WO2011056560A1

WO2011056560A1 - Mechanism for connecting a chuck to a power tool

Info

Publication number: WO2011056560A1
Application number: PCT/US2010/054076
Authority: WO
Inventors: Joao Norona
Original assignee: Black & Decker Inc.
Priority date: 2009-10-26
Filing date: 2010-10-26
Publication date: 2011-05-12

Abstract

A mechanism (300) for connecting a chuck (390) to a spindle (320) is disclosed. The mechanism (300) includes an element (450) that secures the chuck (390) to the spindle (320), an element (450) that allows torque to be transferred from the spindle(320) to the chuck(390), and an element (382, 386) that ensures that the rotational axis of the chuck is aligned with the rotational axis (50) of the spindle (320). The connection mechanism (300) also includes a feature (350) that enables the connection end (312) of the tool accessory (310) to be inserted into the chuck (390) past portion of the connection mechanism (300). The portion of the tool accessory (310) that extends past the connection mechanism (300) represents a net shortening of the total length (figure 1) of the tool which is defined as the total length from the back of a tool (1) to the tip of the tightened tool accessory (310).

Description

MECHANISM FOR CONNECTING A CHUCK TO A POWER TOOL

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Utility Application No. 12/911,998 filed October 26, 2010, U.S. Provisional Application No. 61/254,813, filed October 26, 2009 and U.S. Provisional Application No. 61/297,481, filed January 22, 2010, titled "Mechanism for Connecting A Chuck To A Power Tool".

FIELD OF THE INVENTION

[0002] The present invention relates to a device for securing a tool accessory (e.g., a drill bit) in a chuck. More particularly, the present invention discloses a mechanism for securing a chuck to the spindle of a power tool.

BACKGROUND

[0003] As illustrated in Figure 1, many power tools 1 include a motor 3 having a rotating shaft 4. The rotating shaft 4 is connected to a gear mechanism 5 which in turn is connected to a rotatable spindle 6. The spindle 6 has an axis of rotation 50. When the motor 3 is energized, it transfers rotational energy to the spindle 6 via the gear mechanism 5. The spindle 6 is thereby rotatable by the power of the motor 3. A chuck 7 is rotatably secured to the spindle 6 about rotation axis 50 of spindle 6. A tool accessory 8 is connectable to the spindle 6 via the chuck 7. The chuck 7 is adjustable to secure various size tool accessories 8 to the spindle 6.

[0004] The chuck 7 includes an opening for accommodating the tool accessory 8. After inserting the tool accessory 8 into the opening, jaws (not shown) of the chuck converge and grip the tool accessory 8 in a manner well known in the art. After the tool accessory 8 is secured in the chuck 7, the drill can be energized to rotate the chuck 7 together with the tool accessory 8 to perform a (e.g., drilling) function.

[0005] One important design parameter of power tools (e.g., drills) is the dimension measured from the rear of tool to the end of the tool accessory (Total Length). The Total Length includes the spindle/chuck connection. Accordingly, reducing the length of the mechanism that connects the chuck 7 to the spindle 6 results in a reduction in Total Length. Therefore, the Total Length is related to the method of connection between the chuck 7 and the spindle 6. [0006] Any effective design for connecting the chuck 7 to the spindle 6 must include a mechanism for transferring torque from the spindle 6 to the chuck 7, a mechanism for preventing removal of the chuck 7 from the spindle 6, and a mechanism for ensuring alignment of the rotational axes 50 of the chuck 7 and spindle 6. When the axes are misaligned runnot occurs. Runnout is chuck vibration/wobble that occurs when, after connection, the rotational axis of the chuck 7 is not collinear with the rotational axis 50 of the spindle 6. [0007] The structure of a particular connection mechanism also affects how the tool accessory 8 is able to be situated in the chuck 7. It would be beneficial to develop a connection mechanism that fulfills the three above-requirements while allowing the tool accessory 8 to be inserted as far as possible into the chuck 7 to minimize the tool's Total Length.

SUMMARY

[0008] Generally, the present specification discloses a connection mechanism for securing a chuck to a spindle of a power tool. In one embodiment of the present invention, the spindle includes a spindle bore disposed perpendicular to the rotational axis of the spindle. In addition, the chuck includes a through bore that is perpendicular to the rotational axis of the chuck. The chuck is connected to the spindle by inserting the spindle into a chuck bore along the axis of rotation of the chuck and spindle. The chuck is then rotated on the spindle so that the chuck bore of the chuck is aligned with the spindle bore of the spindle. A connection pin is then inserted through both the chuck bore and the spindle bore to lock the chuck rotationally with respect to the spindle.

Torque is then able to be transferred from the spindle through the connection pin to the chuck and tool accessory based on the shear strength of the connection pin. The connection pin also prevents the chuck from being removed from the spindle. Finally, the end of the spindle includes an axially situated shaped bore sized to receive the insertion end of a tool accessory. The axial length of the portion of the accessory that is inserted into the shaped bore represents a net shortening of the Total Length of the tool compared to a connection mechanism that does not provide such an opening in the spindle. [0009] The foregoing merely discloses one possible embodiment of the present invention. Numerous other methods of connection may be utilized as long as the chuck is secured to the spindle, as long as torque can be transferred from the spindle to the chuck, as long as the connection mechanism secures the chuck to the spindle in a manner that ensures that the rotational axes of the chuck and spindle are collinear, and as long as the connection mechanism accommodates the insertion end of a tool accessory.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 illustrates an example of one type of power tool capable of utilizing the chuck/spindle connection mechanism of the present invention.

[0011] Figure 2 illustrates a cross-sectional view of a conventional mechanism for securing a chuck to a spindle.

[0012] Figure 3 illustrates a cross-sectional exploded view of the mechanism of Figure 2.

[0013] Figure 4A illustrates a cross-sectional view of an embodiment of an improved chuck attachment mechanism showing the chuck connected to the spindle by a connection pin.

[0014] Figure 4B illustrates front view of the embodiment of Figure 4A.

[0015] Figure 5 illustrates a cross-sectional exploded view of the mechanism of Figure 4.

[0016] Figure 6 illustrates a cross-sectional view of another embodiment of the present invention.

[0017] Figure 7 illustrates a cross-sectional view of an embodiment of the present invention.

[0018] Figure 8 illustrates a cross-sectional exploded view of the embodiment of Figure 7.

[0019] Like reference numerals have been used to identify like elements throughout this disclosure.

DETAILED DESCRIPTION

[0020] A mechanism for connecting a chuck to a spindle of a power tool is disclosed in the present specification. Figures 2 and 3 illustrate a conventional connection mechanism 100 for connecting a chuck to a spindle. Figure 3 shows an exploded cross-sectional view of connection mechanism 100.

[0021] Connection mechanism 100 includes a spindle 120, a chuck 190, and a connection member 260. Spindle 120 that extends from an opening (not shown) in an outer housing of the power tool. Spindle 120 includes a tool end 130 that extends into the power tool and a chuck end 140 to which a chuck is connectable. Chuck end 140 includes an outer surface having male threads 150 thereon. Chuck end 140 also includes a bore 160 defining an inner surface on which female threads 170 are located. Spindle 120 also includes a stop 180 against which chuck 190 rests when fully connected to spindle 120.

[0022] Chuck 190 includes a chuck body 194 having a spindle end 200 and an accessory end 210. Tool end 200 includes a connection member in the form of a chuck bore 220. Chuck bore 220 has a connection part formed as female threads 230 disposed on an inner surface of chuck bore 220. Accessory end 210 of chuck 190 includes an opening 240 for receiving a connection end 112 of an accessory 110. A through passage 250 connects chuck bore 220 and opening 240. [0023] Connection mechanism 100 also includes a connection member 260 in the form of a threaded fastener. Connection member 260 includes an outer surface having male threads 270 disposed thereon and a head 280.

[0024] Connection member 100 is assembled by thredably connecting spindle 120, chuck 190, and connection member 260. The bore of spindle end 200 of chuck 190 is sized to receive chuck end 140 of spindle 120. Accordingly, female threads 230 of chuck 190 receive male threads 150 of spindle 120. Through passage 250 is slightly larger than male threads 270 to allow connection member 260 to be inserted into opening 240 and through threaded passage 250. Female threads 170 of spindle 120 are sized to threadably receive male threads 270. Head 280 is larger than through opening 250 to prevent head 280 from passing therethrough. Figure 2 shows the assembled connection mechanism 100. The threaded connection between threads 230 of chuck 190 and threads threads 170 of spindle 120 and threads 270 of connection member 260. This reverse threading prevents the chuck 190 from being inadvertently removed from spindle 120 during operation of the tool.

[0025] A chuck/spindle connection design must take runout into account. In the design shown in Figs. 2 and 3, the threaded connection between chuck 190 and spindle 120 is not relied on as a precision connection. Therefore, the threads are not necessarily relied on to align the rotational axis of chuck 190 with the rotational axis 50 of spindle 120. The final alignment of the chuck 190 and spindle 120 with rotational axes 50 occurs when rear surface 186 of chuck 190 tightly contacts stop surface 184 of spindle 120.

[0026] Figures 4A, 4B, and 5 illustrate an improved connection mechanism 300 showing an improved connection system. Connection mechanism 300 includes a number of features that correspond to connection mechanism 100. Accordingly, corresponding reference numbers in connection mechanism 300 are the same as in connection mechanism 100 plus 200. [0027] Spindle 320 includes a spindle bore 420 that passes through a central part of spindle 320 perpendicular to rotational axis 50. Spindle bore 420, however, need not pass through the center part of spindle 320 as long as it passes through spindle 320.

Spindle 320 also includes a shaped bore 350 at a chuck end 340 thereof. Shaped bore 350 has a shaped (e.g., hexagonal) cross section. Spindle 320 also includes a stop 380 against which chuck 390 can rest when connected to spindle 320. However, in this design, chuck 390, is not required to rest on stop 380 and these parts may not touch at all.

[0028] Chuck 390 includes a chuck through bore 430 that defines a through bore in the chuck 390 that is perpendicular to and intersects rotational axis 50 of chuck 390 when chuck 390 is assembled to the tool. [0029] To assemble connection mechanism 300, a chuck bore 400 receives chuck end 340 of spindle 320. Chuck through bore 430 need not pass through the center of chuck 390 as long as chuck through bore 430 intersects with chuck bore 400. Chuck 390 is then rotated until spindle bore 420 is aligned with chuck through bore 430. A connection pin 450 is then inserted into chuck through bore 430 and through spindle bore 420. Connection pin 450 therefore prevents chuck 390 from rotating relative to spindle 320. Connection pin 450 is therefore also the means by which spindle 320 transfers torque to chuck 390 through the shear strength of the connection pin 450. Opening 440 communicates with chuck bore 400 so that chuck end 340 of spindle 390 is exposed in opening 440 when connection mechanism 300 is assembled. Spindle bore 350 can therefore receive a connection end 312 of an accessory 310. As discussed above, when spindle bore 350 includes a hexagonal cross-section, a hexagonal accessory connection end 312 is rotationally lockable in spindle bore 350. [0030] Figures 2, and 4A illustrate dimensional measurements with which the Total Length can be further defined. Dimension D 1 represents the length of a tool accessory 8 that can be received in a chuck 190 in connection mechanism 100.

Dimension D2 represents the length of a tool accessory 8 that would be received in a chuck 390 of connection 300 if it were not for shaped bore 350 provided in the design of connection mechanism 300. Dimension D3 represents the length of a tool accessory 8 that can be received in a chuck 390 as a result of the design of connection mechanism 300. The difference between length Dl and D3 represents the reduction in Total Length achieved by utilizing connection mechanism 300 rather than connection mechanism 100. Similar comparisons may be made with other embodiments disclosed below.

[0031] The present invention is not is not limited to the embodiment disclosed above. For example, the threaded connection design of Figures 2 and 3 can be utilized without connection member 260 to define another embodiment of a connection mechanism 500. Figures 7 and 8 illustrate connection mechanism 500. As discussed above in the embodiment of Figure 2, connection member 260 is necessary in the design described above to prevent the male threads 150 of spindle 120 from loosening from female threads 230 of chuck 190. In connection mechanism 500, to prevent loosening of chuck 190 from spindle 120 without utilizing connection member 260, chuck 190 is tightened to spindle 120 by tightening threads 170, 230 until loosening would require a torque greater than the total torque the tool is capable of applying. The tool would then be incapable of generating a reverse torque that could loosen chuck 190 from the tool. This over torque connection mechanism would ensure that chuck 190 cannot be unexpectedly removed from the spindle and would also enable torque to be transferred from the spindle to the chuck. The amount of torque that able to be transferred from spindle 120 to chuck 190 is limited only by the maximum torque of the tool. The remainder of the design is the same as the design disclosed in Figures 2 and 3.

Therefore, alignment of chuck 190 with spindle 120 is ensured when rear surface 186 of chuck 190 tightly contacts stop surface 184 of spindle 120. In connection mechanism 500, because connection member 260 is absent, an opening such as the shaped bore 350 of the design of Figures 4A and 5 can be included in spindle 120. [0032] Figure 6 shows an embodiment of construction mechanism 700 which is based on connection mechanism 100 above. Connection mechanism 700 operates in the same manner as connection member 100 except that the various members are dimensioned differently. Accordingly, reference numbers are duplicated from connection member 100. In this design, the diameter of connection member 260 is enlarged enough so that an opening such as the shaped bore 350 of construction mechanism 100 can be included in the end of connection member 260 near head 280. In addition, the diameter of spindle 120 would also be appropriately increased to accommodate the larger diameter of the connection member 260. [0033] Other various embodiments are contemplated within the bounds of the invention disclosed herein. As mentioned above, designs need only connect the chuck to the spindle in a manner that prevents the chuck from being removed from the spindle, that allows torque to be transferred from the spindle to the chuck, that secures the chuck to the spindle in a manner that aligns the rotational axis of the chuck and the rotational axis of the spindle, and that accommodates the insertion end of the tool accessory into and/or past the connection mechanism.

Claims

1. A connection mechanism for connecting a tool holder to a power tool comprising:

a power tool body, a chuck body, a spindle projecting forward of the power tool body and rotatable on the power tool body, a motor, a power transfer mechanism for transferring power of the motor to rotate the spindle;

a first through passage in the spindle, a second through passage in the chuck body, a connector positioned in the first and second passages to prevent relative rotation between the spindle and the chuck body.

2. The connection mechanism of claim 1, wherein a forward portion of the spindle extends forward of the connector, and wherein the forward portion includes a receptacle for accommodating a tool accessory.

3. The connection mechanism of claim 1, wherein the receptacle is a hex socket.

4. A power tool including a connection mechanism for connecting a tool holder to the power tool comprising:

a male thread on the spindle for threadable connection to a female thread on the chuck body; the spindle includes a stop surface and the chuck body includes a rear surface;

wherein the rear surface of the chuck body is tightened against the stop surface of the spindle until the force necessary to release the friction between the stop and rear surfaces is greater than the operating torque of the power tool.

5. The power tool of claim 4, wherein the spindle also includes a female thread for receiving a male thread of a connection member, the connection member passes through a chuck body opening and through a narrowed through passage to secure the chuck body to the spindle.

6. The power tool of claim 5, wherein the spindle also includes a shaped receptacle for receiving a correspondingly shaped end of a tool accessory.