EP0325381A2 - A control system for operating a spray dampening system - Google Patents
A control system for operating a spray dampening system Download PDFInfo
- Publication number
- EP0325381A2 EP0325381A2 EP89300326A EP89300326A EP0325381A2 EP 0325381 A2 EP0325381 A2 EP 0325381A2 EP 89300326 A EP89300326 A EP 89300326A EP 89300326 A EP89300326 A EP 89300326A EP 0325381 A2 EP0325381 A2 EP 0325381A2
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- EP
- European Patent Office
- Prior art keywords
- pulse sequence
- speed
- rectangular pulse
- spray
- value
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41F—PRINTING MACHINES OR PRESSES
- B41F33/00—Indicating, counting, warning, control or safety devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41F—PRINTING MACHINES OR PRESSES
- B41F7/00—Rotary lithographic machines
- B41F7/20—Details
- B41F7/24—Damping devices
- B41F7/30—Damping devices using spraying elements
Definitions
- the present invention relates to a liquid sprayer apparatus, especially of the type utilized in a pulsed spray dampener system.
- Various systems have been proposed in the past for applying a fluid to the rollers of printing presses. These fluids may be used, for example, for dampening or cleaning the rollers, or for preventing printing offset.
- One type system dampens the rollers by spraying a fluid most from nozzle assemblies positioned adjacent the rollers. Typically, a plurality of nozzle assemblies are aligned in a spray bar.
- U.S. Patent No. 4,469,024 to Schwartz et al relates to a pulsed spray dampener wherein the amount of fluid which is dispensed is controlled by a measured press speed.
- a speed sensor generates a sinusoidal sensor signal having a frequency related to the press speed.
- a pulse width modulator receives the sinusoidal sensor signal and generates a square wave control signal wherein the pulse duration is maintained constant. The time between pulses in the square wave control signal is varied as a function of press speed.
- the control signal is converted to pneumatic pulses used operate air-actuated valves which supply fluid to the spray nozzles.
- a speed sensor provides a sensor signal to a master controller which, on the basis of the sensor signal value, selects one of a plurality of oscillating electrical signals having discrete frequencies.
- the selected frequency signal is supplied to a monostable which produces a fixed-length pulse in response to the leading edge of each cycle of the frequency signal.
- the monostable pulses are then used to operate spray nozzle solenoids. The width of the monostable pulse may be adjusted manually.
- U.S. Patent No. 3,926,115 to Alsop discloses a spray dampening apparatus wherein the fluid output may be temporarily varied by partial or complete interruption of the spray.
- a solid obstructor may be placed in the spray path or a deflecting air blast may be used to vary the spray output.
- the output spray may be controlled by varying the position of various mechanical members.
- the present invention provides a liquid sprayer assembly comprising a valve, a nozzle including a liquid spray outlet at a front end thereof and a valve seat at a rear end thereof, means releasably mounting said nozzle to said valve, said valve comprising a valve housing including a throughbore communicating with a liquid inlet, a solenoid plunger slidably mounted in said throughbore for reciprocable movement therein, a valve stem removably mounted at a front end of said plunger and including a front sealing surface arranged to contact said valve seat, said valve seat, said valve stem, said plunger, and said nozzle means being coaxially arranged, characterized in that said valve stem is detachable from said plunger in response to the application of suitable forces to a front end of said valve stem, said throughbore being wide enough to permit forward removal of said valve stem from said plunger when said nozzle means has been detached from said valve means.
- the present invention also provides a control system for operating a spray dampening system having a plurality of spray nozzles for supplying dampening fluid to a roller of a printing press, comprising means for obtaining a speed signal representative of a printing speed of said printing press, means for producing a first rectangular pulse sequence, and means for driving said nozzles in response to said first rectangular pulse sequence; characterized in that when the value of said speed signal is below a first speed value each rectangular pulse in said first pulse sequence has a fixed duration and the time period between adjacent pulses is varied in response to said speed signal, and when the value of said speed signal is above said first speed value the time period between adjacent pulses in said first pulse sequence is fixed and the duration of the pulses is varied in response to said speed signal.
- the present invention further provides a method for controlling the operation of the spray dampening system having a plurality of solenoid-operated spray nozzles for supplying dampening fluid to a roller of a printing press, comprising the steps of obtaining a signal representative of a printing speed of said printing press, generating a first rectangular pulse sequence, and driving said solenoids in response to said first rectangular pulse sequence; characterized in that when said speed of said printing press is below a first speed value each rectangular pulse in said first rectangular pulse sequence has a fixed duration and the time period between adjacent pulses is varied as a function of said speed signal, and when the speed of said printing press is above said first speed value the period between adjacent pulses in said first rectangular pulse sequence is fixed and the duration of the pulses is varied as a function of said speed signal.
- the present invention still further provides a spray dampening system for providing a dampening fluid to a moving surface, comprising means for sensing the speed of said moving surface and for providing a signal related to the sensed speed, at least one spray bar including a linear array of spray nozzles arranged to provide overlapping spray patterns on said moving surface, means operatively coupled with said sensing means for generating a first rectangular pulse sequence having a duty cycle which is related to the value of said signal provided by said speed sensing means, and means for driving said nozzles in accordance with said first rectangular pulse sequence; characterized in that when said sensed speed is below a first speed value each rectangular pulse in said first pulse sequence has a fixed duration and the time period between adjacent pulses is varied in response to said sensed speed signal and when said sensed speed is above said first speed value the time period between adjacent pulses in said first pulse sequence is fixed and the duration of the pulses is varied in response to said sensed speed signal.
- a liquid sprayer assembly comprises a valve and a nozzle releasably mounted to the valve.
- the nozzle includes a liquid outlet at a front end thereof and a valve seat at a rear end thereof.
- the valve comprises a valve housing including a throughbore communicating with a liquid inlet.
- a solenoid plunger is slidably mounted in the throughbore for reciprocable movement therein.
- a valve stem is removably mounted at a front end of the plunger and includes a front sealing surface arranged to contact the valve seat.
- the valve seat, the valve stem, the plunger, and the nozzle are coaxially arranged.
- the thoughbore is wide enough to permit forward removal of the valve stem from the plunger when the nozzle is removed from the valve. Accordingly, only minimal disassembly of the apparatus is required in order to replace the sealing surface.
- the presence of the valve seat directly in the valve nozzle prevents the occurrence of excessive pressure build-ups in the liquid being sprayed.
- a spray dampener control system includes means for sensing the printing press speed. In response to the sensed press speed, a rectangular pulse sequence is generated. When the sensed press speed is below a particular value, each pulse in the rectangular pulse sequence has a fixed duration and the time period between adjacent pulses is varied in response to the press speed. When the press speed is above the particular value, the time period between adjacent pulses is fixed and the duration of the pulses is varied in response to the sensed speed. Spray nozzles are driven in response to the rectangular pulse sequence.
- FIG. 1 Depicted in FIG. 1 is a portion of an offset printing apparatus 10 comprising a plate cylinder roll 12, a water-form roll 14, a dampening roll 16, and a spray dampener mechanism 18 according to the present invention.
- the spray dampener mechanism 18 emits a pulsating spray of wetting liquid, such as water which may contain certain additives, the liquid being sprayed onto the dampener roll and from there transferred to the water-form roll.
- Each sprayer assembly 32 comprises a nozzle section 38 and a valve section 40.
- the nozzle section 38 comprises a generally cylindrical nozzle housing 42 (FIG. 7) which includes a transverse slot 44 at its front end.
- a nozzle element 46 mounted by press-fit within a center bore of the nozzle housing 42 is a nozzle element 46, preferably formed of hard, wear-resistant material such as tungsten carbide.
- Press-fit into a rear end of the center bore is a retaining ring 48, and press-fit into a center hole of the ring 48 is a valve seat 50.
- the valve seat is of generally hollow cylindrical shape and includes a tapered end 52.
- the nozzle element 46 includes a slit 54 in its front end, which slit communicates with a center passage 56 of the valve seat 50 through a center passage 58 in the nozzle element 46.
- the nozzle housing 42 is removably disposed in the front end of a throughbore 59 formed in a cap 60 (FIG. 6) of the type described in U.S. Patent No. 4,527,745 to Butterfield et al.
- the cap 60 includes slots 62 in its outer wall for reasons to be explained hereinafter.
- a conventional plug-in type solenoid coil casing 96 mounted on a rear end of the post 76. That casing includes a bore 98 through which the post 76 extends. An annular external groove 100 is formed at the rear end of the post 76 to receive a retaining ring (not shown) or the like for retaining the casing 96 on the post.
- a spring (not shown) may be disposed between such retaining ring and a rear surface 97 of the casing to bias the casing against the plate 82. The spring would be yieldable to permit the casing to be displaced slightly away from the plate 82 in order to be rotated about the axis of the post 76 so that the three plug-in prongs 102 could be repositioned.
- the post 76 has a hollow front end into which a valve plunger 104 is slidably disposed so as to be positioned within the solenoid coil casing 96.
- the plunger is adapted to be displaced rearwardly (i.e., upwardly as viewed in FIG. 6) in response to energization of the solenoid coil containing within the casing 96.
- a coil compression spring 106 surrounds the plunger 104 and acts between the flange 78 and a flange 108 situated at a front end of the plunger 104.
- the flange 108 may be formed by a split retaining ring for example.
- valve stem 110 Removably mounted in a front hollow end of the plunger is a valve stem 110.
- the valve stem 110 includes a rear portion 112 mounted by friction-fit within the plunger 104, and a front portion 114 of enlarged cross-section which slides within a throughbore 116 of a body member 118.
- the body member includes external threading 120 on its rear end which is screwed into the internal threading 74 of the valve housing.
- the body member 118 includes an internal bushing 119 within which a front end of the valve stem 110 slides.
- the valve stem includes a plurality of longitudinal channels 121 in its outer periphery for conducting liquid forwardly past the bushing 119 (see FIG. 10).
- a disc 122 Projecting from the front end of the stem 110 is a disc 122 formed on a resilient material.
- the disc 122 is of larger diameter than the rear end of the passage 56 formed in the valve seat 50 and is adapted to bear sealingly thereagainst under the bias of the spring 106. It will be appreciated that the passages 56, 58, the stem 114, the plunger 104, and the post 76 are aligned along a common longitudinal axis.
- the stem 110 is no longer in cross-section than the throughbore 116 of the body 118, whereby the stem 114 can be pulled out of the plunger 105 and completely out of the sprayer assembly 32 in a forward direction after the cap 60 and nozzle section 38 have been removed therefrom.
- the stem could be attached to the plunger by other quick-release connections such as a threaded connection.
- Attachment and removal of the nozzle section 38 is effected by the cap 60 in a conventional manner. That is, the slots 62 in the cap are arranged to receive radially projecting lugs 124 formed on the outer wall of the body 118.
- the side walls of the slots 62 include cam portions 126 which serve to draw the cap toward the body 118 in response to relative rotation therebetween.
- This causes the front wall 128 to be forced longitudinally against an elastic seal ring 130 positioned between the front wall 128 and a rear wall 132 of the nozzle housing 42. Counter-rotation of the cap is yieldably resisted by thus-compressed ring 130.
- the ring 130 also creates a fluid seal once it has been compressed in that fashion.
- pressurized liquid is introduced to the sprayer assembly through the port 71. If the solenoid is de-energized, i.e., in a non-spraying mode, the valve stem is biased against the valve seat 50 to close the nozzle element. Once the solenoid has been actuated, the plunger and stem are retracted, thereby unblocking the valve seat. Pressurized liquid is immediately ejected through the valve outlet 54 and onto the roll. After the sealing disc 122 has become worn, removal thereof is achieved by simply unscrewing the body member 118 and pulling the stem 110 axially from the plunger. Insertion of a new stem is achieved by reversing those steps.
- a prior art nozzle assembly 236, depicted in FIGS. 11-13, comprises a nozzle section 238 and a valve section 240.
- the nozzle section 238 comprises a generally cylindrical nozzle housing 242 which includes a transverse slot 244 at its front end.
- the nozzle element 246 includes a slit 254 in its front end, which slit communicates with a center passage 258 in the nozzle element 246.
- the nozzle housing 238 if removably disposed in the front end of a throughbore formed in a cap 260 (FIG. 12) of the type described in U.S. Patent No. 4,527,745 to Butterfield et al.
- the cap 260 includes slots 262 in its outer wall for reasons to be explained hereinafter.
- the valve section 240 comprises a valve housing 270 which includes first and second threaded bores 271, 272 separated by a partition 273.
- the bores 271, 272 are aligned with each other and with the passage 258 in the nozzle housing 242.
- a third bore 274 Disposed in the valve housing 270 perpendicularly to the bores 271, 272 is a third bore 274. That third bore 274 communicates with the first and second bores 271, 272, by first and second passages 275A, 275B, respectively.
- Removably attached to a rear end of the valve housing is a hollow post 276.
- the post 276 includes an enlarged flange 278 at its front end which fits into a counterbore 280 at a rear end of the third bore 274.
- a plate 282 has a central opening 284 through which the post 276 passes, the plate 282 being attached to the rear side 286 of the valve housing 270 by means of screws 288.
- a resilient seal ring 290 is disposed between the plate 282 and the flange 278 to engage a flared rear end 292 of the counterbore 280 in order to create a fluid seal therewith.
- a conventional plug-in type solenoid coil casing 296 mounted on a rear end of the post 276. That casing includes a bore 298 through which the post 276 extends.
- An annular external groove 300 is formed at the rear end of the post 276 to receive a retaining ring (not shown) or the like for retaining the casing 296 on the post.
- a spring (not shown) may be disposed between such retaining ring and the rear side 297 of the casing to bias the casing against the plate 282. Such spring would be yieldable to permit the casing to be displaced slightly away from the plate 282 in order to be rotated about the axis of the post 276 so that the three plug-in prongs 302 could be repositioned.
- the post 276 has a hollow front end into which a valve plunger 304 is slidably disposed so as to be positioned within the solenoid coil casing 296.
- the plunger is adapted to be displaced rearwardly (i.e., to the right in FIG. 12) in response to energization of the solenoid coil contained within the casing 296.
- a coil compression spring 306 surrounds the plunger 304 and acts against the flange 278 and a flange 308 situated at a front end of the plunger 304.
- the flange 308 may be formed by a split retaining ring for example.
- an elastic sealing member 310 Disposed in a front end of the plunger 304 is an elastic sealing member 310 which is adapted to bear against a tapered seat 312 surrounding the passage 275A under the bias of the spring 306 whenever the solenoid coil is not energized. In so doing, the passage 275A will be closed, while the passage 275B will remain open.
- the plunger 304 includes at least one longitudinal channel 314 which is adapted to conduct a flow of fluid from the passage 275B to the rear end of the hollow post 276. Such fluid would flow around an outer edge of the flange 308, though the channel 314 and through a small hole (not shown) at the rear of the post 276 and from there to a suitable conduit (not shown) connected to the rear end of the post 276.
- the slots 262 in the cap are arranged to receive radially projecting lugs 324 formed on the outer wall of the body 318.
- the side walls of the slots 262 include cam portions 326 which serve to draw the cap toward the body 318 in response to relative rotation therebetween. This causes a front wall of the body member 318 to be forced longitudinally against an electric seal ring (not shown) positioned between the front wall and a rear wall of the nozzle housing 242.
- pressurized fluid is delivered to the second bore 272 and flows through the passage 275B. If the solenoid is not energized, the valve plunger 304 closes the passage 275A, so that the fluid travels through the channel 314 and out the rear end of the post 276 to a suitable sump. If the valve is energized, causing the plunger 304 to be retracted, the passage 275A is opened, enabling fluid to flow therethrough and from there to the nozzle element. When the plunger is retracted, a seal at the wall 330 of the plunger engages the small hole (not shown) at a rear end of the plunger to close the flow to the sump.
- a sprayer assembly according to the present invention enables a worn valve stem, to be replaced by merely unscrewing the body member 118 and pulling forwardly on the stem 110 with a force sufficiently strong to overcome the resistance of the friction-fit of the stem portion 112 within the plunger 104. A new stem can then be inserted by being pushed into the plunger. Therefore, no appreciable disassembly of the valve assembly is required.
- a conventional prior art nozzle section can be converted into a nozzle section suitable for use in the present invention.
- Such an arrangement enables fluid flow to be terminated directly at the rear side of the nozzle section.
- the short distance between the valve and the spray slit 54 avoids the occurrence of pressure surges and dripping, and avoids the need to divert unused pressurized fluid to a sump when the valve is closed. Hence, there is no need to dispose of large amounts of unused liquid.
- a signal 402 includes a sequence of rectangular pulses P and may be used for controlling actuation of the spray nozzle solenoids. Briefly, when the signal 402 is in a "HIGH” or “ON” state, current is supplied to actuate a spray nozzle solenoid. The solenoid, and thus the spray nozzle, is de-actuated when the signal 402 is in a "LOW” or “OFF” state.
- the duty cycle of the pulse sequence is determined by the width of a pulse P relative to the cycle time. In other words, the duty cycle D may be determined by taking the ratio of the ON time t ON and the cycle time t TOT .
- the cycle time t TOT is, of course, the sum of the ON time t ON and the OFF time t OFF .
- the duty cycle of the signal 402 may be varied. a higher duty cycle would increase the spray output from the dampener. For example, a duty cycle of 1 would mean that the signal 402 stayed in the ON position at all times and, thus, the spray nozzles would likewise remain ON at all times. The spray nozzles would remain in an OFF state for a duty cycle of 0.
- the pulse width t ON is roughly one-third of the total cycle time t TOT .
- the duty cycle for the illustrative signal 402 in Fig. 14 would be approximately 0.33, and a spray nozzle controlled by the signal would be ON roughly 33.3% of operating time.
- the duty cycle may be varied by changing one or both of the pulse width t ON on the time t OFF between adjacent pulses of the pulse sequence defined by the signal 402.
- system limitations often prevent proper operation of the spray dampener beyond particular operating parameters.
- valve and nozzle limitations prevent proper operation for pulse widths below a certain value.
- systems which vary ON time often suffer from poor spray patterns during periods in which spray output is low.
- systems which vary the duty cycle by adjusting OFF time confront problems associated with roller drying when relatively long periods of time elapse between spray pulses, particularly during high speed press operation.
- the present invention overcomes these difficulties.
- the amount of dampening fluid dispensed by the spray dampener preferably has a nonlinear relationship to press speed. At press speeds below a certain speed S0, spray dampener output may be inhibited. This situation normally would occur as the press was being brought up to printing speed.
- the dampening percentage i.e., the percentage of time during which the nozzles release dampening fluid, increases linearly with press speed at a first rate.
- the dampening percentage varies linearly with press speed at different rates.
- the dampening curve may include a purge signal which would output when the printing press is initially brought to speed s0.
- the speeds at which the dampening curve 404 encounters a change in slope, and the particular slopes for the individual segments of the dampening curve will depend on the printing press in which the spray dampening system is used.
- the pulse width t ON of nozzle control pulses P is set at a predetermined value e.g., 20 microseconds, which is sufficiently long to ensure a proper spray pattern.
- the dampening percentage may then be varied by adjusting the time period between adjacent pulses in the pulse sequence.
- the time period between adjacent pulses is set at a predetermined value, e.g., 400 microseconds, which ensures that the printing press rollers will not dry excessively between pulses of spray during high speed press operation.
- the dampening percentage is then varied by adjusting the pulse width of the pulses P. In this way, the present invention obtains proper spray patterns and effective operation throughout a broad range of operating conditions.
- the pulse width between speeds S0 and S1 may be set at a first value, for example 20 microseconds, and the pulse width between speeds S1 and S2, when dampening requirements are higher, may be set at a higher second value such as 30 microseconds.
- the time period between adjacent pulses of the pulse sequence for press speeds between speeds S2 and S3 may be set at one value, for example, 500 microseconds, and at another value such as 400 microseconds for press speeds above speed S3.
- finer spray control is provided by adding additional set points along the dampening curve 404. Of course, if desired even more set points could be sprovided on the dampening curve to permit even finer spray control.
- a control system in accordance with the present invention includes a main controller 406 including a central processing unit (CPU) 408, a system memory 410, and an input/output (I/O) device 412. Additionally, a display device (not shown) such as a liquid crystal display, a light emitting diode (LED) display, or a cathode ray tube (CRT) may be provided to permit information concerning operating parameters and the like to be conveyed to a user.
- the system memory 410 preferably includes a non-volatile memory portion for storing one or more dampening curves.
- Dampening curves may be preprogrammed into the system memory 410 or, preferably, the dampening curves may be downloaded from a computer or from a terminal device.
- a serial communications line 414 is provided to permit the controller 406 to communicate with a computer.
- a terminal device 416 may communicate with the controller 406 through a communication line 418.
- the dampening curve information may be downloaded to the controller 406 through an appropriate serial interface, such as a standard RS 422 interface.
- This information may be supplied to CPU 408 for storage in the system memory 410.
- the system memory 410 includes a programmable read-only memory device (PROM).
- the dampening curve information may be supplied to the CPU 408 from a terminal device 416.
- a user can directly store an appropriate dampening curve in the system memory 410.
- the CPU 408 is adapted to receive a press speed indication signal on an input line 420.
- the press speed indication signal may be obtained from a standard tachometer generator, Hall effect proximity sensor or other appropriate sensor. Additionally, in modern printing presses which include a printing computer, a press speed indication signal might already be available in the press computer. In this case, the press speed indication signal may be obtained directly from the printing computer.
- the CPU 408 in response to the speed indication signal, retrieves a record from the system memory 410 which contains information relating to the parameters of a spray nozzle actuation control signal. For instance, the speed indication signal might be converted into a memory address value. The contents stored in the system memory 410 at this address might then provide information indicating a duty cycle value for the spray nozzle actuation control signal. Based upon the stored duty cycle value and the speed indication signal, the parameters of the spray nozzle actuation signal may be calculated by the CPU 408.
- a speed-indication signal indicating a speed S4 is obtained by the main controller 406
- a record stored in system memory 410 in the appropriate memory location would including a duty cycle value 0.15 corresponding to 15% dampening.
- speed S4 is lower than speed S2
- the pulse width t ON is set at a fixed value such as 20 microseconds.
- the pulse sequence parameters may similarly be calculated when the press speed value obtained by the main controller 406 is greater than speed S2.
- the appropriate memory location in system memory 410 would contain a record including a duty cycle value 0.22.
- the main controller 406 may calculate either the pulse width t ON or the time period t OFF .
- the CPU 408 utilizes count values corresponding to the pulse width and the time period between pulses.
- the CPU 408 may generate a rectangular pulse sequence by providing a HIGH output signal for C ON clock cycles and a LOW output signal for C OFF clock cycles.
- Count values C ON and C OFF may themselves be stored in system memory 410 for retrieval by the CPU 408 in response to the press speed indication signal.
- the CPU 408 produces pulse sequences one through six which are output by I/O unit 412 on first through sixth output lines 422, 424, 426, 428, 430 and 432, respectively.
- Output lines 422 and 424 are connected with the respective channels of a standard dual channel optocoupler 434.
- output lines 426 and 428 are connected with the respective channels of a dual channel optocoupler 436
- output lines 430 and 432 are connected with respective channels of a dual channel optocoupler 438.
- the optocouplers serve to help isolate the main controller 406 from possible damage caused by transient surges and the like.
- spray bar 440 may be provided with eight spray nozzles N1-N8 arranged in a linear array.
- Spray bar 440 is preferably adapted to supply dampening fluid for a multipage printing press.
- the spray bar 440 provides dampening fluid for a four page printing press.
- nozzles N1 and N2 primarily control dampening of page 1
- nozzles N3 and N4 primarily control dampening of page 2
- nozzles N5 and N6 primarily control dampening of page 3
- nozzles N7 and N8 primarily control dampening of page 4.
- the spray patterns from adjacent nozzles overlap slightly.
- end nozzles N1 and N8 are situated at the outermost portions of the linear array of nozzles, there is no dampening contribution from overlapping spray from an adjacent outer nozzle.
- the portions of the dampening roller adjacent the outer portions of pages 1 and 4 receive somewhat less dampening fluid than the remaining portions of the roller.
- the outer portions of the roller often have a greater tendency to heat than the intermediate portions of the roller. Accordingly, the portion of the roller which requires the greatest amount of dampening fluid often receives the least. It has been suggested that this problem may be overcome by using larger spray nozzles on the outer portions of the spray bar. This solution, however, often leads to additional problems associated with the use of differing spray nozzles o the spray bar. Additionally, maintenance and manufacture of the spray bars is complicated by this structure.
- nozzle N1 is controlled by channel 1; nozzle N2 is controlled by channel 2; nozzles N3 and N4 are controlled by channel 3; nozzles N5 and N6 are controlled by channel 4; nozzle N7 is controlled by channel 5; and nozzle N8 is controlled by channel 6.
- the duty cycle of the pulse sequences on control channels 1 and 6 may be increased.
- the duty cycle of the pulse sequence on control channel 1 may be slightly higher than the duty cycle of the pulse sequence on control channel 2.
- the duty cycle of the pulse sequence on control channel 8 may be slightly higher than the duty cycle of the pulse sequence on control channel 7.
- the duty cycle of the pulse sequences on control channels 1 and 8 are functionally related to the duty cycle of the pulse sequences on control channels 2 and 7, respectively.
- the duty cycles of the pulse sequences on control channels 1 and 8 are 4% higher than the duty cycles of the pulse sequences on control channels 2 and 7, respectively.
- the duty cycle of nozzle N1 will be 1.04 times that of nozzle N2.
- nozzles N1 and N8 each have a dedicated control channel, the different duty cycles may be accommodated.
- the CPU 408 may be programmed to calculate the modified duty cycle for nozzles N1 and N8 and adjust the pulse sequences on output lines 422 and 432 accordingly.
- Dedicated power transistors TR1 and TR8 control nozzles N1 and N8 in accordance with the modified pulse sequences.
- each page is provided with a separate control channel.
- nozzles N3 and N4 page 2 are operated by channel 3.
- Nozzles N5 and N6 page 3 are controlled by channel 4.
- nozzles N2 and N7 also have individual control channels CH2 and CH5, respectively.
- the duty cycle of the pulse sequence on channel 1 preferably is functionally related to the duty cycle of the pulse sequence on channel 2
- the duty cycle of the pulse sequence on channel 8 preferably is functionally related to the duty cycle of the pulse sequence on channel 7.
- the operating characteristics of the main controller may be varied in accordance with user instructions. Accordingly, user commands may to input to the main controller 406 through terminal 416. Additionally, the main controller 406 may include keypad or specific control knobs (not shown). If, for example, page 2 required increased dampening, a user could instruct the CPU 408 to increase the duty cycle of the pulse sequence on channel 3.
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Abstract
Description
- The present invention relates to a liquid sprayer apparatus, especially of the type utilized in a pulsed spray dampener system.
- Various systems have been proposed in the past for applying a fluid to the rollers of printing presses. These fluids may be used, for example, for dampening or cleaning the rollers, or for preventing printing offset. One type system dampens the rollers by spraying a fluid most from nozzle assemblies positioned adjacent the rollers. Typically, a plurality of nozzle assemblies are aligned in a spray bar.
- A sprayer assembly which has heretofore been employed is described later in this text in detail in connection with FIGURES 11-13. Briefly, that sprayer assembly is characterized by a nozzle section and a valve having a plunger positioned at an appreciable distance behind the nozzle section. Pressurized fluid is supplied to the valve and is directed to a sump when the valve is closed and to the nozzle section when the valve is open. The plunger is reciprocated by a solenoid to produce a pulsating spray.
- When the front sealing face of the plunger becomes worn, it is necessary to disassemble the solenoid mechanism in order to replace the plunger. This is a time-consuming task which must periodically be performed on all of the nozzle assemblies. Moreover, the need to conduct fluid to a sump when the valve is closed results in wasted fluid which must be disposed of. On the other hand, it has been found that if the feature of conducting pressurized fluid to a sump is eliminated, there will occur, upon opening of the valve, an excessive pressurizing of residual fluid remaining in the passage between the nozzle element and the valve plunger which can result in an excessive amount of fluid being sprayed, as well as a dripping of fluid after the valve has been closed. However, by conducting the pressurized fluid to a sump, no pressure build-ups will occur.
- Therefore, it would be desirable to provide a sprayer assembly in which the sealing face can be replaced with minimal time and effort, no excessive pressure build-ups occur, and there is no need to dispose of unused liquid.
- U.S. Patent No. 4,469,024 to Schwartz et al relates to a pulsed spray dampener wherein the amount of fluid which is dispensed is controlled by a measured press speed. In the disclosed embodiment, a speed sensor generates a sinusoidal sensor signal having a frequency related to the press speed. A pulse width modulator receives the sinusoidal sensor signal and generates a square wave control signal wherein the pulse duration is maintained constant. The time between pulses in the square wave control signal is varied as a function of press speed. The control signal is converted to pneumatic pulses used operate air-actuated valves which supply fluid to the spray nozzles.
- Another spray dampener system is disclosed in U.S. Patent No 4,649,818 to Switall et al. A speed sensor provides a sensor signal to a master controller which, on the basis of the sensor signal value, selects one of a plurality of oscillating electrical signals having discrete frequencies. The selected frequency signal is supplied to a monostable which produces a fixed-length pulse in response to the leading edge of each cycle of the frequency signal. The monostable pulses are then used to operate spray nozzle solenoids. The width of the monostable pulse may be adjusted manually.
- U.S. Patent No. 3,926,115 to Alsop discloses a spray dampening apparatus wherein the fluid output may be temporarily varied by partial or complete interruption of the spray. A solid obstructor may be placed in the spray path or a deflecting air blast may be used to vary the spray output. In the spray dampener disclosed in U.S. Patent No. 3,924,531 to Klinger, the output spray may be controlled by varying the position of various mechanical members.
- All of the known spray dampeners have had several drawbacks. For example, pulsed spray dampeners often encounter difficulties which lead to poor spray patterns and the like. In a system wherein the amount of dampening fluid is varied by changing the "ON" time of the spray nozzles, control of the dampening fluid output during low speed press operation is restricted by physical limitations in the spray nozzles, valves, and the like. Additional, in systems wherein the "OFF" time of the spray nozzles is controlled, the controller is limited by the possibility of drying when there are long periods of time between spray pulses. Systems using a physical technique to vary spray output encounter difficulties in obtaining a proper spray pattern. Accordingly, there exists a need for a spray dampening system which overcomes the difficulties confronted in earlier spray dampening systems.
- It would be desirable to provide a spray dampening system which easily and effectively adjusts to changes in operating parameters.
- It would be further desirable to provide a spray dampening system having an improved spray pattern.
- It would also be desirable to provide an improved pulse spray dampening system for wetting a printing press roller wherein the amount of dampening fluid sprayed on the roller is varied in accordance with the speed of the printing press and a programmed dampening curve.
- The present invention provides a liquid sprayer assembly comprising a valve, a nozzle including a liquid spray outlet at a front end thereof and a valve seat at a rear end thereof, means releasably mounting said nozzle to said valve, said valve comprising a valve housing including a throughbore communicating with a liquid inlet, a solenoid plunger slidably mounted in said throughbore for reciprocable movement therein, a valve stem removably mounted at a front end of said plunger and including a front sealing surface arranged to contact said valve seat, said valve seat, said valve stem, said plunger, and said nozzle means being coaxially arranged, characterized in that said valve stem is detachable from said plunger in response to the application of suitable forces to a front end of said valve stem, said throughbore being wide enough to permit forward removal of said valve stem from said plunger when said nozzle means has been detached from said valve means.
- The present invention also provides a control system for operating a spray dampening system having a plurality of spray nozzles for supplying dampening fluid to a roller of a printing press, comprising means for obtaining a speed signal representative of a printing speed of said printing press, means for producing a first rectangular pulse sequence, and means for driving said nozzles in response to said first rectangular pulse sequence; characterized in that when the value of said speed signal is below a first speed value each rectangular pulse in said first pulse sequence has a fixed duration and the time period between adjacent pulses is varied in response to said speed signal, and when the value of said speed signal is above said first speed value the time period between adjacent pulses in said first pulse sequence is fixed and the duration of the pulses is varied in response to said speed signal.
- The present invention further provides a method for controlling the operation of the spray dampening system having a plurality of solenoid-operated spray nozzles for supplying dampening fluid to a roller of a printing press, comprising the steps of obtaining a signal representative of a printing speed of said printing press, generating a first rectangular pulse sequence, and driving said solenoids in response to said first rectangular pulse sequence; characterized in that when said speed of said printing press is below a first speed value each rectangular pulse in said first rectangular pulse sequence has a fixed duration and the time period between adjacent pulses is varied as a function of said speed signal, and when the speed of said printing press is above said first speed value the period between adjacent pulses in said first rectangular pulse sequence is fixed and the duration of the pulses is varied as a function of said speed signal.
- The present invention still further provides a spray dampening system for providing a dampening fluid to a moving surface, comprising means for sensing the speed of said moving surface and for providing a signal related to the sensed speed, at least one spray bar including a linear array of spray nozzles arranged to provide overlapping spray patterns on said moving surface, means operatively coupled with said sensing means for generating a first rectangular pulse sequence having a duty cycle which is related to the value of said signal provided by said speed sensing means, and means for driving said nozzles in accordance with said first rectangular pulse sequence; characterized in that when said sensed speed is below a first speed value each rectangular pulse in said first pulse sequence has a fixed duration and the time period between adjacent pulses is varied in response to said sensed speed signal and when said sensed speed is above said first speed value the time period between adjacent pulses in said first pulse sequence is fixed and the duration of the pulses is varied in response to said sensed speed signal.
- In accordance with the present invention, a liquid sprayer assembly comprises a valve and a nozzle releasably mounted to the valve. The nozzle includes a liquid outlet at a front end thereof and a valve seat at a rear end thereof. The valve comprises a valve housing including a throughbore communicating with a liquid inlet. A solenoid plunger is slidably mounted in the throughbore for reciprocable movement therein. A valve stem is removably mounted at a front end of the plunger and includes a front sealing surface arranged to contact the valve seat. The valve seat, the valve stem, the plunger, and the nozzle are coaxially arranged. The thoughbore is wide enough to permit forward removal of the valve stem from the plunger when the nozzle is removed from the valve. Accordingly, only minimal disassembly of the apparatus is required in order to replace the sealing surface. The presence of the valve seat directly in the valve nozzle prevents the occurrence of excessive pressure build-ups in the liquid being sprayed.
- In accordance with the present invention, a spray dampener control system includes means for sensing the printing press speed. In response to the sensed press speed, a rectangular pulse sequence is generated. When the sensed press speed is below a particular value, each pulse in the rectangular pulse sequence has a fixed duration and the time period between adjacent pulses is varied in response to the press speed. When the press speed is above the particular value, the time period between adjacent pulses is fixed and the duration of the pulses is varied in response to the sensed speed. Spray nozzles are driven in response to the rectangular pulse sequence.
- Certain embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein:
- FIGURE 1 is a perspective view of a spray mechanism according to the present invention, with portions of a printing mechanism depicted in phantom;
- FIGURE 2 is a side elevational view of a sprayer assembly according to the present invention;
- FIGURE 3 is a view similar to FIG. 2 displaced ninety degrees therefrom;
- FIGURE 4 is a rear end view of the sprayer assembly, with a solenoid casing thereof depicted in phantom lines;
- FIGURE 5 is a front end view of the sprayer assembly;
- FIGURE 6 is an exploded longitudinal sectional view of the sprayer assembly;
- FIGURE 7 is a fragmentary view of a nozzle section being sealingly engaged by a valve stem, with portions of the nozzle section being broken away;
- FIGURE 8 is a fragmentary longitudinal sectional view taken through the sprayer assembly when the nozzle section is closed by the valve stem;
- FIGURE 9 is a fragmentary exploded longitudinal sectional view taken through a valve section of the sprayer assembly depicting the valve stem being removed from the plunger;
- FIGURE 10 is a view similar to FIG. 8 with the valve stem in a retracted position to emit fluid flow to the nozzle;
- FIGURE 11 is a side elevational view of a prior art sprayer assembly;
- FIGURE 12 is an exploded view of the prior art sprayer assembly with portions thereof in longitudinal section;
- FIGURE 13 is a side elevational view, with portions broken away, of a prior art nozzle section;
- FIGURE 14 illustrates a rectangular pulse sequence used for actuating a spray nozzle solenoid;
- FIGURE 15 illustrates a dampening curve for correlating press speed to spray nozzle operation parameters;
- FIGURE 16 is a schematic drawing of one embodiment of a spray dampener control system in accordance with the present invention; and
- FIGURE 17 illustrates the relationships between spray nozzles, control channels, and printed pages in accordance with one feature of the present invention.
- Depicted in FIG. 1 is a portion of an offset
printing apparatus 10 comprising aplate cylinder roll 12, a water-form roll 14, a dampeningroll 16, and aspray dampener mechanism 18 according to the present invention. Thespray dampener mechanism 18 emits a pulsating spray of wetting liquid, such as water which may contain certain additives, the liquid being sprayed onto the dampener roll and from there transferred to the water-form roll. - The dampener mechanism comprising a
housing 30 upon which are mounted a plurality ofsprayer assemblies 32. Thosesprayer assemblies 32 are connected in parallel with afluid inlet conduit 34 for receiving pressurized wetting liquid by means of separate take-off lines 36 leading from theinlet conduit 34 to therespective nozzle assemblies 36. - Each
sprayer assembly 32 comprises anozzle section 38 and avalve section 40. Thenozzle section 38 comprises a generally cylindrical nozzle housing 42 (FIG. 7) which includes atransverse slot 44 at its front end. Mounted by press-fit within a center bore of thenozzle housing 42 is anozzle element 46, preferably formed of hard, wear-resistant material such as tungsten carbide. Press-fit into a rear end of the center bore is a retainingring 48, and press-fit into a center hole of thering 48 is avalve seat 50. The valve seat is of generally hollow cylindrical shape and includes atapered end 52. Thenozzle element 46 includes aslit 54 in its front end, which slit communicates with acenter passage 56 of thevalve seat 50 through acenter passage 58 in thenozzle element 46. - The
nozzle housing 42 is removably disposed in the front end of athroughbore 59 formed in a cap 60 (FIG. 6) of the type described in U.S. Patent No. 4,527,745 to Butterfield et al. Thecap 60 includesslots 62 in its outer wall for reasons to be explained hereinafter. - The valve section 40 (FIG. 6) comprises a
valve housing 70 which includes a through-bore 72, a front end of which containing aninternal thread 74. A liquid, such as a dampening solution, is supplied to thevalve housing 70 by means of aport 71 which may be threaded to receive a correspondingly threaded conduit. Removably attached to a rear end of the valve housing is ahollow post 76. Thepost 76 includes anenlarged flange 78 at its front end which fits into acounterbore 80 located at a rear end of thethroughbore 72. Aplate 82 has acentral opening 84 through which thepost 76 passes, theplate 82 being attached to therear side 86 of thevalve housing 70 by means ofscrews 88. Aresilient seal ring 90 is disposed between theplate 82 and theflange 78 to engage a flaredrear end 92 of thecounterbore 80 in order to create a fluid seal therewith. - Mounted on a rear end of the
post 76 is a conventional plug-in typesolenoid coil casing 96. That casing includes a bore 98 through which thepost 76 extends. An annularexternal groove 100 is formed at the rear end of thepost 76 to receive a retaining ring (not shown) or the like for retaining thecasing 96 on the post. A spring (not shown) may be disposed between such retaining ring and arear surface 97 of the casing to bias the casing against theplate 82. The spring would be yieldable to permit the casing to be displaced slightly away from theplate 82 in order to be rotated about the axis of thepost 76 so that the three plug-inprongs 102 could be repositioned. - The
post 76 has a hollow front end into which avalve plunger 104 is slidably disposed so as to be positioned within thesolenoid coil casing 96. The plunger is adapted to be displaced rearwardly (i.e., upwardly as viewed in FIG. 6) in response to energization of the solenoid coil containing within thecasing 96. Acoil compression spring 106 surrounds theplunger 104 and acts between theflange 78 and aflange 108 situated at a front end of theplunger 104. Theflange 108 may be formed by a split retaining ring for example. Thus, when the plunger is retracted rearwardly by the solenoid coil, thespring 106 is compressed. - Removably mounted in a front hollow end of the plunger is a
valve stem 110. Thevalve stem 110 includes arear portion 112 mounted by friction-fit within theplunger 104, and afront portion 114 of enlarged cross-section which slides within athroughbore 116 of abody member 118. The body member includesexternal threading 120 on its rear end which is screwed into the internal threading 74 of the valve housing. Thebody member 118 includes aninternal bushing 119 within which a front end of thevalve stem 110 slides. The valve stem includes a plurality oflongitudinal channels 121 in its outer periphery for conducting liquid forwardly past the bushing 119 (see FIG. 10). - Projecting from the front end of the
stem 110 is adisc 122 formed on a resilient material. Thedisc 122 is of larger diameter than the rear end of thepassage 56 formed in thevalve seat 50 and is adapted to bear sealingly thereagainst under the bias of thespring 106. It will be appreciated that thepassages stem 114, theplunger 104, and thepost 76 are aligned along a common longitudinal axis. - The
stem 110 is no longer in cross-section than thethroughbore 116 of thebody 118, whereby thestem 114 can be pulled out of the plunger 105 and completely out of thesprayer assembly 32 in a forward direction after thecap 60 andnozzle section 38 have been removed therefrom. - Instead of being mounted by friction-fit, the stem could be attached to the plunger by other quick-release connections such as a threaded connection.
- Attachment and removal of the
nozzle section 38 is effected by thecap 60 in a conventional manner. That is, theslots 62 in the cap are arranged to receive radially projectinglugs 124 formed on the outer wall of thebody 118. The side walls of theslots 62 includecam portions 126 which serve to draw the cap toward thebody 118 in response to relative rotation therebetween. This causes thefront wall 128 to be forced longitudinally against anelastic seal ring 130 positioned between thefront wall 128 and arear wall 132 of thenozzle housing 42. Counter-rotation of the cap is yieldably resisted by thus-compressedring 130. Thering 130 also creates a fluid seal once it has been compressed in that fashion. - IN OPERATION, pressurized liquid is introduced to the sprayer assembly through the
port 71. If the solenoid is de-energized, i.e., in a non-spraying mode, the valve stem is biased against thevalve seat 50 to close the nozzle element. Once the solenoid has been actuated, the plunger and stem are retracted, thereby unblocking the valve seat. Pressurized liquid is immediately ejected through thevalve outlet 54 and onto the roll. After thesealing disc 122 has become worn, removal thereof is achieved by simply unscrewing thebody member 118 and pulling thestem 110 axially from the plunger. Insertion of a new stem is achieved by reversing those steps. - The present invention offers significant advantages over a nozzle assembly previously employed in spray dampers. Such a prior
art nozzle assembly 236, depicted in FIGS. 11-13, comprises a nozzle section 238 and avalve section 240. The nozzle section 238 comprises a generallycylindrical nozzle housing 242 which includes atransverse slot 244 at its front end. Mounted by press-fit within a center bore of thenozzle housing 242 is anozzle element 246, preferably formed of a hard, wear-resistant material such as tungsten carbide. Press-fit into a rear end of the center bore is a retainingring 248. Thenozzle element 246 includes aslit 254 in its front end, which slit communicates with acenter passage 258 in thenozzle element 246. The nozzle housing 238 if removably disposed in the front end of a throughbore formed in a cap 260 (FIG. 12) of the type described in U.S. Patent No. 4,527,745 to Butterfield et al. Thecap 260 includesslots 262 in its outer wall for reasons to be explained hereinafter. - The
valve section 240 comprises avalve housing 270 which includes first and second threaded bores 271, 272 separated by apartition 273. Thebores passage 258 in thenozzle housing 242. Disposed in thevalve housing 270 perpendicularly to thebores third bore 274. Thatthird bore 274 communicates with the first andsecond bores second passages hollow post 276. Thepost 276 includes anenlarged flange 278 at its front end which fits into acounterbore 280 at a rear end of thethird bore 274. Aplate 282 has acentral opening 284 through which thepost 276 passes, theplate 282 being attached to therear side 286 of thevalve housing 270 by means ofscrews 288. Aresilient seal ring 290 is disposed between theplate 282 and theflange 278 to engage a flaredrear end 292 of thecounterbore 280 in order to create a fluid seal therewith. - Mounted on a rear end of the
post 276 is a conventional plug-in typesolenoid coil casing 296. That casing includes abore 298 through which thepost 276 extends. An annularexternal groove 300 is formed at the rear end of thepost 276 to receive a retaining ring (not shown) or the like for retaining thecasing 296 on the post. A spring (not shown) may be disposed between such retaining ring and therear side 297 of the casing to bias the casing against theplate 282. Such spring would be yieldable to permit the casing to be displaced slightly away from theplate 282 in order to be rotated about the axis of thepost 276 so that the three plug-inprongs 302 could be repositioned. - The
post 276 has a hollow front end into which avalve plunger 304 is slidably disposed so as to be positioned within thesolenoid coil casing 296. The plunger is adapted to be displaced rearwardly (i.e., to the right in FIG. 12) in response to energization of the solenoid coil contained within thecasing 296. Acoil compression spring 306 surrounds theplunger 304 and acts against theflange 278 and aflange 308 situated at a front end of theplunger 304. Theflange 308 may be formed by a split retaining ring for example. Thus, when the plunger is retracted rearwardly by the solenoid coil, thespring 308 is compressed to bias the plunger forwardly. - Disposed in a front end of the
plunger 304 is anelastic sealing member 310 which is adapted to bear against atapered seat 312 surrounding thepassage 275A under the bias of thespring 306 whenever the solenoid coil is not energized. In so doing, thepassage 275A will be closed, while thepassage 275B will remain open. - The
plunger 304 includes at least onelongitudinal channel 314 which is adapted to conduct a flow of fluid from thepassage 275B to the rear end of thehollow post 276. Such fluid would flow around an outer edge of theflange 308, though thechannel 314 and through a small hole (not shown) at the rear of thepost 276 and from there to a suitable conduit (not shown) connected to the rear end of thepost 276. - Threadedly attached to the
first bore 271 is ahollow body member 318 on which thenozzle housing 242 is to be mounted by means of thecap 260. In that regard, theslots 262 in the cap are arranged to receive radially projectinglugs 324 formed on the outer wall of thebody 318. The side walls of theslots 262 includecam portions 326 which serve to draw the cap toward thebody 318 in response to relative rotation therebetween. This causes a front wall of thebody member 318 to be forced longitudinally against an electric seal ring (not shown) positioned between the front wall and a rear wall of thenozzle housing 242. - In operation of the prior art apparatus disclosed in connection with FIGS. 11-13, pressurized fluid is delivered to the
second bore 272 and flows through thepassage 275B. If the solenoid is not energized, thevalve plunger 304 closes thepassage 275A, so that the fluid travels through thechannel 314 and out the rear end of thepost 276 to a suitable sump. If the valve is energized, causing theplunger 304 to be retracted, thepassage 275A is opened, enabling fluid to flow therethrough and from there to the nozzle element. When the plunger is retracted, a seal at the wall 330 of the plunger engages the small hole (not shown) at a rear end of the plunger to close the flow to the sump. - It will be appreciated that a sprayer assembly according to the present invention enables a worn valve stem, to be replaced by merely unscrewing the
body member 118 and pulling forwardly on thestem 110 with a force sufficiently strong to overcome the resistance of the friction-fit of thestem portion 112 within theplunger 104. A new stem can then be inserted by being pushed into the plunger. Therefore, no appreciable disassembly of the valve assembly is required. - Furthermore, by providing a push-in, friction-
fit valve seat 50 for the rear end of the nozzle element, a conventional prior art nozzle section can be converted into a nozzle section suitable for use in the present invention. Such an arrangement enables fluid flow to be terminated directly at the rear side of the nozzle section. The short distance between the valve and the spray slit 54 avoids the occurrence of pressure surges and dripping, and avoids the need to divert unused pressurized fluid to a sump when the valve is closed. Hence, there is no need to dispose of large amounts of unused liquid. - Referring now to Fig. 14, a
signal 402 includes a sequence of rectangular pulses P and may be used for controlling actuation of the spray nozzle solenoids. Briefly, when thesignal 402 is in a "HIGH" or "ON" state, current is supplied to actuate a spray nozzle solenoid. The solenoid, and thus the spray nozzle, is de-actuated when thesignal 402 is in a "LOW" or "OFF" state. The duty cycle of the pulse sequence is determined by the width of a pulse P relative to the cycle time. In other words, the duty cycle D may be determined by taking the ratio of the ON time tON and the cycle time tTOT. The cycle time tTOT is, of course, the sum of the ON time tON and the OFF time tOFF. Thus, the duty cycle D may be defined at D=tON/tTOT = tON/tON+tOFF). - In order to adjust the spray output of the spray dampener, the duty cycle of the
signal 402 may be varied. a higher duty cycle would increase the spray output from the dampener. For example, a duty cycle of 1 would mean that thesignal 402 stayed in the ON position at all times and, thus, the spray nozzles would likewise remain ON at all times. The spray nozzles would remain in an OFF state for a duty cycle of 0. In theparticular signal 402 illustrated in Fig. 14, the pulse width tON is roughly one-third of the total cycle time tTOT. Hence, the duty cycle for theillustrative signal 402 in Fig. 14 would be approximately 0.33, and a spray nozzle controlled by the signal would be ON roughly 33.3% of operating time. - The duty cycle may be varied by changing one or both of the pulse width tON on the time tOFF between adjacent pulses of the pulse sequence defined by the
signal 402. In a typical spray dampener, however, system limitations often prevent proper operation of the spray dampener beyond particular operating parameters. For instance, in systems which vary the duty cycle by varying the width of a pulse, valve and nozzle limitations prevent proper operation for pulse widths below a certain value. Thus, systems which vary ON time often suffer from poor spray patterns during periods in which spray output is low. Similarly, systems which vary the duty cycle by adjusting OFF time confront problems associated with roller drying when relatively long periods of time elapse between spray pulses, particularly during high speed press operation. The present invention, however, overcomes these difficulties. - Referring to the dampening curve of Fig. 15, the amount of dampening fluid dispensed by the spray dampener preferably has a nonlinear relationship to press speed. At press speeds below a certain speed S₀, spray dampener output may be inhibited. This situation normally would occur as the press was being brought up to printing speed. As illustrated with dampening
curve 404, between speed S₀ and speed S₁, the dampening percentage, i.e., the percentage of time during which the nozzles release dampening fluid, increases linearly with press speed at a first rate. Likewise, between press speeds S₁ and S₂, between press speeds S₂ and S₃, and above speed S₃, the dampening percentage varies linearly with press speed at different rates. If desired, the dampening curve may include a purge signal which would output when the printing press is initially brought to speed s₀. The speeds at which the dampeningcurve 404 encounters a change in slope, and the particular slopes for the individual segments of the dampening curve will depend on the printing press in which the spray dampening system is used. - In accordance with one feature of the present invention, when the press speed is below speed S₂, the pulse width tON of nozzle control pulses P is set at a predetermined value e.g., 20 microseconds, which is sufficiently long to ensure a proper spray pattern. The dampening percentage may then be varied by adjusting the time period between adjacent pulses in the pulse sequence. When the press speed is above speed S₂, the time period between adjacent pulses is set at a predetermined value, e.g., 400 microseconds, which ensures that the printing press rollers will not dry excessively between pulses of spray during high speed press operation. The dampening percentage is then varied by adjusting the pulse width of the pulses P. In this way, the present invention obtains proper spray patterns and effective operation throughout a broad range of operating conditions.
- In another embodiment of the present invention, the pulse width between speeds S₀ and S₁, may be set at a first value, for example 20 microseconds, and the pulse width between speeds S₁ and S₂, when dampening requirements are higher, may be set at a higher second value such as 30 microseconds. Similarly, the time period between adjacent pulses of the pulse sequence for press speeds between speeds S₂ and S₃ may be set at one value, for example, 500 microseconds, and at another value such as 400 microseconds for press speeds above speed S₃. Thus, finer spray control is provided by adding additional set points along the dampening
curve 404. Of course, if desired even more set points could be sprovided on the dampening curve to permit even finer spray control. - Turning now to Fig. 16, a control system in accordance with the present invention includes a
main controller 406 including a central processing unit (CPU) 408, asystem memory 410, and an input/output (I/O)device 412. Additionally, a display device (not shown) such as a liquid crystal display, a light emitting diode (LED) display, or a cathode ray tube (CRT) may be provided to permit information concerning operating parameters and the like to be conveyed to a user. Thesystem memory 410 preferably includes a non-volatile memory portion for storing one or more dampening curves. - Dampening curves may be preprogrammed into the
system memory 410 or, preferably, the dampening curves may be downloaded from a computer or from a terminal device. For this purpose, aserial communications line 414 is provided to permit thecontroller 406 to communicate with a computer. Additionally, aterminal device 416 may communicate with thecontroller 406 through acommunication line 418. Thus, the characteristics of the dampening curve, which will usually vary between presses, may be tailored to the particular application in which the spray dampener is used. - In operation, if the dampening curve information is stored in a computer, this information may be downloaded to the
controller 406 through an appropriate serial interface, such as astandard RS 422 interface. This information may be supplied toCPU 408 for storage in thesystem memory 410. Preferably, for this purpose, thesystem memory 410 includes a programmable read-only memory device (PROM). Alternatively, the dampening curve information may be supplied to theCPU 408 from aterminal device 416. Thus, if desired a user can directly store an appropriate dampening curve in thesystem memory 410. - The
CPU 408 is adapted to receive a press speed indication signal on aninput line 420. The press speed indication signal may be obtained from a standard tachometer generator, Hall effect proximity sensor or other appropriate sensor. Additionally, in modern printing presses which include a printing computer, a press speed indication signal might already be available in the press computer. In this case, the press speed indication signal may be obtained directly from the printing computer. - The
CPU 408, in response to the speed indication signal, retrieves a record from thesystem memory 410 which contains information relating to the parameters of a spray nozzle actuation control signal. For instance, the speed indication signal might be converted into a memory address value. The contents stored in thesystem memory 410 at this address might then provide information indicating a duty cycle value for the spray nozzle actuation control signal. Based upon the stored duty cycle value and the speed indication signal, the parameters of the spray nozzle actuation signal may be calculated by theCPU 408. - For example, referring again to Fig. 15, if a speed-indication signal indicating a speed S₄ is obtained by the
main controller 406, a record stored insystem memory 410 in the appropriate memory location would including a duty cycle value 0.15 corresponding to 15% dampening. Since speed S₄ is lower than speed S₂, the pulse width tON is set at a fixed value such as 20 microseconds. As discussed above, the duty cycle D may be expressed as D = tON/tON + tOFF). Solving for tOFF, we obtain tOFF=tON* (1-D)/D. Thus, tOFF + 20*(1-0.15)/0.15 = 113 microseconds. If a particular press speed value called for 6% dampening, tOFF would be 313 microseconds. - The pulse sequence parameters may similarly be calculated when the press speed value obtained by the
main controller 406 is greater than speed S₂. For example, for press speed S₅, the appropriate memory location insystem memory 410 would contain a record including a duty cycle value 0.22. Using a fixed time period of 400 microseconds between pulses, the pulse width value tON may be determined by solving the expression tON=tOFF*(D/1-D)). Thus, tON for speed S₅ would be tON = 400*(0.22/1-0.022)) = 113 microseconds. - When a press speed value corresponds to speed S₂, i.e., the speed value at which the pulse sequence changes from using a fixed pulse width to using a fixed time period between adjacent pulses, the
main controller 406 may calculate either the pulse width tON or the time period tOFF. Turning back to Fig. 16, once theCPU 408 has determined the parameters of the spray nozzle actuating pulse sequence, the I/O unit 412 is controlled to output pulse sequence to the spray bar. In a preferred manner of forming the pulse sequence from the pulse parameters, theCPU 408 utilizes count values corresponding to the pulse width and the time period between pulses. If the pulse width count value is designated CON and the count value corresponding to the time period between pulses is designed COFF, theCPU 408 may generate a rectangular pulse sequence by providing a HIGH output signal for CON clock cycles and a LOW output signal for COFF clock cycles. Count values CON and COFF may themselves be stored insystem memory 410 for retrieval by theCPU 408 in response to the press speed indication signal. - Preferably the
CPU 408 produces pulse sequences one through six which are output by I/O unit 412 on first throughsixth output lines Output lines dual channel optocoupler 434. Similarly,output lines dual channel optocoupler 436, andoutput lines 430 and 432 are connected with respective channels of adual channel optocoupler 438. The optocouplers serve to help isolate themain controller 406 from possible damage caused by transient surges and the like. -
Output line 422, after passing throughoptocoupler 434, controls the operation of a power transistor TR1. Similarly,output line 424 controls the operation of power transistor TR2;output line 426 controls the operation of power transistor TR3;output line 428 controls the operation of power transistor TR4;output line 430 controls the operation of power transistor TR5; and output line 432 controls the operation of power transistor TR6. Thus, the pulse sequences appearing on output lines 422-432 determine the operating states of power transistors TR1-TR6, respectively. In turn, the operating states of transistors TR1-TR6 determine the signals appearing on control channels 1-6, respectively. - Referring to FIG. 17,
spray bar 440 may be provided with eight spray nozzles N1-N8 arranged in a linear array.Spray bar 440 is preferably adapted to supply dampening fluid for a multipage printing press. Typically, for example, thespray bar 440 provides dampening fluid for a four page printing press. In such a case, nozzles N1 and N2 primarily control dampening ofpage 1, nozzles N3 and N4 primarily control dampening ofpage 2, nozzles N5 and N6 primarily control dampening ofpage 3, and nozzles N7 and N8 primarily control dampening ofpage 4. Of course, the spray patterns from adjacent nozzles overlap slightly. - Since end nozzles N1 and N8 are situated at the outermost portions of the linear array of nozzles, there is no dampening contribution from overlapping spray from an adjacent outer nozzle. Thus, the portions of the dampening roller adjacent the outer portions of
pages - According to one feature of the present invention, this shortcoming of prior spray dampening systems has been overcome. As indicated in FIG. 17, nozzle N1 is controlled by
channel 1; nozzle N2 is controlled bychannel 2; nozzles N3 and N4 are controlled bychannel 3; nozzles N5 and N6 are controlled bychannel 4; nozzle N7 is controlled bychannel 5; and nozzle N8 is controlled bychannel 6. In order to compensate for increased heat and reduced dampening at the outer spray nozzles, the duty cycle of the pulse sequences oncontrol channels control channel 1 may be slightly higher than the duty cycle of the pulse sequence oncontrol channel 2. Similarly, the duty cycle of the pulse sequence on control channel 8 may be slightly higher than the duty cycle of the pulse sequence on control channel 7. Preferably the duty cycle of the pulse sequences oncontrol channels 1 and 8 are functionally related to the duty cycle of the pulse sequences oncontrol channels 2 and 7, respectively. In an exemplary embodiment, the duty cycles of the pulse sequences oncontrol channels 1 and 8 are 4% higher than the duty cycles of the pulse sequences oncontrol channels 2 and 7, respectively. In other words, the duty cycle of nozzle N1 will be 1.04 times that of nozzle N2. - Since nozzles N1 and N8 each have a dedicated control channel, the different duty cycles may be accommodated. The
CPU 408 may be programmed to calculate the modified duty cycle for nozzles N1 and N8 and adjust the pulse sequences onoutput lines 422 and 432 accordingly. Dedicated power transistors TR1 and TR8 control nozzles N1 and N8 in accordance with the modified pulse sequences. - Typically, in a multipage printing operation, the printing parameters will vary from page to page. These variances in printing parameters may result in one page requiring additional (or less) dampening fluid. Accordingly, each page is provided with a separate control channel. As illustrated in FIG. 17, nozzles N3 and N4 (page 2) are operated by
channel 3. Nozzles N5 and N6 (page 3) are controlled bychannel 4. Of course, since outer nozzles N1 and N8 have dedicated control channels, nozzles N2 and N7 also have individual control channels CH2 and CH5, respectively. Again, however, it is noted that the duty cycle of the pulse sequence onchannel 1 preferably is functionally related to the duty cycle of the pulse sequence onchannel 2, and the duty cycle of the pulse sequence on channel 8 preferably is functionally related to the duty cycle of the pulse sequence on channel 7. - In order to allow greater flexibility in controlling the operation of the spray dampening device, the operating characteristics of the main controller may be varied in accordance with user instructions. Accordingly, user commands may to input to the
main controller 406 throughterminal 416. Additionally, themain controller 406 may include keypad or specific control knobs (not shown). If, for example,page 2 required increased dampening, a user could instruct theCPU 408 to increase the duty cycle of the pulse sequence onchannel 3. - Although various different aspects of the present invention have been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications and substitutions not specifically described may be made without departing from the scope of the invention as defined in the appended claims.
Claims (22)
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14532388A | 1988-01-19 | 1988-01-19 | |
US145327 | 1988-01-19 | ||
US145323 | 1988-01-19 | ||
US07/145,327 US4873925A (en) | 1988-01-19 | 1988-01-19 | Spray nozzle and valve assembly |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0325381A2 true EP0325381A2 (en) | 1989-07-26 |
EP0325381A3 EP0325381A3 (en) | 1990-11-07 |
EP0325381B1 EP0325381B1 (en) | 1995-10-04 |
Family
ID=26842856
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890300326 Expired - Lifetime EP0325381B1 (en) | 1988-01-19 | 1989-01-13 | A control system for operating a spray dampening system |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0325381B1 (en) |
JP (1) | JP2746975B2 (en) |
AU (1) | AU2856289A (en) |
CA (1) | CA1313388C (en) |
DE (1) | DE68924433T2 (en) |
NZ (1) | NZ227640A (en) |
Cited By (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0570676A1 (en) * | 1992-05-16 | 1993-11-24 | Grafotec Kotterer Gmbh | Device for cleaning a cylinder |
EP0704299A1 (en) * | 1994-09-19 | 1996-04-03 | Rockwell International Corporation | Spray bar assembly for a printing press |
EP0726147A1 (en) * | 1995-01-20 | 1996-08-14 | MAN Roland Druckmaschinen AG | Controller for the blanket washing system of a rotary offset printing machine with several units |
EP0736383A1 (en) * | 1995-04-03 | 1996-10-09 | Tokyo Kikai Seisakusho Ltd. | Dampening systems in offset printers |
WO1998018560A1 (en) * | 1996-10-25 | 1998-05-07 | Machinefabriek Gebr. Douven B.V. | Spray nozzle, and also spray boom provided therewith |
WO1999048693A1 (en) * | 1998-03-23 | 1999-09-30 | Goss Graphic Systems, Inc. | Method and apparatus for controlling a dampener of a lithographic printing press |
WO2000032397A1 (en) * | 1998-12-02 | 2000-06-08 | Baldwin Jimek Ab | A method and device at a spraying ramp for a printing press |
EP1033245A1 (en) * | 1999-03-01 | 2000-09-06 | Heidelberger Druckmaschinen Aktiengesellschaft | Spraying damping unit with high effective spraying frequency |
EP1321571A2 (en) * | 2001-12-11 | 2003-06-25 | Voith Paper Patent GmbH | Method and device for spraying a moving fibrous web |
DE10213959A1 (en) * | 2002-03-28 | 2003-10-09 | Baldwin Germany Gmbh | Moisturizing water circuit sector for offset printing press has cleaning device including cleaning tank, extraction device and filter housing |
DE10213109A1 (en) * | 2002-03-23 | 2003-10-09 | Baldwin Germany Gmbh | Printing machine spray device for an offset printing machine comprises a heat-exchanger path along which supplied fountain water and removed fountain water are guided together in heat exchange |
WO2005065948A1 (en) * | 2004-01-12 | 2005-07-21 | Baldwin Jimek Ab | An electronically controlled valve with a sensing mean for providing an output signal |
EP1780010A1 (en) | 2005-10-14 | 2007-05-02 | Technotrans AG | Valve assembly specially for dampening units of printing machines |
WO2007123660A2 (en) * | 2006-03-31 | 2007-11-01 | Technotrans America, Inc. | A spray dampening valve having mechanical accuracy and long-term stability for use in an offset printing process |
DE102006033789B4 (en) * | 2006-07-19 | 2008-10-30 | Baldwin Germany Gmbh | Dampening water supply device for at least one spray dampening unit of an offset printing machine |
DE102006033790B4 (en) * | 2006-07-19 | 2008-11-13 | Baldwin Germany Gmbh | Dampening water supply device for at least one spray dampening unit of an offset printing machine |
CN102310630A (en) * | 2010-06-30 | 2012-01-11 | 海德堡印刷机械股份公司 | Be used for jet rod at the printing machine atomizing of liquids |
CN114146852A (en) * | 2021-11-22 | 2022-03-08 | 江苏迎凯涂装设备有限公司 | Spraying pressure structure with automatic circulating rotary spraying function |
US11759811B2 (en) | 2018-06-29 | 2023-09-19 | Baldwin Jimek Ab | Spray application system with memory and controller for controlling spray bar |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FI108061B (en) * | 1995-10-05 | 2001-11-15 | Metso Paper Inc | Method for coating a paper or cardboard web |
DE19838020A1 (en) * | 1997-09-15 | 1999-03-18 | Roland Man Druckmasch | Unit for applying moisture to rotary printing machine |
DE19946479A1 (en) * | 1999-09-28 | 2001-03-29 | Voith Paper Patent Gmbh | Method and device for spraying a moving fibrous web |
JP3664439B2 (en) | 2002-07-29 | 2005-06-29 | 株式会社東京機械製作所 | Fountain spray equipment |
CN113399189B (en) * | 2021-05-10 | 2022-11-29 | 湖南风河竹木科技股份有限公司 | Sheet brushing glue device in bamboo wood processing process |
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DE2031960A1 (en) * | 1970-06-27 | 1971-12-30 | ||
FR1604741A (en) * | 1967-12-27 | 1972-01-24 | ||
DE2044423A1 (en) * | 1970-09-08 | 1972-03-16 | Ibema Sobotta U Rehme Gmbh & C | Paint sprayer, especially for marking faults when testing materials |
EP0104787A1 (en) * | 1982-09-07 | 1984-04-04 | Greatbatch Enterprises, Inc. | Low power electromagnetic valve |
DE3608124A1 (en) * | 1985-04-22 | 1986-10-23 | VEB Kombinat Polygraph "Werner Lamberz" Leipzig, DDR 7050 Leipzig | Two-component nozzle for spraying damping units in printing machines |
US4649818A (en) * | 1985-07-22 | 1987-03-17 | Ryco Graphic Manufacturing, Inc. | Variable frequency pulsed spray dampening system |
US4708058A (en) * | 1985-10-10 | 1987-11-24 | Smith Rpm Corporation | Water pulse spray dampening system and method for printing presses |
-
1989
- 1989-01-11 CA CA000587942A patent/CA1313388C/en not_active Expired - Fee Related
- 1989-01-13 DE DE1989624433 patent/DE68924433T2/en not_active Expired - Fee Related
- 1989-01-13 EP EP19890300326 patent/EP0325381B1/en not_active Expired - Lifetime
- 1989-01-17 NZ NZ22764089A patent/NZ227640A/en unknown
- 1989-01-18 JP JP1009635A patent/JP2746975B2/en not_active Expired - Fee Related
- 1989-01-18 AU AU28562/89A patent/AU2856289A/en not_active Abandoned
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FR1604741A (en) * | 1967-12-27 | 1972-01-24 | ||
DE2031960A1 (en) * | 1970-06-27 | 1971-12-30 | ||
DE2044423A1 (en) * | 1970-09-08 | 1972-03-16 | Ibema Sobotta U Rehme Gmbh & C | Paint sprayer, especially for marking faults when testing materials |
EP0104787A1 (en) * | 1982-09-07 | 1984-04-04 | Greatbatch Enterprises, Inc. | Low power electromagnetic valve |
DE3608124A1 (en) * | 1985-04-22 | 1986-10-23 | VEB Kombinat Polygraph "Werner Lamberz" Leipzig, DDR 7050 Leipzig | Two-component nozzle for spraying damping units in printing machines |
US4649818A (en) * | 1985-07-22 | 1987-03-17 | Ryco Graphic Manufacturing, Inc. | Variable frequency pulsed spray dampening system |
US4708058A (en) * | 1985-10-10 | 1987-11-24 | Smith Rpm Corporation | Water pulse spray dampening system and method for printing presses |
Cited By (25)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0570676A1 (en) * | 1992-05-16 | 1993-11-24 | Grafotec Kotterer Gmbh | Device for cleaning a cylinder |
EP0704299A1 (en) * | 1994-09-19 | 1996-04-03 | Rockwell International Corporation | Spray bar assembly for a printing press |
EP0726147A1 (en) * | 1995-01-20 | 1996-08-14 | MAN Roland Druckmaschinen AG | Controller for the blanket washing system of a rotary offset printing machine with several units |
EP0736383A1 (en) * | 1995-04-03 | 1996-10-09 | Tokyo Kikai Seisakusho Ltd. | Dampening systems in offset printers |
WO1998018560A1 (en) * | 1996-10-25 | 1998-05-07 | Machinefabriek Gebr. Douven B.V. | Spray nozzle, and also spray boom provided therewith |
WO1999048693A1 (en) * | 1998-03-23 | 1999-09-30 | Goss Graphic Systems, Inc. | Method and apparatus for controlling a dampener of a lithographic printing press |
WO2000032397A1 (en) * | 1998-12-02 | 2000-06-08 | Baldwin Jimek Ab | A method and device at a spraying ramp for a printing press |
AU751026B2 (en) * | 1998-12-02 | 2002-08-08 | Baldwin Jimek Ab | A method and device at a spraying ramp for a printing press |
EP1033245A1 (en) * | 1999-03-01 | 2000-09-06 | Heidelberger Druckmaschinen Aktiengesellschaft | Spraying damping unit with high effective spraying frequency |
US6327974B1 (en) | 1999-03-01 | 2001-12-11 | Heidelberger Druckmaschinen Ag | Spray dampening device having high effective spray frequency and method of using |
EP1321571A2 (en) * | 2001-12-11 | 2003-06-25 | Voith Paper Patent GmbH | Method and device for spraying a moving fibrous web |
EP1321571A3 (en) * | 2001-12-11 | 2004-02-04 | Voith Paper Patent GmbH | Method and device for spraying a moving fibrous web |
DE10213109A1 (en) * | 2002-03-23 | 2003-10-09 | Baldwin Germany Gmbh | Printing machine spray device for an offset printing machine comprises a heat-exchanger path along which supplied fountain water and removed fountain water are guided together in heat exchange |
DE10213109B4 (en) * | 2002-03-23 | 2005-02-17 | Baldwin Germany Gmbh | Printing machine spraying device |
DE10213959A1 (en) * | 2002-03-28 | 2003-10-09 | Baldwin Germany Gmbh | Moisturizing water circuit sector for offset printing press has cleaning device including cleaning tank, extraction device and filter housing |
WO2005065948A1 (en) * | 2004-01-12 | 2005-07-21 | Baldwin Jimek Ab | An electronically controlled valve with a sensing mean for providing an output signal |
EP1780010A1 (en) | 2005-10-14 | 2007-05-02 | Technotrans AG | Valve assembly specially for dampening units of printing machines |
WO2007123660A2 (en) * | 2006-03-31 | 2007-11-01 | Technotrans America, Inc. | A spray dampening valve having mechanical accuracy and long-term stability for use in an offset printing process |
WO2007123660A3 (en) * | 2006-03-31 | 2007-12-27 | Technotrans America Inc | A spray dampening valve having mechanical accuracy and long-term stability for use in an offset printing process |
DE102006033789B4 (en) * | 2006-07-19 | 2008-10-30 | Baldwin Germany Gmbh | Dampening water supply device for at least one spray dampening unit of an offset printing machine |
DE102006033790B4 (en) * | 2006-07-19 | 2008-11-13 | Baldwin Germany Gmbh | Dampening water supply device for at least one spray dampening unit of an offset printing machine |
CN102310630A (en) * | 2010-06-30 | 2012-01-11 | 海德堡印刷机械股份公司 | Be used for jet rod at the printing machine atomizing of liquids |
CN102310630B (en) * | 2010-06-30 | 2015-04-22 | 海德堡印刷机械股份公司 | Spraying rod for spraying liquid in printing machine |
US11759811B2 (en) | 2018-06-29 | 2023-09-19 | Baldwin Jimek Ab | Spray application system with memory and controller for controlling spray bar |
CN114146852A (en) * | 2021-11-22 | 2022-03-08 | 江苏迎凯涂装设备有限公司 | Spraying pressure structure with automatic circulating rotary spraying function |
Also Published As
Publication number | Publication date |
---|---|
JP2746975B2 (en) | 1998-05-06 |
EP0325381A3 (en) | 1990-11-07 |
DE68924433T2 (en) | 1996-05-09 |
JPH026863A (en) | 1990-01-11 |
AU2856289A (en) | 1989-07-20 |
NZ227640A (en) | 1991-02-26 |
CA1313388C (en) | 1993-02-02 |
DE68924433D1 (en) | 1995-11-09 |
EP0325381B1 (en) | 1995-10-04 |
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