US 4,766,790 A · Band saw apparatus and method

Abstract

Band saw apparatus is disclosed which includes a drive assembly formed for support and guided movement of a saw blade for cutting of a workpiece, an endless band saw blade mounted to the drive assembly, and reciprocation apparatus formed for reciprocation of the blade toward and away away from the workpiece to enable see-sawing of the blade and variation of the force per unit area of the cutting edge of the blade on the workpiece while maintaining the same total force on the blade. To enhance toward and efficiency of cutting the blade drive assembly is mounted to the remainder of the saw to be substantially free to rebound or move away from the workpiece during reciprocation to avoid digging in or shearing off of the blade teeth and to permit close spacing of the blade guides next to the workpiece. The saw includes a control circuit for controlling the rate of movement of the saw arm away from and toward the workpiece to enable timing of saw arm rebound to blade displacement. The blade guides are reciprocated by the fluid piston-cylinder assemblies in synchronism or out-of-phase to vary the amplitude, frequency, speed and dwell during displacement independently of blade speed and at two locations along a length of the blade so as to produce see-sawing oscillation as well as simple reciprocation. The blade guide assemblies are provided with displacement means to permit guide assembly adjustment during cutting to maintain the guide assemblies in close proximity to the workpiece. Alternative blade displacement assembly constructions and a method for cutting workpieces employing the apparatus also are disclosed. The method includes variation of the feed rate of the saw blade down through the workpiece as a function of the width of the workpiece.

Claims17

Dependent claims

A method of cutting a workpiece with a band saw or the like including the steps of:

moving a cutting stretch of a saw blade across said workpiece to effect cutting, and simultaneously varying the force per unit area of said saw blade against said workpiece, wherein the improvement in said method of cutting is comprised of:
said varying step is accomplished by periodically reducing and thereafter increasing the area of said workpiece engaged by said saw blade by:
(i) substantially simultaneously displacing said saw blade in opposite directions at two spaced-apart locations along said saw blade by balde guide assemblies having displaceable blade engaging portions to tilt said cutting stretch about said workpiece in a first direction and to reduce said area;
(ii) thereafter maintaining said cutting stretch tilted in said first direction while moving said saw blade across said workpiece to cut said workpiece and thereby increase said area;
(iii) thereafter substantially simultaneously displacing said saw blade by said blade engaging portions in opposite directions at two spaced-apart locations along said saw blade to tilt said cutting stretch about said workpiece in a second direction opposite said first direction and to reduce said area;
and
(iv) thereafter maintaining said cutting stretch tilted in said second direction while moving said saw blade across said workpiece to cut said workpiece and thereby increase said area.

4 more elements

A band saw including a frame, carriage means movably mounted to said frame and biased for movement toward a workpiece to be cut, an endless saw blade movably mounted to said carriage means and having a cutting stretch oriented for cutting of said workpiece upon movement of said carriage means toward said workpiece and advancement of said saw blade, and adjustable feed control means including a first fluid piston-cylinder assembly coupled between said carriage means and said frame and formed to control the rate of movement of said carriage means toward said workpiece, wherein the improvement in said band saw comprises:

cutting enhancement means associated with said saw and formed and operable to cause at least one of periodic reduction of the area of said workpiece being cut by said saw blade and periodic increase of the total force applied by said saw blade against said workpiece;
adjustable force control means including a second fluid piston-cylinder assembly coupled between said carriage means and said frame and formed to enable selection and control of the amount of support force resisting movement of said carriage means toward said workpiece substantially independently of said first fluid piston-cylinder assembly and substantially independently of said cutting enhancement means;
and
said adjustable feed control means being formed for selective substantial disengagement of said first fluid piston-cylinder assembly from control of the rate of movement of said carriage means to enable regulation of movement of said carriage means toward said workpiece primarily by adjustment of said second fluid piston-cylinder assembly during cutting when said cutting enhancement means is in operation.

1 more element

A method of cutting a workpiece with a band saw assembly, said saw assembly having a movable carriage biased for movement toward said workpiece, a band saw blade movably mounted to said carriage to effect cutting, feed control means coupled to said carriage and formed to control the rate of movement of said carriage and saw blade toward said workpiece, force control means coupled to said carriage and formed to apply a controlled supporting force to said carriage to control of the minimum force applied by said carriage to said band saw blade during cutting, and cutting enhancement means associated with said saw assembly and formed to produce periodic increases in the cutting pressure of the saw blade teeth engaging said workpiece independently of said force control means, wherein said method is comprised of the steps of:

(a) advancing said saw blade across said workpiece while feeding said saw blade into said workpiece to effect cutting of said workpiece;
(b) during said advancing and feeding step, enhancing the rate of cutting said workpiece by periodically increasing the cutting pressure applied by the teeth engaging said workpiece by said cutting enhancement means;
(c) during said step of enhancing the rate of cutting of said workpiece, substantially disengaging said feed control means;
(d) during said disengaging step, controlling the rate of movement of said carriage by controlling said supporting force applied to said carriage through said force control means to produce a controlled minimum force on said blade from said carriage.

1 more element

Dependencies are inferred from the claim text.

Band saw apparatus and method

Life of this patent

Band saw apparatus and method

Life of this patent

Abstract

Claims17