US-12623295-B2 - Mandrel assembly for use with a rotary tool

US12623295B2US 12623295 B2US12623295 B2US 12623295B2US-12623295-B2

Abstract

A mandrel assembly may be used with a rotary power tool to provide a reliable and stable connection between the rotary tool and a tool accessory. The mandrel assembly provides a quick-connect/quick-release connection between the tool output shaft and the accessory via a clamping action. In particular, the mandrel assembly is movable between first and second configurations. In the first configuration, the accessory may clamped between a clamping element formed on one end of the mandrel and a collar which surrounds the mandrel. In the second configuration, the accessory may be loaded onto or detached from the mandrel assembly.

Inventors

Andres David Salazar Tello
Kevin Wasielewski

Assignees

ROBERT BOSCH GMBH

Dates

Publication Date: 20260512
Application Date: 20230512

Claims (16)

1 . A mandrel assembly, comprising: a mandrel including a mandrel first end having a mandrel clamping element, a mandrel second end that is opposite the mandrel first end, a longitudinal axis that extends through the mandrel first end and the mandrel second end, and a slot provided in an outer surface of the mandrel; a collar that surrounds the mandrel, the collar including a collar first end, a collar second end that is opposite the first end, and a sidewall that extends between the collar first end and the collar second end, the sidewall including an inner surface that defines a bore, the bore opening at the collar first end and the collar second end, the bore having a step change in diameter that defines a collar inner shoulder, and a pin that protrudes from a surface of the bore and is received in the slot; a retention washer fixed to the mandrel between the slot and the mandrel second end; and a spring that surrounds the mandrel, the spring extending between the retention washer and the collar inner shoulder, wherein when the collar is moved relative to the mandrel in a first direction, the slot is configured to permit the mandrel to move relative to the collar in both rotation through a first angle about the longitudinal axis and translation in a second direction, the second direction being opposite the first direction, and when the collar is moved relative to the mandrel in the second direction, the slot is configured to permit the mandrel to move relative to the collar in both rotation through a second angle about the longitudinal axis and translation in the first direction, the second angle being opposite the first angle.
2 . The mandrel assembly of claim 1 , wherein at a first location of the slot, the slot is configured so that a biasing force of the spring maintains the mandrel clamping element at a first distance from the collar, at a second location of the slot, the slot is configured so that a biasing force of the spring maintains the mandrel clamping element at a second distance from the collar, and the second distance is greater than the first distance.
3 . The mandrel assembly of claim 1 , wherein when the collar is moved relative to the mandrel in the first direction, the slot is configured to permit the mandrel to translate linearly in the second direction, then rotate through the first angle, and then translate linearly in the second direction.
4 . The mandrel assembly of claim 1 , wherein the first angle is 90 degrees.
5 . The mandrel assembly of claim 1 , wherein the second angle is 90 degrees.
6 . The mandrel assembly of claim 1 , wherein the first and second directions are parallel to the longitudinal axis.
7 . The mandrel assembly of claim 1 , wherein the slot is configured so that as the mandrel rotates through one of the first angle and the second angle, the mandrel also translates in a direction parallel to the longitudinal axis.
8 . The mandrel assembly of claim 1 , wherein the slot includes a first slot portion that extends linearly and in a direction parallel to the longitudinal axis, a second slot portion that adjoins the first slot portion, the second slot portion extending in a direction parallel to the longitudinal axis and circumferentially along a curved path, a third slot portion that adjoins the second slot portion, the third slot portion extending linearly and circumferentially, and fourth slot portion that adjoins the third slot portion, the fourth slot portion extending linearly and axially.
9 . The mandrel assembly of claim 8 , wherein the second and third slot portions in combination provide a path that when traveled by the pin results in a 90 degree rotation of the mandrel about the longitudinal axis.
10 . The mandrel assembly of claim 8 , wherein movement of the pin in the first slot portion corresponds to a motion of the mandrel relative to the collar in which the mandrel clamping element is translated in the first direction, movement of the pin in the second slot portion corresponds to a motion of the mandrel relative to the collar in which the mandrel clamping element is translated in the first direction and in which the mandrel rotates about the longitudinal axis, movement of the pin in the third slot portion corresponds to a motion of the mandrel relative to the collar in which the mandrel rotates about the longitudinal axis, and movement of the pin in the fourth slot portion corresponds to a motion of the mandrel relative to the collar in which the mandrel clamping element is translated in the first direction.
11 . The mandrel assembly of claim 8 , wherein the first slot portion initiates at the mandrel first end, the second slot portion, the third slot portion and the fourth slot portion are disposed between the mandrel first end and a mandrel shoulder, and the mandrel shoulder is disposed between the mandrel first end and a point of the mandrel that is midway between the mandrel first end and the mandrel second end.
12 . The mandrel assembly of claim 1 , wherein the collar includes posts that protrude from the collar first end in a direction parallel to the longitudinal axis, the collar includes lands disposed between each adjacent pair of posts, upon a relative movement in a direction parallel to the longitudinal axis between the collar and the mandrel, the slot is configured to permit the mandrel to move relative to the collar from a first configuration in which the mandrel clamping element is aligned with and abutting the lands, to a second configuration in which the mandrel clamping element is aligned with the posts and spaced apart from the posts.
13 . The mandrel assembly of claim 1 , wherein the slot includes a first mandrel location corresponding to a first locked position in which a biasing force of the spring maintains the clamping element in a retracted configuration relative to the collar, and a second mandrel location corresponding to a second locked position in which a biasing force of the spring maintains the clamping element in a retracted configuration relative to the collar.
14 . The mandrel assembly of claim 13 , wherein the first mandrel location corresponds to one end of the slot.
15 . The mandrel location of claim 13 , wherein the second mandrel location is disposed at a location between, and spaced apart from, each end of the slot.
16 . The mandrel assembly of claim 13 , wherein the first locked position corresponds to a dead end of the slot, and the second locked position corresponds to a step portion of the slot.

Description

BACKGROUND Hand held rotary tools typically include a tool housing designed to be easily held within a human hand. The housing contains an electric motor which is operable to drive a rotatable chuck of the rotary tool. A mandrel may be releasably coupled to the chuck so as to be rotatably driven by the rotary tool. In turn, an accessory may be releasably secured to the mandrel thereby enabling the rotary tool to rotatably drive the accessory. The accessory may be a cutting blade, a cut-off wheel, a polishing wheel, a grinding wheel, a sanding disc, or any other similar device. Many types of mechanisms may be used to secure the accessory to the mandrel. In one example, a mandrel includes a base having a threaded aperture and a clamping screw that engages the aperture in order to clamp the accessory between the base and the clamping screw. In this example, a tool is required to tighten the clamping screw. In another example, an accessory is connected to the mandrel via a quick connection clamp that is operated via a lever provided on the tool for that purpose. In this example, the lever mechanism adds weight, complexity and cost to the tool. In both examples, with the accessory so clamped, rotation of the mandrel by the rotary tool causes rotation of the accessory thereby allowing the user to perform work on a workpiece. Accordingly, it would be advantageous to provide a mandrel that can be used quickly and easily and does not require the use of an additional tool such as a screwdriver, or the use of a relatively small, separate component such as a clamping screw. In addition, it would be advantageous to provide a mandrel having a simple and easily operated mechanism. SUMMARY A mandrel assembly is disclosed that may be used with a rotary power tool to provide a reliable and stable connection between the rotary tool and a tool accessory. The mandrel assembly provides a quick-connect/quick-release connection between the tool output shaft and the accessory via a clamping action. The mandrel assembly includes a mandrel in the form of a rigid rod, a collar having a bore that receives the mandrel therethrough, and a spring that is disposed in the bore and surrounds the mandrel. The mandrel assembly is configured so that the spring biases the collar toward one end of the mandrel. The mandrel assembly is operable to clamp the accessory between a clamping element formed on the one end of the mandrel and the collar which surrounds a portion of the mandrel. The mandrel assembly is manually transformable between a first, retracted configuration and a second, advanced configuration. In the retracted configuration, the clamping element is engaged with the collar and the accessory may be fixed relative to the collar via a clamping force and engagement of the collar with the accessory. In the advanced configuration, the clamping element is spaced apart from the collar and the accessory can be mounted on the collar or detached from the collar. The transformation of the mandrel assembly between the first and second configurations is achieved by relative movement of the collar and the mandrel in a predetermined motion. The predetermined motion is set by the shape of slots, which may also be referred to as “guide tracks,” that are formed in the mandrel and are engaged by pins that protrude radially inward from an inner surface of the collar. A slot is provided on each of opposed sides of the mandrel. The slots are engaged by pins that protrude from an inner surface of the collar toward the mandrel. The slot follows a curvilinear path that guides the mandrel to turn 90 degrees while moving longitudinally relative to the collar. The slot is configured so that a biasing force of the spring maintains the clamping element in a given one of the retracted or advanced configurations. To that end, the slot provides two locked positions. The first locked position corresponds to the retracted configuration in which the pins are disposed in a first mandrel location, and the second locked position corresponds to the advanced configuration in which the pins are disposed in a fourth mandrel location. The first locked position corresponds to a dead end of the slot, while the second locked position corresponds to a step portion of the slot. When the pins are disposed in either of the first or second locked positions, the relative positions of the mandrel and collar are maintained without requiring the user to manually apply force. This can be compared to some conventional connection assemblies in which, in order to install an accessory, it is necessary to hold down the collar while inserting and turning the accessory itself. This combination of movements may be difficult in the conventional connection assemblies since the conventional connection assemblies may include a spring that pushes the collar against the head of the shaft. To change between the retracted and advanced configurations, the user simply moves the collar or accessory axially wi