NOTE 1—This test method is similar to SAE J The values stated in metric units are to be regarded as the standard. The English units. 人阅读|次下载. SAE J 石击试验标准(免费版)_机械/仪表_工程 科技_专业资料。SAE J dingharbasuppprom.gq This SAE Recommended Practice covers a laboratory procedure for testing and evaluating the resistance of surface coating to chipping by gravel impact. The test is designed to reproduce the effect of gravel or other media striking exposed paint or coated surfaces of an automobile.
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Scope: The Gravelometer is designed to evaluate the resistance of surface coatings (paint, clear coats, metallic plating, etc.) to chipping caused by the impacts of. SAE J Direct Inland,45°South. Good (after 1 year) SAE J h . 65°C- cycle minUV+ Resistance. SAE J L of graded. NOV Issued Revised Superseding J DEC Test for Chip Resistance of Surface Coatings 1. Scope—This SAE Recommended.
Still another advantage of the present invention is that a three-dimensional specimen target chamber is easily and selectively connectable to any of the target chambers as needed for testing three-dimensional specimens in accordance with any testing standard. Yet another advantage of the present invention is that a wide variety of blast media such as gravel, split shot, buckshot, sand, or MDOT 25A, is able to be used for testing procedures. A further advantage of the present invention is that it is more easily and less expensively repaired or calibrated.
Still other benefits and advantages of the invention will become readily apparent to those skilled in the art upon reading and understanding the following detailed specification. The gravelometer includes a base unit 30 to which modular components are selectively connected as is described in detail below. The base unit 30 comprises a source of compressed air or other gas which may be a receiver tank 40 connected to al shop air supply or another source. The tank 40 is supported above a shop floor by a combination of wheels 42 and feet 44 that facilitate movement of the gravelometer 20 as desired.
The base unit 30 also includes a main frame 46 connected to the upper region of the tank A media gun frame or mount 50 is connected to the main frame or formed as a one-piece construction therewith and includes a bore 52 or other means for releasably receiving a media gun 54 and operatively supporting the gun so that a media inlet 56 of the gun is upwardly oriented and so that the gun barrel media outlet 57 extends through the gun mount As shown herein, the media inlet 56 of the gun 54 is connected to an elongated conduit An open upper end of the conduit 58 is in communication with an automatic media supply system The media supply system 60 receives and retains a supply of gravel or other blast media in a hopper 62 and includes means for dispensing the media from the hopper into the, gun inlet conduit 58 in a controlled manner.
As shown herein, the dispensing means comprises a vibratory feeder assembly 64 supported by the frame 50, although any other suitable feeding means may be employed. Alternatively, an operator of the apparatus 20 is able to manually control the flow of media into the gun inlet The apparatus 20 includes means for releasably engaging the gun 54 and securing the gun in the operative position without requiring use of wrenches, screwdrivers, or like tools—i.
For example, as shown herein, first and second toggle clamps 72,74 FIG. Alternatively, the gun may be operatively secured to the frame 50 via means such as a collar assembly, a threaded or key-like connection, bolts, pins, or other fasteners, or any other suitable means that allows the gun 54 to be quickly and easily affixed to and separated from the frame As is shown in FIGS. The nozzle 76 is connected to the compressed air supply 40 using suitable conduit and one or more valves that allow the selective flow of compressed air to the gun nozzle With reference again to FIGS.
In FIGS. The target chamber 90 defines an enclosure which shields a test specimen and prevents the escape of the blasting media after it impacts a test specimen. The target chamber 90 includes a media inlet 92, a media outlet 94, and a specimen window In this manner, media propelled into the target chamber 90 along the horizontal projection path impinges upon the test sample but is contained within the target chamber. The spent media falls through the media outlet 94 into a media reclaim chamber As noted, the subject multi-test gravelometer 20 comprises means for selectively, operatively, and releasably connecting the modular target chamber 90 to the base unit 30 so that any one of a plurality of different modular target chambers may be connected to the base unit as desired to comply with a particular testing standard in an easy and convenient manner without aid of tools.
Also, for purposes of facilitating releasable connection of a target chamber 90, it is preferred that the frame 50 include one or more locator pins FIGS. A target chamber safety switch is connected to the control system 80 and senses the proper connection of the target chamber 90 to the frame In the event the chamber 90 is not properly connected to the frame, the control system will not allow operation of the apparatus The parts of the modular chambers ,, relative to the modular chamber 90 are indicated with like reference numerals that are , , and units greater, respectively, than corresponding parts of the target chamber Each modular target chamber 90,,, also includes a vent opening formed therethrough for the exhaustion of the compressed lair that propels the blast media.
A dust filter FIG. As shown herein, the filter is secured in the opening through use of a frame which slidably receives the filter.
Other filter securement means may be used as desired. Rather than securing a two-dimensional panel or other specimen in the window 96,, the window is left open and a three-dimensional specimen, such as a spring, wheel cover, or the like, is positioned in the three-dimensional specimen target chamber The specimen is placed in the chamber through a hinged access door The chamber preferably also includes an adjustable clamping bar movable toward and away from the window or other like means for fixedly securing a specimen is a desired location in line with the window The invention has been described with reference to preferred embodiments.
Obviously, modifications and alterations will occur to to hers upon a reading and understanding of the preceding specification. It is intended that the invention be construed as including all such modifications and alterations insofar as they fall within the scope of the appended claims and equivalents thereof. Claims 10 Having thus described the preferred embodiments, the invention is claimed to be: 1. The multi-test gravelometer as set forth in claim 1 further comprising: a media supply system connected to said frame, said media supply system including a media hopper for containing a supply of testing media and a media feeder for communicating testing media from the hopper to the medial inlet of the associated media gun secured to said frame.
The multi-test gravelometer as set forth in claim 2 wherein said media feeder comprises a vibratory feeder. The multi-test gravelometer as set forth in claim 1 further comprising: at least one clamp connected to said frame and adapted for selectively engaging a radially enlarged flange portion of said associated media gun, said at least one clamp, when closed, fixedly securing said flange in abutment with said frame.
The multi-test gravelometer as set forth in claim 1 further comprising: a plurality of locator pins extending from said frame for engagement with mating apertures of each of said at least two target chambers; and, a plurality of retaining clips for selectively and releasably interconnecting each of said at least two target chambers to said frame.
The multi-test gravelometer as set forth in claim 1 , wherein said at least two target chambers comprise: a two-dimensional specimen target chamber selectively, operatively, and releasably secured to said frame; and, a three-dimensional specimen target chamber selectively, operatively, and releasably connected to said two-dimensional specimen target chamber, said three-dimensional specimen chamber adapted to receive and support a three-dimensional target specimen for impingement by media traveling on said target path.
A multi-test gravelometer for performing coating testing operations in accordance with at least two different standards as desired by a user, said gravelometer comprising: a frame adapted to receive and selectively releasably retain, individually, both an SAE compliant media gun and a VDA compliant media gun in an operative position wherein a media inlet of said selectively received and retained gun is positioned to receive testing media and a media outlet of said associated gun is positioned to project testing media toward a testing target; a compressed air supply adapted for communication with an air inlet of said associated gun; and, means for releasably securing any one of a plurality of different two-dimensional specimen target chambers to said frame in an operative position so that the media outlet of an associated gun is directed into and enclosed by an interior portion of an operatively secured target chamber in line with a target specimen support region thereof.
Available from Society of Automotive Engineers, Inc. NOTE— Values in chart are specific to the standard gravel testing protocol. Different specifications may be necessary for other media types.
If the answer to any of the following questions is NO, discontinue testing until the problem has been corrected. The gravel will pass through It is important to note that mesh screen is not a substitute for space screen. The gravelometer has 9. Because the gravel tends to blunt or fragment after repeated impacts, it should be changed at a regular frequency.
For testers that are operated on a weekly basis, 2 pints of gravel shall be replaced with fresh gravel each month. For testers that are operated on less frequent basis, 2 pints of gravel shall be replaced with fresh gravel at least every 6 months.
Gravel must be washed prior to initial use. Other media may be used as agreed upon by contractual parties. NOTE— Pint measurements refer to a 1 pint container full to the top. Other tape may be used as agreed upon by contractual parties.
NOTE— The adhesion strength of the tape use makes a significant impact on how much separated paint is removed. Tests conducted at different temperatures will employ the following: METHOD A—A cold room or chamber in which the gravelometer and test panels are maintained at the specified temperature of testing.
For freezers that employ a defrosting mechanism, document the method of defrosting and any temperature changes. Transparent Grid—A chip counting aid constructed of transparent plastic approximately 3.
Chipping Rating Standards—A photographic transparency, depicting the size and shape of each chip. See Figure 3 for representation of this transparency.
The number of replicates will be agreed upon between contractual parties. The test specimens are typically flat and Any deviations in these parameters may produce misleading test results. For profiled test specimens, or nonstandard test specimens, limits for uniform thickness, uniform backing, and uniform specimen holders must be determined and agreed upon by contractual parties.
Uniformity of film thickness is extremely important, and each component of the system should be controlled as uniformly as possible. In the conditioning environment, proper heat transfer can be facilitated by separating the test specimens so that the conditioned air can circulate freely about the specimen. During exposure of multiple specimens, no more than 10 pt of gravel shall be allowed to collect on the sizing screen.
Once 10 pt have collected on the screen, scrape the gravel across the screen so that the small rocks will fall beneath the screen. Remove the gravel that remains on top of the screen from the gravelometer for re-use. Remove and discard any stones that have lodged in the screen. For older cabinet type gravelometers, keep lid to gravel chamber on the gravelometer closed during this operation as safety precaution.
Other air pressures can be used as agreed upon by contractual parties. After the air pressure is adjusted, shut off air valve, and open the lid to the specimen chamber. Place one test specimen conditioned at the desired test temperature in the panel holder with the coated side facing the gravel projecting mechanism.
Mount the specimen as tightly as possible so as not to affect the angle of the panel orientation or allow movement during the test.
The specimen holder shall have an edge-supported backer plate. Other specimen mounting fixtures may be used as agreed upon by contractual parties. Close lid to panel chamber. Open the gravel feed door and pour gravel from the one pint container obtained from step 5. Do not allow gravel to fall into the nozzle entrance.
Open the air valve to allow the air to project the gravel at the sample. NOTE 1—The gravel hopper must empty within 7 to 10 s. If gravel remains in the hopper after 10 s, stop the test and investigate the cause. The operator may not touch the gravel during the test or otherwise physically help the gravel into the funnel. NOTE 2—It is important to note that the vibrator may become frozen when the chamber is installed in a cold room or freezer. If the vibrator is frozen, discontinue the test until the vibrator has thawed and is operating correctly.
NOTE 3—Shut off air valve, open lid to specimen chamber, and remove the test specimen. Clamp to close the specimen holder. Pour gravel from the one pint container obtained from step 5. Set the Test Timer. There are two ways to operate a test on these units.
A Timed Test is a test that shuts off the machine after the preset amount of time has passed. A Manual Test requires the operator to shut off the machine after the desired amount of time has passed.
Timed Test a. Make sure the control switch is set to STOP. Set the Test Timer to the desired test time. Turn the main power switch to ON. The manual test requires the operator to manually stop the test.
Once started, it will not stop by itself. Make sure the control switch is on OFF. After the desired amount of time has passed, flip the control switch to OFF.