The present invention relates to a new and improved hammerboard for a drop forge press. More particularly the invention concerns a laminated plywood hammerboard comprising a series of very thin plies of hard, high density wood veneer with the grain of each ply of veneer running along its length, each ply having nonsawed peeled opposed surfaces providing glue surfaces thereon. The plies of the hammerboard are of a relatively thin construction and glue is disposed on the surfaces to secure each of the plies together to provide a new and improved manner.
Drop hammerboards are used in a common type of drop hammer forge. They are widely used in the forging industry throughout the world with heavy concentrations in the upper Midwest.
Specifically, a drop hammer forge has a stationary die and a moving die. This moving die is fastened onto a large weight (hammer) which is pulled up and then falls free onto the stationary die. One end of the drop hammerboard is clamped onto the hammer and the other end extends straight up between two rollers. These rollers clamp the board and pull the hammer assembly up. The rollers then release and allow the hammer to fall. There is also a brake to hold the board and hammer in the up position.
Present construction of boards: Boards are now made of hard maple lumber. Either one piece or several pieces laminated together. One variation is a layer of leather glued in. The approximate sizes used range from 11/4" to 2 1/16" thick, 7' to 15' long, and 3" to 12" wide.
Problems with present boards: The boards are subject to extreme shocks when the hammer hits bottom. They frequently break before they are worn out with estimates of premature breakage running upwards of 50%. Another problem is that the rollers wear the boards out, with the time dependent on the particular shape being forged. These problems lead to frequent shut downs to replace broken and worn boards and some danger to personnel with the flying pieces.
Our solution is to manufacture these boards from hard wood veneer having the grain oriented so as to extend the length of the board in one preferred embodiment. We start by cutting hard maple logs into veneer 1/32" to 3/16" thick and then we glue this veneer back together into panels of the proper size for drop hammerboards. This process allows us to engineer the boards to reduce or eliminate the breakage and improve the wearing properties.
In hammerboards, the laminated lumber construction has been known for many years. The newly developed preferred hard wood veneer type laminated hammerboard as herein disclosed has been found to work in a much improved manner over anything previously known to have been used and the life of such a board has been found to greatly exceed the useful life of other hammerboards used just before this invention. Laminated lumber hammerboards are formed from sawed layers as distinguished from the peeled layers of veneer used on our new board.
In view of the improved characteristics of the herein disclosed hard wood veneer type laminated hammerboard, an important object of this invention is to provide a hammerboard construction that has a life expectancy far exceeding any other known hammerboard, and to reduce down time for the user.
Another object of this invention is to provide a hammerboard construction that can be manufactured at least in part with known manufacturing procedures, and in such a way that the hammerboards can be produced on a production basis to satisfy the needs of the marketplace.
Another object of this invention is to provide a new and improved method of manufacturing hammerboards having peeled layers.
Still a further object of this invention is to provide a new and improved laminated plywood hammerboard comprised of a series of very thin hard, high density wood material with the grain of each ply of the veneer running along the length of the hammerboard and with glue being disposed on the surfaces provided in peeled surfaces of each ply, thus providing a tough bond and a hammerboard that has a life expectancy far exceeding any previously known hammerboards.
According to an important feature of this invention, we have provided a laminated plywood hammerboard for a drop forge press comprised of a series of plies of hard, high density wood maple veneer with the grain of at least most of said plies running along its length and with each of the plies having a thickness in the range of 1/32" to 3/16", and glue being deposited between the plies securing the plies together and providing a relatively large number of hard glue surfaces enhancing the wearability of the board.
Other features of the present invention relate to providing different types of hammerboards, at least one of which has a useful life of 472 hours by first using the board with one end attached to a hammer on a drop hammer forge and then by rotating the board 180 degrees and reattaching the opposite end of the board to the hammer for another period of use.
Still, other features of this invention relate to providing a hammerboard where most of the plies have a grain structure such that the grain structure runs the length of the hammerboard, but also where a selected number of the plies has a cross-grain structure at right angles to the longitudinally extending grain of the other plies to provide a tougher hammerboard construction that can hold up for longer periods of use.
Yet, another feature of this invention is to provide a hammerboard construction comprised of a series of plies where the plies have opposite edges so disposed that rollers on the drop forge press can engage directly against the opposite edges of the plies so that the useful life of the hammerboard can be prolonged as long as possible.