The present disclosure relates to a dowel pin assembly, more particularly, relates to an expandable cylindrical dowel pin assembly having a cylindrical body and a grub screw.
BACKGROUND OF THE DISCLOSURE AND PRIOR ARTS
A dowel or dowel rod or dowel pin is typically a cylindrical rod like structure, usually made from metal or wood or plastic. Dowel pins are commonly used as structural reinforcements in cabinet making and other plethora of applications, including, but not limited to, axles, brackets used in wall mounting or wall hanging application, machine tools and furniture. The dowel pins are generally locking / alignment devices used to keep machine components in accurate alignment. They are also used as location guides for adjacent machine parts and to keep two sections of a punch and a die in alignment.
Conventional locking devices include dowel pins having cylindrical and taper dowel surfaces. Cylindrical dowel pins tend to slip in an axial direction, and thus locking in the axial direction becomes a challenge. To overcome the difficulties associated with the cylindrical dowel pins, taper dowel pins are introduced. But, these types of taper dowel pins require precise drilling which requires special type of drill/reamer to obtain a taper surface in the dowel pin. Thus, manufacturing a taper dowel pin becomes a costly and time consuming process.
One kind of dowel pin is disclosed in the U.S patent application no. US 2014/0112732 Al. The dowel pin disclosed in this application includes an expanding dowel rod structure for co-axially aligning two separate work pieces. This dowel pin includes a cylindrical sleeve and a thrust retainer in tapered shape. The cylindrical sleeve and the thrust retainer are required to be inserted inside holes of the work pieces for locking. This type of dowel pin includes a taper shaped hole in the cylindrical sleeve and therefore, requires a special type of drill for obtaining the taper shaped hole. Thus, manufacturing this type of dowel pin is both costly and time consuming process.

Another kind of locking pin includes a split type pin. But split type pins are also inefficient in axial locking, thus split type pins have a limited usage where less axial locking is required.
Further, disassembling or removal of a conventional dowel pin once it is inserted into a hole becomes difficult and sometimes the dowel pin gets damaged upon removal. Thus, the dowel pin once used cannot be re-used.
In light of the above and other limitations of the dowel pins, it is objectively desired to provide a dowel pin which gets locked efficiently in the axial direction without slipping. It is also desired to decrease the manufacturing cost of the dowel pin providing non-taper surface in the dowel pin such as to obviate the usage of special type of drilling tool. Further, it is desired to prevent damage of dowel pins during removal.
SUMMARY OF THE DISCLOSURE
The present disclosure provides a dowel pin assembly comprising a cylindrical body and a grub screw. The cylindrical body has a first end, a second end opposite to the first end, a cylindrical blind hole extending from the first end, the blind hole having internal threads and a closed end surface disposed transverse to an axis of the cylindrical body. A plurality of slits is provided on a portion of the cylindrical body longitudinally. The plurality of slits are adapted to allow expansion of the slit portion of the cylindrical body in a radial direction. The grub screw has a threaded outer surface, wherein threads of the grub screw are adapted to mesh with the threads of the blind hole of the cylindrical body for obtaining an axial movement of the grub screw inside the blind hole. The grub screw also has a first end surface configured to abut on the closed end surface of the cylindrical body. The threaded outer surface of the grub screw and the internally threaded cylindrical blind hole of the cylindrical body are non-tapered, and the first end surface of the grub screw has a dog end, wherein the grub screw is adapted to transfer axial and radial forces to the threads of the cylindrical body on tightening

the grub screw, thereby radially expanding the slit portions of the cylindrical body for locking the dowel pin assembly inside a locking portion of an object.
In an embodiment, the plurality of slits is provided up to a threaded length portion of the blind hole of the cylindrical body.
In an embodiment, each slit of the plurality of slits comprises a relief hole at an end of the threaded length portion of the blind hole.
In an embodiment, the dog end of the grub screw is one of a flat and a convex shape.
In an embodiment, the grub screw comprises a drive head at a second end surface.
In an embodiment, the grub screw is configured to be tightened or loosened inside the blind hole of the cylindrical body through the drive head.
In an embodiment, the cylindrical body is adapted to be inserted into the locking portion having one of a cylindrical, tapered and slotted shaped hole.
In an embodiment, the blind hole includes a non-threaded portion for a depth equal to or more than a length of the dog end of the grub screw.
In an embodiment, the second end of the cylindrical body has one of a flat, convex, conical and frusto-conical shape.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
FIG. 1 shows a sectional view of an object being locked or joined with a dowel
pin assembly, according to an embodiment of the present disclosure;
FIG. 2 shows a perspective quarter sectional view of the dowel pin assembly shown in FIG. 1;

FIG. 3a shows a perspective quarter sectional view of a cylindrical body of the dowel pin assembly shown in FIG. 2, according to an embodiment of the present disclosure;
FIG. 3b shows a magnified view of a cut-out portion of the cylindrical body shown in FIG. 3a, according to an embodiment of the present disclosure
FIG. 4 shows a perspective view of a grub screw of the dowel pin assembly shown in FIGS. 1- 3a, and 3b, according to an embodiment of the present disclosure;
FIGS. 5a and 5b shows front sectional views of the dowel pin assembly shown in FIGS. 1-2 illustrating forces, according to an embodiment of the present disclosure; and
FIG. 6 shows a magnified view of portion "A" shown in FIG. 1 in locking state, according to an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE DISCLOSURE WITH REFERENCE TO ACCOMPANYING DRAWINGS
Provided below is a non-limiting exemplary embodiment of the present invention and a reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts. Moreover, references to various elements described herein, are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. It may be noted that any reference to elements in the singular may also be construed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claim.

Referring to FIG. 1, which illustrates a sectional view an object (101) to be locked or joined with a dowel pin assembly (100), according to an exemplary embodiment of the present disclosure. The dowel pin assembly (100) illustrated in the figure can be a locking/fastening/alignment device used to keep machine components of machines, such as, but not limited to, milling and drilling machine parts in an accurate alignment. The dowel pin assembly (100) can also be used as location guides for adjacent machine parts and to keep locking portions (101a) (shown in FIG. 6) of an object (101) together in a locking state (not shown). In the illustrated embodiment, the object (101) is a furniture part, where two flat structures can be locked using the dowel pin assembly (100). However, the object (101) may include, but not limited to, a wall structure, and machine part.
In the illustrated embodiment, the locking portions (101a) of the object (101) includes cylindrical holes. In another embodiment, the holes in the locking portions (101a) of the object (101) may be of irregular shapes in which the dowel pin assembly (100) can be inserted for locking. The dowel pin assembly (100) includes a cylindrical body (102) and a grub screw (104) disposed inside the cylindrical body (102) (more clearly shown in FIG. 2-6).
FIG. 2 illustrates the dowel pin assembly (100) shown in FIG. 1. The dowel pin assembly (100) in the illustrated figure is in quarter sectional view and positioned in an upright manner. The dowel pin assembly (100) includes the cylindrical body (102). In an exemplary embodiment, the cylindrical body (102) can be a solid body. In another exemplary embodiment, the cylindrical body may be made as hollow thereby could reduce weight. In the illustrated embodiment, the cylindrical body includes a first end (106), a second end (108) opposite to the first end (106). The first end (106) and the second end (108) of the cylindrical body (102) are flat circular ends. In an embodiment, the second end (108) of the cylindrical body may have any one of a flat, convex, conical and frusto-conical shape. In an embodiment, the second end (108) of the cylindrical body (102) is flat, as illustrated in FIG. 2 and FIG. 3a. The cylindrical body (102) also comprise a cylindrical blind hole (110) extending from the first end (106). The blind hole

(110) is drilled from the first end (108) of the cylindrical body (102) up to a depth (Dl). The depth (Dl) of the blind hole (110) may be approximately 1/4* of entire length (LI) of the cylindrical body (102). The depth (Dl) of the blind hole (110) may also vary depending upon the expansion requirement. The blind hole (110) and the cylindrical body (102) are co-axial to each other and have the same axis (X-X1). The blind hole (110) of the cylindrical body (102) is drilled using a drill (not shown), which does not include any special type of taper drill/reamer for providing taper to the blind hole (110). Further, the drills (not shown) used for drilling the blind hole (110) may not require precise positioning of the drill, as required in drilling tapered holes.
The blind hole (110) of the cylindrical body (102) has internal threads (112) and a closed end surface (114) disposed transverse to the axis (X-X1) of the cylindrical body (102), as shown in FIG. 3b, which illustrates a cut-out portion (B) of the cylindrical body (102). The threads (112) of the blind hole (110) are provided up to a threaded portion (Tl) of the blind hole (110) (as shown in FIG. 3a), and the blind hole (110) also includes a non-threaded portion (T2). In another embodiment, the blind hole (110) may be fully threaded (not shown) without any non-threaded portion. The threads (112) of the blind hole may be, but not limited to, V-shaped, whit worth, trapezoidal, ACME or any shape known in the art. In an illustrated embodiment, the threads of the blind hole (110) are V-shaped.
The cylindrical body (102) also comprises a plurality of slits (116) provided on a portion (SI) of the cylindrical body (102) longitudinally. The term "slit" as used in the present disclosure, refers to a long, narrow cut in the cylindrical body (102), typically throughout the entire thickness of the cylindrical body (102). The plurality of slits (116) of the cylindrical body (102) comprises two or more slits (116) provided in a circular array on the first end (106) of the cylindrical body (102). In a preferred embodiment, the plurality of slits (116) comprises six slits (116). The slits (116) are formed by making cuts, which starts from the first end (106) and ends up to the portion (SI) of the cylindrical body (102). The portions (SI) of the cylindrical body (102) provided with slits (116) may be called slit

portions (SI). The slit portion (SI) may be equal to the threaded length (Tl) of the blind hole (110), i.e. the slits (116) are provided from the first end (106) of the cylindrical body (102) to a length equal to the threaded length (Tl) of the blind hole (110). The slits portion (SI) of the cylindrical body (102) is configured to expand in radial direction for locking the cylindrical body (102) of the dowel pin assembly (100). Each slit (116) of the plurality of slits (116) comprises a relief hole (118) at a closed end (119) of the slit (116). The closed ends (119) of the plurality of slits (116) are the ends of the slits which are proximal to the closed end surface (114) of the cylindrical body (102).
The term "relief hole" as used in the present disclosure, refers to a hole provided at an end of the slit/cut portion for relieving stress caused during bending moment of the slit/cut portions. The relief holes (118) are through holes provided at the end of the slit portion (SI) of the cylindrical body (102) transverse to the axis (X-X1) of the cylindrical body (102). Diameters of the relief holes (118) may be more than width of the slits (116). This provides relief in bending stress caused during expansion of the slit portions (116) when a grub screw (104) is tightened against the closed end surface (114) of the blind hole (110). The closed end surface (114) of the blind hole (110) is a flat surface at the end of the blind hole (114). The closed end surface (114) of the blind hold (110) is configured to abut a first end surface (120) of the grub screw (104). The term "grub screw" as used in the present disclosure, refers to a screw having threaded outer surface for securing the grub screw inside a threaded hole.
FIG. 4 illustrates a perspective view of the grub screw (104), according to an embodiment of the present disclosure. The grub screw (104) comprises threaded outer surface (122) and the first end surface (120). Threads (124) of the grub screw (104) are configured to mesh with the threads (112) of the blind hole (110) for obtaining an axial movement of the grub screw (104) inside the blind hole (110). The threads (124) of the grub screw (104) may be V-shaped, whit worth, trapezoidal, ACME or any shape as may be obvious to a skilled person. In a preferred embodiment, the threads (124) of the grub screw (104) are V-shaped.

The shape and size of the threads (124) of the grub screw (104) is in accordance with the shape and size of the threads (112) of the blind hole (110), such that a clearance between the threads (112, 124) may be provided. The clearance between the threads (112, 124) allows the expansion of the slits portions (SI) of the cylindrical body (102) when the first end surface (120) of the grub screw (104) pushes the closed end surface (114) of the blind hole (110).
The first end surface (120) of the grub screw (104) has a dog end (121). The term "dog end" as used in the present disclosure, refers to an end with cylindrical tips having reduced diameter and having flat/curved surface. The dog end (121) of the grub screw (104) is configured to provide a clearance between the blind hole (110) and the grub screw (104). The dog end (121) provided up to a dog length (DL1). In an embodiment, the non-threaded portion (T2) of the blind hole (110) is provided up to a length equal to or more than the dog length (DL1) of the grub screw. The dog end (121) of the grub screw (104) may be one of a flat and convex shape. In a preferred embodiment, as illustrated in FIG. 2 and FIG. 5a, the dog end (121) is of convex shape. In one embodiment, as illustrated in FIG. 5b, the dog end (121) is of flat shape. The grub screw (104) also comprises a second end surface (126) opposite to the dog end (121). A drive head (128) is provided at the second end surface (126) of the grub screw (104) for tightening or loosening the grub screw (104) inside the blind hole (110) of the cylindrical body (102). The term "drive head" as used in the present disclosure, refers to a socket/ groove on a surface of a screw through which a driving tool is inserted for driving the screw. The drive head (128) may include socket shaped in one of a hexagon, square, star, slot, triangle and any other shape as may be obvious to a skilled person. In a preferred embodiment, the drive head (128) includes a socket of hexagonal shape. The grub screw (104) is configured to be inserted inside the blind hole (110) of the cylindrical body (102) such that the first end surface (120) of the grub screw (104) abuts on the closed end surface (114) of the cylindrical body (102). The grub screw (104) is then tightened against the closed end surface (114) of the cylindrical body (102) using a driving tool (not shown) inside the drive head (128)

of the grub screw (104). The tightening of the grub screw (104) transfer a force (Fl) on the threads (112) of the cylindrical body.
FIG. 5a and 5b illustrate a sectional front view of the dowel pin assembly (100) illustrating force (Fl) and its components. On tightening the grub screw (104), when the first end surface (120) of the grub screw (104) abuts the closed end surface (114) of the blind hole (110), the threads (124) of the grub screw (104) exert the force (Fl) on the threads (112) of the blind hole (110) of cylindrical body (102). This force (Fl) has a radial component (Fr) in the radial direction and an axial components (Fa) in the axial direction. The radial component (Fr) of the force (Fl) expands the slit portions (SI) of the cylindrical body (102) and the axial component (Fa) of the force (Fl) is equal to force of friction, which locks the grub screw (104) inside the blind hole (110) of the cylindrical body (102). As a result of expansion of the slit portion (SI) of the cylindrical body (102), the dowel pin assembly (100) is expanded and locked inside a locking portion (101a) of an object (101).
FIG. 6 illustrates magnified view of the portion (A) of the dowel pin assembly (100) shown in FIG.l in locking state. The dowel pin assembly (100) is locked inside the locking portion (101a) of the object (101). In the illustrated FIG. 6, the slit portions (SI) of the cylindrical body (102) moves radially outward, causing the cylindrical body (102) to be in frictional contact with the locking portion (101a) of the object (101) to be locked. The frictional force between the cylindrical body (102) and the locking portion (101a) of the object (101) locks the cylindrical body (102) inside the locking portion (101a) of the object (101). The locking portion (101a) of the object (101) may have shapes including, but not limited to, a cylindrical, tapered, and slotted shaped hole. The dowel pin assembly (100) locked inside the locking portion (101a) of the object (101) may be configured to be unlocked and removed from the locking portion (101a) of the object (101).

In an instance, when the dowel pin assembly (100) is required to be removed from the locking portion (101a) of the object (101), the grub screw (104) of the dowel pin assembly (100) is loosened by rotating the grub screw (104) in an opposite direction. The grub screw (104) is configured to be loosened by using the driving tool (not shown) inside the drive head (128) of the grub screw (104). On loosening, the threads (124, 112) of the grub screw (104) and the cylindrical body (102) get free from radial and axial forces (Fr, Fa) and thus the slit portions (SI) of the cylindrical body (102) regains its original cylindrical shape without any expansion in the slit portion (SI). Thus, the frictional force between the cylindrical body (102) and the locking portion (101a) of the object (101) decreases and the cylindrical body (102) is free to move inside the locking portion (101a) for removal of the dowel pin assembly (100).
Advantages
In an embodiment, the dowel pin assembly (100) is efficient in axial locking without using a tapered surface/body as compared with the existing dowel/split pins. Thus, cost involved in manufacturing the dowel pin assembly is less and the manufacturing requires less precise drilling as compared with the manufacturing of the existing dowel/split pins. Therefore, the dowel pin assembly (100) is cost effective as compared with the existing dowel pins.
In an embodiment, the dowel pin assembly (100) is configured to be locked and unlocked inside the locking portion (101a) of the object (101) without causing any damage or distortion to the cylindrical body (102) or the grub screw (104). Thus, the dowel pin assembly (100), according to the present disclosure, has better re-usability when compared with the existing dowel pins.
In an embodiment, the plurality of slits (116) is provided up to the threaded length portion (Tl) of the blind hole (110). The advantage of providing slits (116) up to the threaded length portion (Tl) is that a corner relief is not required to be provided at edge of the blind hole (110) for preventing the stress concentration at

the edge of the blind hole (110). Thus, preventing the cost of providing edge relief inside the blind hole (110).
In an embodiment, the each slit (116) of the plurality of slits (116) comprises the relief hole (118) at the end of the threaded length portion (Tl) of the blind hole (110). The advantage of providing the relief hole (118) is that the relief hole (118) reduce the stress concentration at the end of the each slit (116). In an embodiment, the dog end (121) of the grub screw (104) is one of a flat and a convex shape. The advantage of providing a flat or convex shaped end is that the flat or convex end may be more efficiently abut and exert force on the closed end surface (114) of the blind hole (110) as compared with other shaped end such as conical end, which may penetrate the closed end surface (114) of the blind hole (110) on tightening the grub screw (104).
In an embodiment, the grub screw (104) comprises the drive head (128) at the second end surface (126) for inserting the driving tool (not shown). The advantage of providing the drive head (128) in the grub screw (104) is that the grub screw (104) can be easily tightened or loosened inside the blind hole (110) of the cylindrical body (102) without causing any distortion to the grub screw (104) or the cylindrical body (102).
In an embodiment, the cylindrical body (102) is adapted to be inserted into the locking portion (101a) of the object (101). The advantage of providing cylindrical body (102) is that the cylindrical body (102) can be inserted in different shaped holes including cylindrical, tapered and slotted hole for locking.
In an embodiment, the second end (108) of the cylindrical body (102) has one of a flat, convex, conical and frusto-conical shape. The advantage of providing the second end (108) of the cylindrical body (102) in different shapes is that the cylindrical body (102) can be inserted into a body having different shaped ends.

Industrial Applicability
The disclosed dowel pin assembly finds its potential application in machineries, wall mounted structures and furniture industries. The dowel pin assembly can be used for alignment/ locking/ fixing one or more components in proper alignment and locking state. The dowel pin assembly may also be used as a positioning or locating device for locating various points on a component/machine parts. The dowel pin assembly as disclosed also finds its application where efficient axial locking is required, such as in automotive, aerospace and manufacturing industries. Further, the dowel pin assembly also finds its application where the re¬usability of the dowel pin is required.
While aspects of the present invention have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by modification of the disclosed device without departing from the scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present invention as determined based upon claims and any equivalents thereof.
List of referral numerals:
100: Dowel pin assembly
101: Object
101a: Locking portion of the obj ect
102: Cylindrical body
104: Grub screw
106: First end of the cylindrical body
108: Second end of the cylindrical body
110: Blind hole of the cylindrical body
112: Threads of the blind hole of the cylindrical body
114: Closed end surface of the blind hole of the cylindrical body
116: Plurality of slits of the cylindrical body
118: Relief hole of the cylindrical body

119: Closed end of the slits
120: First end surface
121: Dog end of the grub screw
122: Threaded outer surface of the grub screw
124: Threads of the grub screw
126: Second end surface of the grub screw
128: Drive head of the grub screw
A: Magnified portion of cylindrical body
B: Cut-out portion of the cylindrical body
LI: Length of the cylindrical body
D1: Depth of the blind hole of the cylindrical body
Tl: Threaded length of the blind hole of the cylindrical body
T2: Non-threaded portion of the blind hole of the cylindrical body
S1: Slit portion of the cylindrical body
DL1: Dog length of the grub screw
X-X1: Axis of cylindrical body/ blind hole
F1: Force on thread
Fa: Axial component of the force Fl
Fr: Radial component of the force Fl

We Claim:

1.A dowel pin assembly (100) comprising:
a cylindrical body (102) having a first end (106), a second end (108) opposite to the first end (106), a cylindrical blind hole (110) extending from the first end (106), the blind hole (110) having internal threads (112) and a closed end surface (114) disposed transverse to an axis (X-X1) of the cylindrical body (102), and a plurality of slits (116) being provided on a portion (SI) of the cylindrical body (102) longitudinally, the plurality of slits (116) adapted to allow expansion of the slit portion (SI) of the cylindrical body (102) in a radial direction; and
a grub screw (104) having a threaded outer surface (122), wherein threads (124) of the grub screw (104) are adapted to mesh with the threads (112) of the blind hole (110) of the cylindrical body (102) for obtaining an axial movement of the grub screw (104) inside the blind hole (110), and a first end surface (120) configured to abut on the closed end surface (114) of the cylindrical body (102), characterized in that
the threaded outer surface (122) of the grub screw (104) and the internally threaded cylindrical blind hole (110) of the cylindrical body (102) are non-tapered, and the first end surface (120) of the grub screw (104) has a dog end (121), wherein the grub screw (104) is adapted to transfer axial and radial forces (Fa, Fr) to the threads (112) of the cylindrical body (102) on tightening the grub screw (104), thereby radially expanding the slit portions (SI) of the cylindrical body (102) for locking the dowel pin assembly (100) inside a locking portion (101a) of an object (101).
2. The dowel pin assembly (100) as claimed in claim 1, wherein the plurality of
slits (116) is provided up to a threaded length portion (Tl) of the blind hole
(110) of the cylindrical body (102).

3. The dowel pin assembly (100) as claimed in any one of claims 1 and 2, wherein each slit (116) of the plurality of slits (116) comprises a relief hole (118) at an end of the threaded length portion (Tl) of the blind hole (110).
4. The dowel pin assembly (100) as claimed in any one of claims 1-3, wherein the dog end (121) of the grub screw (104) is one of a flat and a convex shape.
5. The dowel pin assembly (100) as claimed in any one of claims 1-4, wherein the grub screw (104) comprises a drive head (128) at a second end surface (126).
6. The dowel pin assembly (100) as claimed in claim 5, wherein the grub screw (104) is configured to be tightened or loosened inside the blind hole (110) of the cylindrical body (102) through the drive head (128).
7. The dowel pin assembly (100) as claimed in any one of claims 1-6, wherein the cylindrical body (102) is adapted to be inserted into the locking portion (101a) having one of a cylindrical, tapered and slotted shaped hole.
8. The dowel pin assembly (100) as claimed in any one of claims 1-7, wherein the blind hole (110) includes a non-threaded portion (T2) for a depth equal to or more than a length (DL1) of the dog end (121) of the grub screw (104).
9. The dowel pin assembly (100) as claimed in claim 1, wherein the second end (108) of the cylindrical body (102) has one of a flat, convex, conical and frusto-conical shape.