenser. If an ab-

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sorting material is used, it must be used regularly replaced and, if a capacitor is used, means must be provided to prevent it to be able to drain accumulating condensate at frequent intervals »Although» as mentioned before, a compressor as part of the sandblasting system shown, the sandblasting fan can be designed to be connected to a compressor, and if the latter has a drying device, the arrangement is such on the sandblasting blower arrangement not mandatory"

The ratio of the cross-sectional areas of the nozzle tube 64 and the outlet pipe 50 should not be too small, there sieve, otherwise deposit the Blassana in the pipe 50 and a Can cause clogging «, even if the ear is 50 is not clogged, the blowing sand can flow through the pipe at low speed as a closed stream stream, with little or no power to sandblast

The rectifier bridge 67 is expediently designed so that that it delivers a voltage of about 300 volts, and the Capacitor 76 can be useful in an order of magnitude of 60 microfarads. The time delay relay B2 is designed in such a way that it does not immediately receive the

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supplies full energy ^{1 to} the motor 41. If the engine were given full power when starting, the engine would try to run away and could very well exceed the resonance frequency without creating a dynamic coupling with the vibrations of the beam, so that the movements of the oscillating weight are in phase with the vibrations of the beam It can be seen that the invention has created a sandblasting blower and a method for sandblasting in which the amount of blown sand fed to the nozzle can be easily regulated by means of a variable resistor in the embodiment described, the resistor 73 * In addition

In addition, the amount can be adjusted to a predetermined value by so designing the milliammeter 76a is that a setting on the milliammeter corresponds to a given amount of blow sand, which the Nozzle happened in a unit of time

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Claims (2)

4 / claims 1. Sandblasting blower with a pressurized gas source, a Sehleifteittel container, one with these over a Delivery line connected blow-out nozzle for a gas-Soblei £ tittelgemisoh, devices for vibration of the grinding medium container and devices for Change in the vibration amplitude, marked by a * ■ - "attached to the free end of a one-sided Abrasive container (16) arranged on a carrier (13), an ax at this or at the free end of the support arm (13) arranged electric motor (41) with a characteristic old changing inversely to the given load Speed and one driven by the motor (41), the consisting of a support arm, abrasive container and motor, an oscillating mass (43) which gives a vibration that corresponds approximately to its basic resonance frequency. Sta.15/03 9 0 9 8 2 4/0429 IO 2. Sand jet blower according to claim I _9, characterized by a Hauptscbluß- or Reihenscbluß Slektromotoro 3 · Sandblasting blower according to claims 1 and 2, characterized by one directly on the motor shaft (42) arranged flywheel 4 «sandblasting blower according to claim 1 to 3, characterized by one of the motor (41) for overcoming the Increased inertia of the flywheel (4-3) when starting Energizing Starter Device (76) 5 ο sandblasting fan according to claim 1 to 4, characterized by a starter device lait one When energy is supplied to the engine (41), it charges and when starting it releases an increased cause.! ~ energy via the motor (41) discharging capacitor (76). 6. Sandblasting blower according to Claims 1 to 5, characterized by a Hegel resistor (73), one of which is fully switched into the engine ice when the engine is started End after a predetermined period of time after energy has been supplied to the motor (41) with the variable Tapping (80) of the rheostat (73) short cut will. 909824/0429