A CONNECTION BETWEEN TWO MEMBERS SUCH AS A HUB AND FAN BLADE

Abstract: A connection between two members, such as a hub member (5) and a sheet metal fan blade member (2) such that an edge of the first member (2) is joined to a surface of the second member (5) is characterised in that the hub member (5) has a groove (15) for receiving the edge of the fan blade member (2), a shoulder (14) for supporting the fan blade member (2), the groove being adjacent the shoulder (14), and a number of segments (16b) extending from the groove (15) and directed away from the surface of the hub member (5) into engagement with the fan blade member (2) whereby the edge of the fan blade member (2) at each point of engagement has a portion extending into the groove (15). Preferably the groove (15) undercuts the shoulder (14) and the edge of the fan blade member substantially fills the cross-sectional area of the groove (15) to form a firm interlocking connection.)

Description: DESCRIPTION The present invention is directed to providing an improved interlocking connection between two members such that an edge of one member is joined to a surface of the other. The invention is particularly useful in providing a connection between a sheet member and a heavier member, such as a sheet metal fan blade and a hub. US-A-4 245 960 discloses a structure consisting of first and second members to be connected at a line of connection, wherein the first member is a thin sheet-like formation at the line of connection and has an abutting edge the second member is relatively heavier in a direction transverse to the sheet-like formation of the first member, the second member has a groove therein extending along the line of connection, such groove having a width approximately equal to the thickness of the sheet-like formation and forming two spaced upstanding shoulders, one shoulder extending beyond the other by an amount greater than the thickness of the first member , the groove having a throat extending to a base, and such one shoulder being divided into a plurality of segments comprising a group of alternate segments and a group of intermediate segments the first member is formed to be seated on the upper edge of the other shoulder with the abutting edge in contact with the segments of the one shoulder , each o f the intermediate segments having free ends for extending beyond the abutting edge and for being directed toward and into engagement with the first member which, at each point for engagement with the intermediate segments, has a portion for extending into the groove to prevent relative movement of the first and second members. The present invention seeks to provide an improved connection between such members. According to one aspect of the present invention the groove of the structure is wider at its base than at it's throat so as to form an undercut, the undercut having an outer edge defined by the outer end of the throat, said outer edge being pressed into the edge of the first member when the intermediate segment is directed toward and into engagement with the first member. Preferably, the connection is between a sheet metal member having an aperture and a hub member with the one shoulder being an axially extending sleeve of the hub and the abutting surface of the sheet metal member being an edge of an aperture receiving the sleeve. If desired, the deformed intermediate segments can be deformed further by applying pressure at points on a portion of the segment so as to further extrude the edge of the abutting surface into the enlarged or wide base portion of the groove. Preferably, the enlarged portion of an annular groove extends radially inwardly and the groove can have various cross-sectional shapes. According to another aspect of the present invention there is provided an assembly having a groove which is wider at its base than at its throat so as to form an undercut, the undercut having an outer edge defined by the outer end of the throat, said outer edge being pressed into the edge of the first member when during assembly of the members said segments are directed toward and into engagement with the first member. Preferably, the portions of the wall of the second member between the segments are directed away from the surface of the second member so as to firmly engage the edge of the first member. An embodiment of the invention will now be described in detail by way of example only and with reference to the accompanying drawing, in which: Fig. 1 is a side elevational view of a fan blade structure mounted on a motor-driven shaft; Fig. 2 is an enlarged axial cross-sectional view of a hub member and a portion of the cooperable blade member prior to assembly; Fig. 3 is a top plan view of a completed assembly in accordance with the present invention; Fig. 4 is a partial cross-sectional view taken on lines IV-IV fo Fig. 3; Fig. 5 is a partial cross-sectional view similar to Fig. 4 illustrating the connection with further pressing; Fig. 6 is a cross-sectional view taken on lines VI-VI of Fig. 3; Fig. 7 is a partial cross-sectional view similar to Fig. 5 without the blade member showing a modification in the cross-section of the groove; and Fig. 8 is a cross-sectional view similar to Fig. 7 showing a further modification of the groove. The principles of the present invention are particularly useful for forming an interlocking connection in a fan blade structure generally indicated at 1 between a first member in the form of a blade member 2 having a central portion 3 having a generally laminar configuration from which extends a plurality of blades 4. The central portion 3 is connected to a second member in the form of a hub member 5 which enables the blade structure 1 to be mounted on a drive shaft 6 of a motor 7. A large number of blades of this type are constructed from sheet metal suitably configured and bent to form the blade member 2 which is secured in a separately formed hub 5. Referring more to Figs. 2 to 6, the hub member 5 is provided with a cylindrical tubular body portion 8 having a central bore 9 adapted to receive a driven shaft of a motor or other driving means with the body portion 8 having a relatively thick wall with a threaded bore 10 which receives a set screw 11. The set screw 11 enables locking the hub onto the shaft which is inserted into the bore 9. Integrally formed with the body portion 8 and extending in an axial direction from one end of the latter is a coaxial sleeve 12 which is relatively thin in a radial thickness as compared with the corresponding thickness of the body portion 8. The outer diameter of the sleeve 12 is approximately equal to the diameter of a bore 13 in a central portion 3 of the blade member 2 so that the sleeve 12 may be readily inserted into the bore 13 and fit snugly therein. The body portion 8 is also provided with an annular shoulder 14 disposed adjacent the inner end of the sleeve 12 and spaced therefrom by an annular groove 15 having a radial thickness which is approximately equal to the thickness of the central portion 3 of the blade member. As disclosed in US-A-4,245,960, the sleeve 12 of the hub member is inserted into the bore 13 with the bottom surface 28 of the central portion 3 as illustrated in Fig. 2 resting or seated on the shoulder 14. Then with a suitable tool, a plurality of shear cuts are formed in the free end of the sleeve 12 to divide the same into a plurality of axially extending segments 16a and 16b (Fig. 4). The alternate segments 16a are deformed slightly to provide a flared configuration as illustrated in Fig. 6 whereby the outer surface of each segment 16a is brought into firm engagement with a peripheral edge of the bore 13 but insufficient to materially deform the peripheral portion of the blade member. The intermediate segments 16b, however, are bent to a considerably greater extent than the alternate segments 16a so that the intermediate segments are bent over to engage the adjacent upper face of the central portion of the blade member as viewed in Fig. 4. As previously mentioned, the blade member 2 is formed from a relatively soft material while the hub member 5 is formed from a relatively harder material so that upon bending over the segment 16b, a portion of the member 3 is sheared from the latter along the side edges of the segment and flows into the groove 15 as indicated by portions 17 in Fig. 4. The amount of flow depends on the pressure applied to an upper surface of each segment 16b. As illustrated in Figs. 5 and 6, the groove 15 has an enlarged width at its base 18 which is wider than the throat or mouth 19 adjacent the shoulder 14. In the illustrated embodiment of Fig. 6, it is noted that the increased width forms an undercut 20 of a portion of the sleeve having the segments 16a and 16b. While the deforming of the segments 16b causes a portion 17 to flow into the groove 15, applying additional pressure on surfaces 21 or 22 (Fig. 5) extrudes or causes more material to flow into the groove 15. This greater flow is illustrated at 23 in Fig. 5 and causes a filling of the groove adjacent each segment 16b which has been subjected to this additional pressure. The additional pressure can be created by either a second pressing of the assembly of Fig. 4 or by providing pressure surfaces or projections on the tool which is used to deform the segments 16b into the deformed condition. As illustrated in Fig. 6, the segment 16a, which is not deformed to any great extent, does not cause the edge portion to be deformed into the groove 15. Thus, the deforming of the segment 16b relative to the segment 16a causes a splined connection between the blade member 2 and hub member 5 which is very durable, particularly due to the increased width of the groove 15 adjacent the bottom 18. Thus, the material flowing into the groove forms an interlocking enlargement to improve the interlocking connection between the sheet metal member and hub. To form the groove 15, as best illustrated in Figs. 2 and 6, the hub can have the groove undercut by means of a tool. As illustrated, the groove has an undercut 20 which gives it a cross-section of a five-sided configuration. Instead of an undercut configuration of Figs. 2 and 6, a hub 5′ can have a groove 15′ which has an L-shaped configuration. Another modification is illustrated by the hub 5" of Fig. 8 which has a groove 15" which has a circular base or round configuration 18" with a throat 19". In each instance, the groove has an undercut portion to form an enlarged base to provide interlocking of the member to the hub. While the invention has been described with regard to connecting a sheet metal member to a hub, it also can be used to connect an edge of a sheet member in a groove of a larger member whether the groove is an annular groove or a straight linear groove. In each instance, the deforming of the segments of a shoulder or sleeve cause alternate portions of the abutting edge of the sheet member to flow into the groove having the enlarged or wider base to provide an interlock connection or a spline connection which will transfer motion along the groove and prevent disengagement. If the groove is annular, the connection is good for transferring torque.

Claims: A structure consisting of first and second members (2, 5)to be connected at a line of connection, wherein the first member (2) is a thin sheet-like formation (3) at the line of connection and has an abutting edge, the second member (5) is relatively heavier in a direction transverse to the sheet-like formation (3) of the first member (2), the second member has a groove (15) therein extending along the line of connection, such groove (15) having a width approximately equal to the thickness of the sheet-like formation (3) and forming two spaced upstanding shoulders (14, 12), one shoulder extending beyond the other by an amount greater than the thickness of the first member (2), the groove (15) having a throat (19) extending to a base (18), and such one shoulder being divided into a plurality of segments (16a, 16b) comprising a group of alternate segments (16a) and a group of intermediate segments (16b) the first member (2) is formed to be seated on the upper edge of the other shoulder (14) with the abutting edge in contact with the segments (16a, 16b) of the one shoulder (12), each of the intermediate segments (16b) having free ends for extending beyond the abutting edge and for being directed toward and into engagement with the first member (2), which at each point for engagement with the intermediate segments (16b), has a portion for extending into the groove (15) to prevent relative movement of the first and second members, characterised in that the width of the groove (15) at the base (18) is greater than the width adjacent to the throat (19) to form an undercut (20) of the one shoulder (12), the under cut (20) having an outer edge defined by the outer end of the throat (19), said outer edge being pressed into the edge of the first member (2) when the intermediate segment (16b) is directed toward and into engagement with the first member (2). A structure according to claim 1, wherein the alternate segments (16a) extend outwardly beyond the abutting edge and are flared laterally toward the abutting edge. A structure according to claim 1 or 2, wherein the groove (15) has a depth approximately equal to the thickness of the sheet-like formation (3) and the undercut (20) extends beneath a portion of the one shoulder (12). A structure according to claim 1, 2 or 3, wherein the second member (5) and the groove (15) are annular, the one shoulder (12) being a sleeve-shaped member extending axially from the hub (8) and the base (18) of the groove extends radially inwardly to undercut a portion of the one shoulder (12). A structure according to claim 4, wherein the intermediate segments (16B) have been further deformed to cause the edge of the member (2) adjacent each intermediate segment (16b) to flow into the groove (15) so as substantially to fill the base (18) thereof. An assembly comprising first and second members (2, 5) connected together such that an edge of the first member (2) is joined to a surface of the second member (5), wherein the first member (2)is a sheet metal member having a circular aperture (13) whose edge is connected to the second member (5) and which has a laminar configuration (3) in the region of the edge; the second member (5) is a hollow cylindrical member having one open end and has (a) a groove (15) which receives the edge of the first member (2), which edge of the first member (2) at each point of engagement with a number of segments (16b) formed on the second member substantially fills the cross-sectional area of the groove (15), (b) a pair of shoulders (12, 14), with one shoulder (12) extending beyond the other shoulder (14) which supports the first member (2), the groove (15) being adjacent the other shoulder (14); and (c) said number of segments (16b) comprising alternate portions of the wall of the second member (5) extending from the other shoulder (14) to the open end and extending from the groove (15) and directed away from the surface of the second member (5) into engagement with the surface of the first member (2), whereby the edge of the first member (2) at each point of engagement with the segments (16b) has a portion extending into the groove (15), characterised in that the groove has a throat (19) extending to a base (18) which is wider than the throat (19) to form an under cut (20) of the one shoulder (12), the under cut (20) having an outer edge defined by the outer end of the throat (19), said outer edge being pressed into the edge of the first member (2) when during assembly of the members said segments (16b) are directed toward and into engagement with the first member (2). An assembly as claimed in claim 6, wherein the portions (16a) of the wall of the second member (5) between the segments (16b) are directed away from the surface of the second member (5) so as to firmly engage the edge of the first member (2). An assembly or structure as claimed in any preceding claim, wherein the groove (15) has a substantially square cross-section. An assembly or structure as claimed in any of claims 1 to 7, wherein the groove (15') has a substantially L shaped cross-section. An assembly or structure as claimed in any of claims 1 to 7, wherein the groove (15") has a rounded base (18").

Inventors: MATTHEWS, DAVID G
Applicants: MATTHEWS, DAVID G
Application year: 1986
Main classification: F04D29
IPC codes: F16D1, F04D29, B21D39