Patent Application
20210228946
Not Applicable
Not Applicable
Not Applicable
This application relates to a skewed shim shaft adapter and an elemental shaft adapter which, are interchangeable in spite of the fact that they are shaft adapters belonging to two different types. This interchangeability provides for a first golf club head assembly comprising the skewed shim shaft adapter secured to a head, or a second golf club head assembly comprising the elemental shaft adapter secured to the head. This interchangeability is particularly beneficial in retrofitting the elemental shaft adapter to a head manufactured to be fitted with the skewed shim shaft adapter.
A golf club includes a shaft, a head, and a shaft connection which provides for shaft attachment to the head. The head has a face for striking a golf ball, a back which is opposite the face, a bottom surface called a sole, a top surface called a crown, a heel which is its side closest to the golfer, a toe which is its side farthest from the golfer, and, located near the heel, a tubular extension called a neck. In what is herein called a “simple” golf club, the shaft connection is a direct shaft connection in which the shaft is directly attached to the head by securing it in a cavity, commonly called a hosel, located in the head's neck. The hosel typically has a hosel axis about which it is substantially symmetric, the shaft typically has a shaft axis about which it is substantially symmetric, and in the simple golf club with its direct shaft connection, the shaft axis and the hosel axis are typically substantially co-linear.
A golf club has various angular properties, or relationships, of its head with respect to its shaft axis, among them being the golf club's loft angle, lie angle, and face angle. These angles are normally defined as being the angles the head makes with the shaft axis when the golf club is in a centered, squared, position, or CSP. To attain the CSP, several conditions together must be met. With the shaft axis lying in a shaft plane which is perpendicular to a ground plane, the centered condition is met if the head's sole touches the ground plane at a point which is centered on the head's face. The squared condition is met if the head's face line, a line defined by two points on the face equally distant horizontally from the face's center and halfway up the face from the ground plane, is parallel to the shaft plane. With the club in its CSP, loft angle is the angle the head's face makes with the shaft plane, lie angle is the angle the shaft axis makes with the ground plane, and face angle is the angle the face line makes with the shaft plane, which is zero if the club is in its CSP.
The direct shaft connection described above does not provide for adjustment of the club's angular properties because the shaft axis is always substantially co-linear with the hosel axis. In order to provide for adjustment in some golf club angular properties and to provide for easy shaft interchange, a second type of connection, shaft adapter connection, is used. In shaft adapter connection, the shaft is secured to a shaft adapter and the shaft adapter is secured to the head using a fastener, thereby providing for relatively simple shaft interchange. Two types of shaft adapter in use today are herein defined as being an “elemental” type and a “skewed shim” type.
In these discussions, the following terms are defined as follows. For golf clubs in which a direct shaft connection is employed, the word “hosel” is easily defined; it is a cavity in the neck into which the shaft is secured. When a shaft adapter is employed for shaft attachment, definition of the word “hosel” is not obvious. In this case, a cavity in the head into which the shaft adapter is secured is herein defined as being a hosel, and a cavity located in the shaft adapter into which the shaft is secured is herein defined as being a “shaft adapter socket”, or simply a “socket”. The socket has an axis and it is herein assumed that it is substantially co-linear with the shaft axis. Also, the words proximal and distal describe spatial relationships with respect to the head.
Additionally, a term “indexing structure” is used herein, and this term indicates a structure, typically having a toothed profile, which is “embodied” in a component. Two indexing structures, a first and a second, are described herein as being “engageable”, indicating that they are capable of “engaging” which thereby restrains them from relative rotation, that is, rotation of the first indexing structure with respect to the second indexing structure. Since the first indexing structure is embodied in a first component, and the second indexing structure is embodied in a second component, saying that the indexing structures are engaged, and therefore restrained from relative rotation, means that the components are also restrained from relative rotation, that is, rotation of the first component with respect to the second component. Typically, in shaft adapter connection, an indexing structure is embodied in the head, either in its hosel or its neck, and this head indexing structure is engageable with an indexing structure embodied in a component of the shaft adapter. Engagement of these indexing structures results in the component of the shaft adapter being restrained from rotation with respect to the hosel, the hosel axis, and the neck.
The elemental type of shaft adapter is the simpler of these two shaft adapter types. In typical form, a shaft adapter of the elemental type comprises two components, an elemental shaft adapter fitting and an elemental shaft adapter fastener. A socket is located in a distal end of the elemental shaft adapter fitting and a threaded hole is located in its proximal end. The head's hosel is accepting of a proximal portion of the adapter fitting, and the fastener passes through a hole in the proximal end of the hosel and engages the fitting's threaded hole to secure the fitting in the hosel. The head embodies an indexing structure, typically embodied in its hosel, and the elemental shaft adapter's indexing structure is embodied its fitting. These indexing structures are engageable, typically in any one of a plurality of rotational positions of the shaft adapter's indexing structure with respect to the head's indexing structure. In what is herein defined as being a “straight axis” elemental shaft adapter, the socket axis is substantially co-linear with the hosel axis in all rotational positions of the shaft adapter's indexing structure with respect to the head's indexing structure. In what is herein defined as being a “skewed axis” elemental shaft adapter, the socket axis is skewed, not parallel, with the hosel axis. The straight axis elemental shaft adapter, due to the co-linear relationship of the socket axis with the hosel axis, does not provide for adjustment of a golf club's angular properties. The skewed axis elemental shaft adapter, due to the skewed relationship between the socket axis and the hosel axis, does provide for adjustment of a club's angular properties.
An example of a skewed axis elemental shaft adapter is presented in U.S. Pat. No. 8,303,431 by Beach et al, particularly referencing FIGS. 2-4 and pages 9 and 10 of the specification. In Beach, the head's indexing structure is a “hosel insert 200” which is located at a proximal end of a “hosel opening 340”. The shaft adapter's indexing structure is located on a lower portion of a “shaft sleeve 100” and is “a lower portion 150 having a non-circular configuration complementary to a non-circular configuration of the hosel insert 200”.
The skewed shim type of shaft adapter is a bit more complicated. In typical form, a shaft adapter of the skewed shim type comprises several components, including a skewed shim shaft adapter fitting, a skewed shim shaft adapter fastener, and one or more annularly shaped skewed shims, sometimes called “cogs”, which have, circumferentially, a non-uniform thickness. The skewed shim shaft adapter fitting has a socket located in its distal end and a threaded hole in its proximal end. The hosel is accepting of a proximal portion of the skewed shaft adapter fitting and, in the case of a “single skewed shim” shaft adapter which has a single shim, or cog, the shim is placed between the fitting and the head's neck. In this type of shaft adapter, the head's indexing structure is typically embodied in the neck's distal end, and is herein called a neck indexing structure. The skewed shim has a shim indexing structure which has portions lying on both a distal side and a proximal side of the skewed shim, and the skewed shim shaft adapter fitting has a skewed shim shaft adapter fitting indexing structure. When this skewed shim shaft adapter is secured in the hosel by passing its fastener through a hole in the hosel's proximal end and engaging the threaded hole in the fitting, the portion of the shim indexing structure which lies on the shim's proximal side engages with the neck indexing structure to restrain rotation of the shim with respect to the neck in any one of a plurality of rotational positions of the shim with respect to the neck. The portion of the shim indexing structure which lies on the shim's distal side engages with the skewed shim shaft adapter fitting indexing structure to restrain rotation of the fitting with respect to the skewed shim in any one of a plurality of rotational positions of the fitting with respect to the skewed shim. Thereby, both the skewed shim shaft adapter fitting and the skewed shim are restrained from rotation with respect to the neck. Normally, adjustment of the skewed shim shaft adapter includes rotation of the skewed shim, or cog, but the fitting remains in a rotationally fixed position with respect to the neck. An example of a single skewed shim shaft adapter is shown in U.S. Pat. No. 8,535,173 to Golden and Harvell in which the head's indexing structure is a neck indexing structure which comprises a plurality of teeth embodied in the neck's distal end. The shim indexing structure and the skewed shim shaft adapter fitting indexing structure comprise a plurality of teeth located on the perimeter of the shim and the fitting.
A “double skewed shim” shaft adapter provides for more adjustments to a golf club's angular properties than those provided by the single skewed shim shaft adapter. The double skewed shim shaft adapter is similar to the single skewed shim shaft adapter except it has two skewed shims, a distal skewed shim, with a distal shim indexing structure, and a proximal skewed shim, with a proximal shim indexing structure. Both shim indexing structures have portions which lie on opposite sides, distal and proximal, of their respective skewed shims. When this double skewed shim shaft adapter is secured in the hosel, the fitting indexing structure, the distal shim indexing structure, the proximal shim indexing structure, and the head indexing structure are progressively engaged to restrain rotation of the shims and the fitting with respect to each other and with respect to the neck. Here again, in performing an adjustment, one or both shims are rotated with respect to the neck but the fitting typically remains rotationally fixed. An example of a double skewed shim shaft adapter is shown in U.S. Pat. No. 9,174,097 to Dacey et al.
Shaft adapters of both the elemental type and the skewed shim type are widely used in today's golf clubs, and both types have positive and negative features. The following discussions concerning the skewed shim type of shaft adapter pertain to, by way of example, the double skewed shim shaft adapter shown in U.S. Pat. No. 9,174,097 to Dacey et al. Discussions concerning the elemental type of shaft adapter pertain to, by way of example, the elemental shaft adapter shown in U.S. Pat. No. 8,303,431 to Beach et al.
Shaft adapters of the skewed shim type have some advantages over shaft adapters of the elemental type. As mentioned above, adjustment of shaft adapters of the skewed shim type typically normally precludes rotation of their fittings. This is a benefit because some people believe that, due to asymmetries in shafts, there is a preferred rotational orientation of the shaft with respect to a target line. When using a shaft adapter of the skewed shim type, the shaft can be placed in its preferred orientation and it remains in this orientation even after performing an adjustment. On the other hand, shaft adapters of the elemental type require rotation of their fitting to perform an adjustment, and therefore, consequently, a rotation of the shaft with potentially undesirable results. Also, shaft adapters of the skewed shim type are typically capable of independently adjusting a club's loft and lie angles. Shaft adapters of the elemental type, on the other hand, do not have this capability; rotation of the elemental shaft adapter's fitting concurrently adjusts the club's loft angle and its lie angle.
But shaft adapters of the skewed shim type have some disadvantages with respect to shaft adapters of the elemental type. One disadvantage is that shaft adapters of the skewed shim type typically are more massive than those of the elemental type, and this increased mass is, in general, undesirable. Shaft adapter mass reduces availability of what is called, in head construction, “discretionary mass”, which is mass that can be strategically located in the head to achieve a desired ball flight. Also, an increase in shaft adapter mass may require an undesirable offsetting reduction in shaft mass. Or, all other things being equal, increasing shaft adapter mass will increase the club's swingweight and overall weight, possibly limiting club head speed. A double skewed shim shaft adapter, constructed very similarly to the adapter shown in Dacey, has a mass, including its fastener, of 13.4 grams. An elemental shaft adapter, constructed very similarly to the adapter shown in Beach, has a mass, including its fastener, of 6.7 grams. Therefore, a club head with this double skewed shim shaft adapter attached will be more massive than the club head with this elemental shaft adapter attached.
Another disadvantage of shaft adapters of the skewed shim type is an inherent weakness in their connection to the head. Impact of the golf club's head with a golf ball exerts a force on the club, and this force has a magnitude larger than one would perhaps think. During impact, the golf ball is in contact with the head's face for approximately 350 microseconds. An accomplished golfer can attain ball speeds upwards of 240 kilometers/hour (150 miles/hour), and this speed, multiplied by the golf ball's mass of about 46 grams, is the ball's momentum after leaving the face. Under an assumption that the force during the 350 microsecond contact time is constant, this indicates that the force exerted on the ball by the club, or conversely the force exerted by the ball on the club, can be over 875 million dynes (2000 pounds). This force causes the club head to decelerate rapidly, and the shaft adapter and the shaft are also urged to decelerate rapidly due to their connection to the head. Additionally, the ball's impact location on the head's face is normally offset from the hosel axis (and the shaft axis), resulting in application of a torque on the shaft adapter about the hosel axis.
Referring to FIGS. 1 and 2 of Dacey, he says in column 4, lines 11-16 “The bore 25 must be large enough to permit the shaft sleeve 100 to move when the shims 30, 40 adjust the angle of a shaft with respect to the hosel 20 . . . ”. In other words, as shims 30 and 40 are rotated, the proximal end of sleeve 100 moves in a circular fashion in hosel 20. Therefore, sleeve 100 cannot have a close-fitting relationship with an inner surface of hosel 20. Also, a hole in flange 22 of hosel 20 through which fastener 60 passes must be significantly larger than a diameter of fastener 60 to allow fastener 60 to move in the hole as adjustments are made. As a result of an impact with a golf ball, a moment of force is applied to the shaft adapter about, for instance, the top of hosel 20 of Dacey. Fastener 60 applies a tension which urges sleeve 100 against shim 30, shim 30 against shim 40, and shim 40 against hosel 20, and this tension, applied to a torque arm having a length which is approximately a diameter of hosel 20, resists this moment. The moment of force can also be resisted by a frictional force which exists between fastener 60 and flange 22. But calculations show that, at a sufficiently high club head speed, impact of the head with the ball can exert a moment of force on the adapter which can overcome these two modes of resistance and allow some undesirable movement of shaft sleeve 100 in hosel 20. Also, the torque exerted on the shaft adapter due to ball impact is resisted by interlocking alignment features, or teeth, embodied in hosel 20, shims 30 and 40, and shaft sleeve 100. Therefore, in this double shim skewed shim shaft adapter, three interfaces resist this torque. Due to manufacturing tolerances, these three interfaces will allow some undesirable rotation of sleeve 100 with respect to hosel 20.
It is desirable to have a skewed shim shaft adapter and an elemental shaft adapter which are interchangeable in their connection to a golf club head, thus allowing for a first golf club head assembly comprising the head and the skewed shim shaft adapter, and a second golf club head assembly comprising the head and the elemental shaft adapter. This interchangeability provides for accessing benefits provided by the skewed shim shaft adapter or benefits provided by the elemental shaft adapter. In a particular case in which the head is manufactured to be fitted with the skewed shim shaft adapter, this interchangeability allows for the elemental shaft adapter to be retrofitted to the head.
Golf shaft adapters of two different types, a skewed shim shaft adapter and an elemental shaft adapter, are interchangeable in their connection to a head. These interchangeable shaft adapters are particularly useful in retrofitting the elemental shaft adapter to a head which is manufactured to be fitted with the skewed shim shaft adapter. An assemblage, comprising the head, the skewed shim shaft adapter, and the elemental shaft adapter, provides a technician a choice between a skewed shim shaft adapter and head assembly comprising the head and the skewed shim shaft adapter, or an elemental shaft adapter and head assembly comprising the head and the elemental shaft adapter. This assemblage allows the technician to choose the shaft adapter which provides more benefit to his customer.
Drawings of the invention are as follows:
Skewed shim shaft adapter and head assembly 1 represents prior art in that hosel 20, neck 22, neck indexing structure 24, and skewed shim shaft adapter 30 are similar to what is shown and described in Dacey. In this particular case, head 10 is manufactured to be fitted with skewed shim shaft adapter 30.
Although head 10 is manufactured to be fitted with skewed shim shaft adapter 30 to make skewed shim adapter and head assembly 1, elemental shaft adapter 130 is designed such that it can be retrofitted to head 10 to make elemental shaft adapter and head assembly 101. With skewed shim shaft adapter 30 removed from head 10, elemental shaft adapter 130 is retrofitted to head 10 by inserting elemental shaft adapter fitting 132 into hosel 20, inserting elemental shaft adapter fastener 138 through hole 28 in hosel 20, and engaging fastener 138 with elemental shaft adapter threaded hole 136. Elemental shaft adapter fitting indexing structure 150 is shown as having a construction which allows it to engage with neck indexing structure 24 in any one of four rotational positions with respect neck indexing structure 24 and neck 22. With elemental shaft adapter fitting 132 in a desired rotational position with respect to neck 22 which potentially provides for a desired effect on angular properties and which allows engagement of elemental shaft adapter fitting indexing structure 150 with neck indexing structure 24, elemental shaft adapter 130 is secured to head 10 by tightening fastener 138 in threaded hole 136. With elemental shaft adapter 130 thus secured to head 10, engagement of elemental shaft adapter fitting indexing structure 150 with neck indexing structure 24 restrains rotation of elemental shaft adapter fitting 132 with respect to neck 22. Using elemental shaft adapter socket 134, elemental shaft adapter 130 provides for shaft 5 to be secured to elemental shaft adapter fitting 132 and thus to head 10.
As indicated above, head 10 is manufactured to be fitted with a shaft adapter of the skewed shim type, namely skewed shim shaft adapter 30. But elemental shaft adapter 130, even though being a different type of shaft adapter, can be retrofitted to head 10 if constructed to be interchangeable with skewed shim shaft adapter 30. This interchangeability places some design constraints on elemental shaft adapter 130. For instance, elemental shaft adapter fitting 132 must be insertable in hosel 20 and elemental shaft adapter fastener 138 must be able to pass through hole 28 in hosel 20 sufficiently to engage elemental shaft adapter threaded hole 136. But perhaps most importantly, elemental shaft adapter fitting indexing structure 150 must be engageable with neck indexing structure 24 to restrain rotation of elemental shaft adapter fitting 132 with respect to neck 22.
Interchangeability of skewed shim shaft adapter 30 and elemental shaft adapter 130 does not, however, mean that some of their features must be identical. For instance, in skewed shim shaft adapter and head assembly 1, proximal skewed shim indexing structure 54 (the portion located on the proximal side of proximal skewed shim) engages with neck indexing structure 24. But interchangeability does not mean that elemental shaft adapter fitting indexing structure 150 must be identical in shape and size to that proximal portion of proximal skewed shim indexing structure 54. Elemental shaft adapter fitting indexing structure 150 just needs to be engageable with neck indexing structure 24 in a manner sufficient to restrain relative rotation between the two structures. Additionally, even though elemental shaft adapter 130 may be designed to allow elemental shaft adapter fastener 138 to be identical to skewed shim shaft adapter fastener 38, thus not requiring a separate fastener to be supplied when retrofitting, it may be desirable that elemental shaft adapter fastener 138 be different from skewed shim shaft adapter fastener 38. For instance, it may be desirable that elemental shaft adapter fastener 138 and skewed shim shaft adapter fastener 38 have different lengths or even different thread sizes and/or pitches.
Interchangeability also does not mean that a distance from a distal end of neck 22 to a distal end of skewed shim shaft adapter fitting 32 be identical, or even similar, to a distance from the distal end of neck 22 to a distal end of elemental shaft adapter fitting 132. Because distal skewed shim 40 and proximal skewed shim 42 are not present in elemental shaft adapter 130, the distal end of elemental shaft adapter fitting 132 can potentially be closer to the distal end of neck 22 than the distal end of skewed shim shaft adapter fitting 32. If this is adopted, this allows for elemental shaft adapter 130 to be significantly less massive than skewed shim shaft adapter 30. Mass reduction of 6 grams or more is achievable.
Previous discussions stated that skewed shim shaft adapter 30 is “fitted” to head 10, thereby making skewed shim shaft adapter and head assembly 1, and that elemental shaft adapter 130 is “retrofitted” to head 10, thereby making elemental shaft adapter and head assembly 101. Use of the words “fitted” and “retrofitted” imply a temporal priority of skewed shim shaft adapter and head assembly 1 relative to elemental shaft adapter and head assembly 101. This temporal priority exists if head 10 was originally manufactured to be exclusively fitted with skewed shim shaft adapter 30, and elemental shaft adapter 130 is subsequently provided in order to be retrofitted to head 10. But this temporal priority is not necessarily applicable in assemblage 200. A manufacturer can adopt this concept of interchangeability between shaft adapter types and initially design head 10, skewed shim shaft adapter 30, and elemental shaft adapter 130 in order that the shaft adapters can interchangeability be employed to provide for shaft attachment to head 10.
If a technician has assemblage 200 at his disposal, he can initially choose either shaft adapter to make either assembly depending on his customer's particular needs. For a less accomplished golfer who perhaps is not sure of the angular parameters he needs in his club, the technician might choose skewed shim shaft adapter 30 to make skewed shim shaft adapter and head assembly 1 in order to take advantage of the adjustment features of this skewed shim type of shaft adapter. This golfer also typically will have a lower swing speed, and the inherent weakness in the connection of skewed shim shaft adapter 30 to head 10 is therefore not as detrimental as it is for a more accomplished golfer with a higher swing speed. For the more accomplished golfer with the higher swing speed, the technician might choose elemental shaft adapter 130, thus making elemental shaft adapter and head assembly 101, thereby taking advantage of the connection rigidity of shaft adapter 130. Also, if elemental shaft adapter 130 is designed such that it is less massive than skewed shim shaft adapter 30, this allows the technician to provide more discretionary mass in head 10 or to increase shaft mass, both of which are important to the more accomplished golfer.
Accordingly, the reader will see that herein described are interchangeable shaft adapters of two different types, a skewed shim shaft adapter and an elemental shaft adapter. In a special case in which a head is manufactured to be fitted with the skewed shim shaft adapter, thereby making a skewed shim shaft adapter and head assembly, this interchangeability allows for the elemental shaft adapter to be retrofitted to the head, thereby making an elemental shaft adapter and head assembly. Also, an assemblage, comprising the head, the skewed shim shaft adapter, and the elemental shaft adapter, allows a technician to select the shaft adapter type which is more suitable for his customer.
Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of it. For instance, the elemental shaft adapter is described as potentially being less massive than the skewed shim shaft adapter, but in some cases it may be desirable that the two shaft adapters have substantially the same mass. Also, because the elemental shaft adapter does not contain any skewed shims, this allows for its distal end to be closer to the head's neck than a distance allowed by the skewed shim shaft adapter, but in some cases it may be desirable that the two shaft adapters have the same, or similar, distances from their distal ends to the head's neck. Also, the elemental shaft adapter can be either a straight axis elemental shaft adapter or a skewed axis elemental shaft adapter. The necks, fittings, and shims are shown as having indexing structures which allow them to engage with a corresponding indexing structure in any one of four relative rotational positions, but other numbers, such as two, six, or eight, are possible. The scope of the invention should be determined by the appended claims and their legal equivalents rather than by the examples given.
