EP0635333A1

EP0635333A1 - Oscillating spindle sander

Info

Publication number: EP0635333A1
Application number: EP94630029A
Authority: EP
Inventors: David Earl Beth; James Irvin Metzger, Jr.
Original assignee: Emerson Electric Co
Current assignee: Emerson Electric Co
Priority date: 1993-07-19
Filing date: 1994-05-05
Publication date: 1995-01-25
Also published as: JPH0732260A; CA2114818A1

Abstract

The oscillating spindle sander (1) includes a housing or frame (3) which supports a worktable (5). A drum (9) having a sanding surface extends above the worktable (5) to sand a workpiece. The drum (9) is driven by a motor (15) which directly drives the drum (9) both rotationally and translationally.

Description

Background of the Invention

This invention relates to spindle or drum sanders and in particular to an oscillating spindle sander.
Spindle sanders include a rotating drum having a sanding surface to sand the edges of workpieces. To improve the sanding ability of drum sanders, sanders have been designed which both oscillate and rotate the sanding drum. However, motors typically output only rotational motion. They do not directly output translational motion which is needed to oscillate the sanding drum. Thus, to induce oscillation, a series of pulleys, cylinders, or cams have been used. The extra moving parts required by such a construction not only add to the cost and complexity of the sander, but increases the likelihood of a malfunction. One such oscillating drum sander is shown in U.S. Patent 4,821,457 to Ianuzzi which uses a hydraulic cylinder having a pair of control switches to create vertical oscillation of the spindle.

Summary of the Invention

One object of this invention is to provide an oscillating spindle sander in which a single motor directly drives the spindle both rotationally and translationally.
Another object is to provide such a sander which is made of a minimum number of parts, is easy to construct and maintain, and is economical to produce.
These and other objects will become apparent to those skilled in the art and in light of the following disclosure and accompanying drawings.
Briefly stated, the invention provides an oscillating spindle sander in which the sander is directly driven both rotationally and translationally. The sander includes a housing, a worktable for supporting a workpiece, a drum extending through the worktable and having a sanding surface, and a direct drive motor for directly transmitting rotational and reciprocal motion to the drum. The motor includes a stator, a rotor, a first means for producing a first magnetic field for inducing rotational motion and a second means for producing a second magnetic field for inducing translational motion. By controlling the creation of the first and second magnetic fields, the motor will directly drive the drum both rotationally and translationally.

Brief Description of the Drawings

FIG. 1 is a perspective view of an oscillating spindle sander of the present invention;
FIG. 2 is a side elevational view of the sander with a motor shown in phantom;
FIG. 3 is a schematic of the electrical connection of the motor; and
FIG. 4 is a cross-sectional view of a motor used to rotate and translate the spindle sander.

Description of the Preferred Embodiment

An oscillating spindle sander 1 includes a frame or stand 3 having a flat worktable 5. Worktable 5 has a hole 7 formed in the center thereof to accommodate a sander drum 9 having an outer sanding surface. As will be explained below, drum 9 rotates and oscillates to sand the edges of a workpiece 11, shown in phantom in FIG. 1.
Drum 9 is mounted on a shaft 13 of a motor 15 to extend through hole 7. Drum 9 is sized so that a sanding surface is always level with the top of the worktable when the sander is operated (e.g., there is no gap formed between the bottom of the drum and the top of the worktable). Motor 15 directly drives shaft 13 both rotationally and translationally to directly induce both the oscillatory and rotational motion of drum 9. By directly driving the oscillatory motion of the drum, the complex systems presently used to create the drum's translational motion are not needed, simplifying the construction and operation of sander 1.
Motor 15, which is shown in FIG. 4, is preferably the type of motor described in U.S. Patent 5,045,741, which is incorporated herein by reference. Motor 15 has a shell 17 closed by a pair of endshields 19. Bearings 21 in endshields 19 rotationally support shaft 13. Motor 15 includes a stator 23 having windings 25, which create a magnetic field, and a rotor 27 having an armature 29. Armature 29 is connected to a commutator 31 by two sets of brushes or contacts which create two separate magnetic fields in the rotor. One of the rotor's magnetic fields is substantially perpendicular to the stator's magnetic field to rotate shaft 13 and the other is substantially parallel to the stator's magnetic field to provide axial movement of the shaft 13. The commutator is operable to be connected to one or both of the sets of brushes to selectively rotate and/or oscillate the shaft 13 and hence the drum 9.
Turning to FIG. 3, motor 15 is connected to a source of current by a circuit 33. Circuit 33 has a pair of parallel wires 35 and 37 which are operably connected to the motor 15 to provide current thereto. A rectifier 39 is placed in line 35 to convert AC current to DC current to rotate rotor 27, and an electronic control 41 is disposed in line 37 to control varying DC current or the cycle of AC current to control the translation of the shaft 13. A switch 43 connects and disconnects the motor 15 to and from the source of current to turn the motor 15 on and off.
As can be seen, the foregoing provides a reciprocating and oscillating drum sander in which the drum is reciprocated and rotated directly by a single motor. This eliminates the need for second motors or complex cylinder, pulley, or cam systems which would otherwise be used to reciprocate the sander. The foregoing disclosure is set forth for illustrative purposes only. Variations within the scope of the appended claims may be apparent to those skilled in the art.

Claims

An oscillating spindle sander having a housing, a worktable for supporting a workpiece, a drum extending through said worktable and having a sanding surface, and a direct drive for directly transmitting rotational and reciprocal motion to said drum.
The oscillating spindle sander of claim 1 wherein said drive is a motor, said motor having a rotor shaft to which said drum is fixed, and said motor being operable to impart both rotational and reciprocal motion to said shaft.
The oscillating spindle sander of claim 2 wherein said motor includes a stator, a rotor, a first means for producing a first magnetic field for inducing rotational motion and a second means for producing a second magnetic field for inducing translational motion.
The oscillating spindle sander of claim 3 wherein a said first and second means are connected to a source of current, a rectifier being disposed between said source of current and said first means to deliver DC current to said first means.
The oscillating spindle sander of claim 3 wherein said first and second means are connected to a source of current, a controller being disposed between said source at said second means to control said translational motion of said drum.