Abrading – Frame or mount – Portable abrader
Reexamination Certificate
1999-01-25
2001-03-27
Ostrager, Allen M. (Department: 3725)
Abrading
Frame or mount
Portable abrader
C451S359000, C451S345000
Reexamination Certificate
active
06206771
ABSTRACT:
BACKGROUND OF THE INVENTION
Orbital abrading machines are well-known and generally comprise a portable, manually manipulatable housing, a motor supported by the housing and having or being coupled to a drive shaft driven for rotation about a first axis, and an assembly for mounting a pad for abrading a work surface for orbital movement about the first axis. In a random orbital abrading machine, the assembly serves to additionally mount the pad for free rotational movement about a second axis, which is disposed parallel to the first axis.
The assembly typically includes a head portion coupled for driven rotation with the drive shaft about the first axis and defining a mounting recess having an axis arranged coincident with the second axis, a bearing supported within the mounting recess, and means for connecting the pad to the bearing for rotation about the second axis.
Orbital machines by nature are subject to dynamic unbalance and require the inclusion of a counterbalance system to reduce vibration to an acceptance level. The typical design approach has been to account only for the unbalance, which is created by the mass centers of the pad and portions of the assembly not disposed concentric to the first axis, by the addition of balancing masses to the housing. This approach can create a machine that is balanced, that is, has acceptably low vibration levels, while the machine is running at free speed in an unloaded condition. However, once the machine is loaded, as a result of placing the pad in abrading engagement with a work surface, additional forces are introduced and the machine becomes unbalanced and this unbalance is detected by the operator in the form of vibration. This is undesirable and in severe cases, may lead to vibration induced injuries such as carpal tunnel syndrome and white finger.
The counterbalance system referred to above, which may be used in the design of both orbital and random orbital machines, is described for example in Chapter 12 of Mechanisms and Dynamics of Machinery, Third Edition, by Hamilton H. Mabie and Fred W. Ocvirk, published by John Wiley & Sons.
Another approach is that adopted for the Atlas Copco Turbo Grinder GTG40, which uses an SKF Nova AB auto-balancing unit to reduce vibration under various loading conditions. This unit features the use of a plurality of ball bearings, which are arranged within an annular raceway and free to move therewithin as required to reducing vibrations.
SUMMARY OF THE INVENTION
It is known that both orbital and random orbital abrading machines, which include for example, sanding, grinding and buffing machines, that have been balanced to minimize vibration under no load operating conditions, may be subjected to unacceptable levels of vibration under actual working conditions.
The present invention relates to an improved, orbital abrading machine, and more particularly to an improved random orbital buffer, which may be counterbalanced in such a manner as to minimize vibrations under actual working conditions.
The present invention is based on the realization that known balancing techniques, which may be employed to achieve proper balancing under unloaded conditions, do not take into consideration forces at work, during actual working conditions, which oftentimes result in a properly balanced machine becoming unbalanced to an unacceptable degree during use. More particularly, the present invention is directed towards a counterbalancing system adapt to minimize vibration of a orbital abrading machine under determined operating conditions.
REFERENCES:
patent: Re. 29247 (1977-06-01), Kilstrom et al.
patent: 3866489 (1975-02-01), Kimmelaar
patent: 4660329 (1987-04-01), Hutchins
patent: 4729194 (1988-03-01), Maier et al.
patent: 4811522 (1989-03-01), Gill, Jr.
patent: 4854085 (1989-08-01), Huber
patent: 5040340 (1991-08-01), Bischof et al.
patent: 6007412 (1999-12-01), Hutchins
Hamilton H. Mabie & Fred W. Ocvirk, “Mechanisms and Dynamics of Machinery”, Third Edition, Chapter 12, pp. 490-497.
SKF, “Auto-Balancing”, 4597E, 1997, pp. 1-5, 7-8.
Jonas Nlisagard & Helene Richmond, “Auto-Balancing Cuts Vibration By Half”, Jan. 1995, pp. 27-30.
Dynabrade, Inc.
Hong William
Ostrager Allen M.
Simpson, Simpson & Snyder, L.L.P.
LandOfFree
Balancer for orbital abrading machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Balancer for orbital abrading machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Balancer for orbital abrading machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2471335