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 the normal operating current for the conventional contact charging of the coating material 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.
• Both too low and too high operating currents must be avoided, because in the first case insufficient ionization occurs, resulting in unsatisfactory coating efficiency (ratio between the sprayed material and the material reaching the workpiece), while in the second case there is a risk of overloading the Color mist with space charge effects, which experience shows the corona current and the ionization can suppress almost completely.
• the electrodes, their holder arrangement and other parts of the atomizer can be contaminated quickly by the sprayed-off material.
• DE-OS 34 45 946 it is known to electrostatically coat large workpieces such as e.g. Vehicle bodies automatically switch off the system to avoid a voltage breakdown between the workpiece and the coating device when the operating current increases to a threshold value which is predetermined as a function of the operating voltage which can be adjusted within a certain range.
• a threshold value which is predetermined as a function of the operating voltage which can be adjusted within a certain range.
• all current threshold values that apply to the selectable voltage values are stored together, in particular in a microprocessor, and are automatically selected during operation in accordance with the respectively set voltage.
• 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 object of the invention described here is to specify a method which is used when operating a corona discharge and constant voltage operating system largely avoids the risk of self-contamination of the spraying device.
• the high voltage generator can also be controlled in direct dependence on the air humidity in the sense of a constant corona current.
• the predetermined current value to be maintained does not have to be the same for all operating conditions.
• 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, an operating voltage that is too high can also 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 to determine whether it exceeds or in particular exceeds permissible values, preferably in the manner described 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 value 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.

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

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