Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
  • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
  • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
  • B05D1/06—Applying particulate materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
  • B05B5/08—Plant for applying liquids or other fluent materials to objects
  • B05B5/10—Arrangements for supplying power, e.g. charging power

Definitions

• the invention relates to a method according to the preamble of claim 1.
• the voltage of the high-voltage generator applied to the spraying devices was previously customary to stabilize the voltage of the high-voltage generator applied to the spraying devices to constant values, which could be set in stages, for example in the range from 60 to 100 kV, to take into account the respective operating conditions. If the voltage is kept at a constant value, problems occur, in particular, in the case of the external charging of the coating material by corona discharge, since under certain circumstances considerable fluctuations in the corona current can occur during operation.
• the corona current is significantly higher than that of the conventional contact charging of the coating materials normal operating current in the atomizer and depends not only on the electrode voltage, but also on various environmental conditions such as air humidity and possible contamination of the electrode area.
• the corona operating current can fluctuate between 100 and 300 ⁇ A when the air humidity changes between 30% and 90%, as is easily possible in practice.
• operating currents that are either too low or too high must be avoided because in the first case insufficient ionization occurs, resulting in unsatisfactory coating efficiency (ratio between sprayed-off material and the material reaching the workpiece), while in the second case there is a risk of overloading the Color mists with space charge effects exist, which experience has shown that they can almost completely suppress the corona current and ionization.
• DE-OS 34 45 946 it is known to automatically switch off the system for avoiding a voltage breakdown between the workpiece and the coating device when electrostatically coating large workpieces such as vehicle bodies, when the operating current rises to a threshold value which depends on the in a certain Range adjustable operating voltage is predetermined.
• a threshold value which depends on the in a certain Range adjustable operating voltage is predetermined.
• all current threshold values that apply to the selectable voltage values are together in particular stored in a microprocessor and selected automatically during operation according to the voltage set.
• a warning signal can also initially only be generated if the current measured continuously during operation exceeds an intermediate threshold value between the normal value and the switch-off threshold value.
• the invention described here is based on the object of specifying a method for operating a corona discharge and with constant voltage largely avoids the risk of self-contamination of the spraying device.
• the high-voltage generator can also be controlled as a direct function of the air humidity in the sense of a constant corona current.
• the predetermined current value to be maintained need not be the same for all operating conditions.
• the supply voltage of the electrodes has to be changed to keep the operating current constant, these changes also allow conclusions to be drawn about correct or faulty operation. For example, in the event of a short circuit, increasing contamination, or an approach of the workpiece to the spraying device that is dangerous with respect to a voltage breakdown, there is a tendency for a steep current rise, which is counteracted by a corresponding reduction in the voltage.
• the supply voltage of the electrodes is measured continuously, and if it falls below a limit value, an alarm signal can be generated and / or the coating system can be switched off.
• the voltage limit value can be set depending on the respective operating conditions and changed automatically.
• An alarm signal can also be generated if the supply voltage changes impermissibly quickly during the control, or if the operating current changes by more than a permissible amount within a specified time, for example if the current control fails or works too slowly. Finally, too high Operating voltage trigger an error message.
• the described regulation of the corona operating current to a certain, usually constant value takes place during normal coating operation.
• the measured operating current can first be monitored by comparing it with predetermined voltage-dependent data as to whether it exceeds or in particular exceeds permissible values, preferably in that mentioned in DE-OS 34 45 946 familiar way.
• an alarm signal is generated or the system is switched off, while if the intended current value is reached without errors, the current control is switched on, it now being determined for operational monitoring whether the supply voltage remains above the prescribed minimum value.
• the system can be switched over from current threshold operation to constant current operation automatically, for example when a predetermined voltage of the high-voltage generator is exceeded after it has been switched on.

Landscapes

• Electrostatic Spraying Apparatus (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)

Applications Claiming Priority (2)

Publications (4)

Family

ID=6323791

Family Applications (1)

Country Status (19)

Cited By (1)

Families Citing this family (13)

Family Cites Families (19)

• 1987
  • 1987-03-23 DE DE19873709510 patent/DE3709510A1/de not_active Withdrawn
• 1988
  • 1988-03-17 NZ NZ223921A patent/NZ223921A/xx unknown
  • 1988-03-17 EP EP88104265A patent/EP0283936B2/fr not_active Expired - Lifetime
  • 1988-03-17 DE DE8888104265T patent/DE3871578D1/de not_active Expired - Lifetime
  • 1988-03-17 US US07/169,314 patent/US4851253A/en not_active Expired - Lifetime
  • 1988-03-17 ES ES88104265T patent/ES2004324T5/es not_active Expired - Lifetime
  • 1988-03-21 SU SU884355362A patent/SU1766240A3/ru active
  • 1988-03-22 DD DD88313880A patent/DD268176A5/de not_active IP Right Cessation
  • 1988-03-22 CN CN88101598A patent/CN1016583B/zh not_active Expired
  • 1988-03-22 SK SK1873-88A patent/SK280705B6/sk unknown
  • 1988-03-22 BR BR8801280A patent/BR8801280A/pt unknown
  • 1988-03-22 KR KR1019880003046A patent/KR930005171B1/ko not_active Expired - Lifetime
  • 1988-03-22 AU AU13377/88A patent/AU599290B2/en not_active Ceased
  • 1988-03-22 HU HU881440A patent/HUT57087A/hu unknown
  • 1988-03-22 FI FI881346A patent/FI88466C/fi not_active IP Right Cessation
  • 1988-03-22 CA CA000562068A patent/CA1288295C/fr not_active Expired - Lifetime
  • 1988-03-22 CZ CS881873A patent/CZ283607B6/cs not_active IP Right Cessation
  • 1988-03-22 MX MX010848A patent/MX169076B/es unknown
  • 1988-03-23 PL PL1988271382A patent/PL157799B1/pl unknown
  • 1988-03-23 JP JP63070814A patent/JPH0657338B2/ja not_active Expired - Fee Related

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