DESC:FIELD OF INVENTION

The present invention relates to a fixture for dowel puller welding. In particular, the present invention relates to a fixture for dowel puller welding, which is used for removing dowel from the sheet metal dies and body welding fixtured. The present invention also relates to a process for making the die and welding fixture.

BACKGROUND OF THE INVENTION

Quite often, dowel pin is used for the positioning of die components. The position of the die components is determined by using dowel pin lightly press-fitted in two die components. The diameter of the dowel pin is determined according to the size of the die component, as in case of screws.

A dowel puller is used to remove the dowel from such dies or welding fixtures. There are different sizes of dowels and therefore different dowel pullers are required with different bolt welded to it according to the dowel size.

Conventional dowel puller is made of a rod having a bolt welded at its one of its ends and another end having a circular shape ring with 10 to 12 mm thickness. Bolts of different sizes (according to the dowel size) are required to be welded at one of its ends to remove the dowel from dies and fixtures. The dowels have different tapped hole sizes for pulling according to the dowel diameter.

PRIOR ART

CN103962776A discloses a welding fixture comprising a base, a reference piece, a clamping mechanism set and turnover clamping mechanisms. The reference piece is provided with a reference surface matched with the outer surface of a skin and is hinged to the base, the skin can be connected to the reference surface through at least two sets of positioning hinge pins and positioning pin holes, wherein the positioning hinge pins and the positioning pin holes are matched, one of the positioning hinge pins and the positioning pin holes are formed in the reference piece, and the other of the positioning hinge pins and the positioning pin holes are arranged on the skin. The clamping mechanism set is used for clamping the skin to the reference piece. The turnover clamping mechanisms are used for driving the reference piece to rotate relative to the base and clamping the reference piece fixedly connected with the skin to a framework, so that the corresponding welding surfaces of the skin and the framework can be attached conveniently. By the adoption of a two-pin and one-surface positioning mode, the reference piece is used as a reference system of the framework and used for detecting the assembly dimensions of the skin and the reference piece in the X, Z and Y directions and for judging whether the positioning accuracy between the skin and the reference piece meets the welding process requirements or not. If it meets these requirements, the reference piece is turned over, so that the corresponding welding positions of the skin and the framework can be attached, and therefore, welding and positioning accuracy, positioning efficiency as well as the quality of welding are improved.

CN104308432A discloses a novel welding and positioning tool comprising a bottom plate, a first side plate, a second side plate, two clamping devices and two positioning levers. The first side plate and the second side plate are fixed on the bottom plate and perpendicular to the same, the first side plate is perpendicular to the second side plate, each clamping device comprises a universal joint, a fixed connection rod, a clamping rod and a handle, one end of each universal joint is fixed to the bottom plate while the other end is connected to one end of the corresponding fixed connection rod, the other end of each fixed connection rod is provided with one handle, each clamping rod made of an elastic material is arranged on the corresponding fixed connection rod, and the positioning levers are fixed on the bottom plate. By the novel welding and positioning tool, two angle bars perpendicular to each other can be fixed firmly, not requiring to continue applying the force to the tool after the angle bars are fixed, and the tool cannot move reversely due to elasticity but can still clamp the angle bars firmly. Moreover, the movement is flexible, time can be saved, and the angle bars are fixed quickly.

US4595186A discloses a rotating welding fixture for holding a pipe fitting against a welding table so that socket welds can be fabricated in one continuous operation. A locking dowel is passed into an opening in the fitting and the fitting is locked between the table top and the dowel, so that the entire weld region is fully exposed to the welding rod. The table is rotatably supported in a base, so that the work can be turned past the welding rod, to complete the weld without having to break the weld bead. Rotating welding fixture holds the pipe fitting against a welding table, so that socket welds can be fabricated in one continuous operation.

However, the above mentioned various prior arts disclose various welding fixtures which are not accurate enough, which take longer time for welding and have proven to be unsafe to the operators, while performing such welding operations.

DISADVANTAGES WITH THE PRIOR ART

The conventional method of dowel puller welding leads to the following disadvantages:

- Time required for welding of bolt to dowel puller is high, i.e. about 6 minutes.

- Welding electrode consumption is high.

- Poor quality of welding obtained.

- Mismatched bolt and puller rod concentricity.

- Frequent breakage of the bolts due to this bolt and puller rod mismatch.

- Lower service life of puller due to poor welding quality.

- Unsafe working environment for personnel during welding operations.

- Minimum two persons are required for welding of bolt with dowel puller.

- Product quality is also affected due to eccentricity.

- Method of welding of bolt with dowel puller rod is less accurate.

- High operator skill necessary for such welding of bolt with dowel puller.

To address all these disadvantages of the conventional method taught by the prior art documents and methods, it is the need of the hour to propose and configure an improved fixture for dowel puller welding, which obviates the above disadvantages.

It is also necessary to devise an improved method which considerably increases the accuracy of the process of welding of bolt with the dowel puller rod and also significantly reduces the time for checking thereof.
OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a fixture for accurate welding of different sizes of bolts with dowel pullers.

Another object of the present invention is to provide a fixture for welding of different sizes of bolts with dowel pullers with better access of welding.

Still another object of the present invention is to provide a fixture for welding of different sizes of bolts with dowel pullers to eliminate the unsafe condition while doing welding.

Yet another object of the present invention is to provide a fixture for welding of different sizes of bolts with dowel pullers to reduce the defects occurs due to eccentricity of dowel pullers & bolts.

A further object of the present invention is to provide a method for welding of different sizes of bolts with dowel pullers which is very simple.

A still further object of the present invention is to provide a method for welding of different sizes of bolts with dowel pullers which is very operator friendly and safe.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a fixture for dowel puller welding in sheet metal dies, the fixture comprises:

• a main holding block having a plurality of holes for fixing the fixture on a surface;

• a pair of dowel puller bolt holders to be fastened on the main holding block by means of suitable fasteners;

• at least one dowel puller bolt;

• a locking plate for locking the dowel puller rod on the main holding block; and

• a wing bolt for tightening the locking plate on the main holding block for locking the dowel puller rod thereon;

wherein the main holding block is configured with a pair of mutually spaced apart V-notches made along the length on the upper face thereof, for accurately aligning the centers of the dowel puller rod and dowel puller bolt disposed in one of the V-notches.

Typically, at least three (3) holes of different sizes are provided on the main holding block for fitting the fixture on a flat surface.

Typically, each dowel puller bolt holder is provided with tapped holes of three (3) different sizes for welding bolts of different sizes on the dowel puller rod.

Typically, the tapped holes in the respective dowel puller bolt holders and the center line of V-notches are aligned in the same plane.

Typically, each dowel puller rod is bolted to the main holding block at a position for matching the center of the dowel puller bolt with the center of the dowel puller rod after mounting thereof in one of the two ‘V’ notches.

Typically, the fixture is preferably made of mild steel.

Typically, a plurality of threaded holes of different tap sizes is provided on both side faces of the main holding block for parking Allen bolts of standard sizes for tightening dowel puller holders on the main holding block.

Typically, ten (10) Allen bolts each are parked on either side of the main holding block, divided in two mutually spaced apart rows.
In accordance with the present invention, there is also provided a mild steel fixture for dowel puller welding in sheet metal dies, the fixture comprises:

• a main holding block having three (3) holes of different sizes provided for fixing the fixture on a flat surface;

• each dowel puller bolt holder is provided with successively concentrically tapped holes of three (3) different sizes for welding bolts of different sizes on the respective dowel puller rod;

• at least one dowel puller bolt;

• a locking plate for locking the dowel puller rod on the main holding block; and

• a wing bolt for tightening the locking plate on the main holding block for locking the dowel puller rod thereon;

• a plurality of threaded holes of different tap sizes is provided on both side faces of the main holding block for parking Allen bolts of standard sizes for tightening dowel puller holders on the main holding block.

• ten (10) Allen bolts each are parked on either side of the main holding block, divided in two mutually spaced apart rows;

wherein the main holding block is configured with a pair of mutually spaced apart V-notches made along the length on the upper face thereof, for accurately aligning the centers of the dowel puller rod and dowel puller bolt disposed in one of the V-notches.

Typically, the tapped hole in the respective dowel puller bolt holder and the respective dowel puller rod is fixed on the main holding block at a position for matching the center of the respective dowel puller bolt with the center of the dowel puller rod after mounting thereof in one of the two ‘V’ notches.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, wherein:

Figure 1 shows a conventional practice of welding done by two persons.

Figure 2 shows a perspective view of the fixture configured in accordance with the present invention for welding of different sizes of bolts held in dowel puller bolt holder.

Figure 3 shows a perspective view of the fixture of Fig.2 holding a bolt with dowel puller for subsequent welding thereof, seen from the rear/dowel puller bolt holder side.

Figure 4 shows a perspective view of the fixture of Fig.2 holding a bolt with dowel puller for subsequent welding thereof, seen from the front/main holding block side.

Figure 5 shows a perspective view of the fixture of Fig.2, seen from the front or dowel puller bolt holder side.

Figure 6 shows another perspective view of the fixture of Fig.2, seen from the rear or main holding block side.

Figure 7 shows a front-view of the fixture of Figures 2 to 6.

Figure 8 shows a top-view of the fixture of Figures 2 to 6.

Figure 9 shows a right-hand side view of the fixture of Figures 2 to 6.

Figure 10 shows a left-hand side view of the fixture of Figures 2 to 6.

Figure 11 shows a rear-view of the fixture of Figures 2 to 6.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, the fixture for welding of different sizes of bolts held in the dowel puller bolt holder configured in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1 shows a conventional practice of welding done by two persons, i.e. the operator Op1 and operator Op2. Operator Op1 holds the dowel puller rod 22 holding a bolt 24 to be welded by the operator Op2 holding the welding torch 26. This also requires a coordination between both the operators Op1 and Op2.

Figure 2 shows the fixture 20 configured in accordance with the present invention, for welding of different sizes of bolts 24 held in the dowel puller rod 22 (Figure 1). The fixture includes two ‘V’ notches 03, 04 in the main holding block 01 for locating the dowel puller rod 22. Three (3) numbers of holes 02 of different diameters are provided on the block 01 for fitting the fixture 20 on a flat surface by means of these holes 02. The dowel puller rod 22 is bolted to the block 01 at such a position that the center of the dowel puller bolt 24 matches the center of the dowel puller rod 22 after mounting it in one of the two ‘V’ notches 03, 04. A pair of dowel puller bolt holders 07 are also provided and each has three (3) different tapped holes 10 to weld different bolt sizes to the dowel puller rod 22. The dowel puller bolt holders 07 can be bolted in the main holding block 01 by means of Allen bolts 08 and also hold dowels 09 therein. A locking plate 05 is provided for fixing the dowel puller rod 22 and the bolt 24 to be welded. This locking plate 05 locks the dowel puller rod 22 by tightening a wing bolt 06 for both dowel puller rod diameters of 10 mm and 12 mm. In addition, a plurality of threaded parking holes 11 of different tap sizes are provided on the side face of the main holding block 01 for bolts 12 of standard sizes. The fixture is made from mild steel.

Figure 3 shows a perspective view of the fixture of Fig.2 holding a bolt 24 inserted in the dowel puller rod 22 for subsequent welding thereof, as seen from the rear side or dowel puller bolt holder 07 side. Here, the dowel puller rod 22 with the bolt 24 is located in the V-notch 03 (not visible) ready for welding.

Figure 4 shows a perspective view of the fixture of Fig.2 holding a bolt 24 inserted in the dowel puller rod 22 for subsequent welding thereof, as seen from the front/main holding block 01 side. Here also, the dowel puller rod 22 with the bolt 24 is located in the V-notch 03 (not visible) ready for welding.

Figure 5 shows a perspective view of the fixture of Fig.2, seen from the front/dowel puller bolt holder 07 side. The features shown here are similar to those of Fig.2.

Figure 6 shows another perspective view of the fixture of Fig.2, seen from the rear or main holding block side. The features shown here are similar to those of Fig.2.
Figure 7 shows a front view of the fixture of Figs. 2 to 6. The features shown here are similar to those of Fig.2.

Figure 8 shows a top view of the fixture of Figs. 2 to 6. Here, three (3) holes 02 of different sizes are clearly visible.

Figure 9 shows a right-hand side view of the fixture of Figs. 2 to 6. Here V-notches 03, 04 are clearly visible.

Figure 10 shows a left-hand side view of the fixture of Figs. 2 to 6. Ten (10) number of bolts 12 are visible here.

Figure 11 shows a rear-view of the fixture of Figs. 2 to 6. Ten (10) numbers of holes 11 for the corresponding ten (10) of bolts 12 are clearly visible here.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The fixture configured in accordance with the present invention has the following advantages:

- Welding time required for bolt to dowel puller rod is reduced by 3 minutes only.

- All NVAs (Non-value adding activities) involved during the welding method are totally eliminated.

- Only 1 operator is required for welding bolt to the dowel puller rod.
- Concentricity of bolt and tapper rod is ensured by using this fixture.

- Easy and accurate bolt welding on dowel puller rod by low-skilled operator.

- More user-friendly fixture for welding the bolt to the dowel puller rod.

- Increases the service life of the dowel puller, since bolt is welded to the dowel puller rod accurately and without eccentricity.

- Bolt breakage during dowel pulling operation is eliminated.
- Offers safer working condition to the operator during welding.

- Defect rate is significantly reduced.
- Productivity of dowel pulling operation is substantially increased.

- Enhances the operator’s moral.

- Reduces the operator’s fatigue.

The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. The description provided herein is purely by way of example and illustration.

Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention.

These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art and they will not therefore be discussed in significant detail.
The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

Also, any reference herein to the terms ‘left’ or ‘right, ‘up’ or ‘down, or ‘top’ or ‘bottom’ are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel.

Furthermore, the various components shown or described herein for any specific application of this invention can be widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. When referring to the figures, like parts are numbered the same in all of the figures. ,CLAIMS:We claim:

1. A fixture for dowel puller welding in sheet metal dies, the fixture comprises:

• a main holding block having a plurality of holes for fixing the fixture on a surface;

• a pair of dowel puller bolt holders to be fastened on the main holding block by means of suitable fasteners;

• at least one dowel puller bolt;

• a locking plate for locking the dowel puller rod on the main holding block; and

• a wing bolt for tightening the locking plate on the main holding block for locking the dowel puller rod thereon;

wherein the main holding block is configured with a pair of mutually spaced apart V-notches made along the length on the upper face thereof, for accurately aligning the centers of the dowel puller rod and dowel puller bolt disposed in one of the V-notches.

2. Fixture as claimed in claim 1, wherein at least three (3) holes of different sizes are provided on the main holding block for fitting the fixture on a flat surface.

3. Fixture as claimed in claim 1, wherein each dowel puller bolt holder is provided with tapped holes of three (3) different sizes for welding bolts of different sizes on the dowel puller rod.

4. Fixture as claimed in claim 1, wherein the tapped holes in the respective dowel puller bolt holders and the center line of V-notches are aligned in the same plane.

5. Fixture as claimed in claim 4, wherein each dowel puller rod is bolted to the main holding block at a position for matching the center of the dowel puller bolt with the center of the dowel puller rod after mounting thereof in one of the two ‘V’ notches.

6. Fixture as claimed in claim 1, wherein the fixture is preferably made of mild steel.

7. Fixture as claimed in claim 1, wherein a plurality of threaded holes of different tap sizes is provided on both side faces of the main holding block for parking Allen bolts of standard sizes for tightening dowel puller holders on the main holding block.

8. Fixture as claimed in claim 7, wherein ten (10) Allen bolts each are parked on either side of the main holding block, divided in two mutually spaced apart rows.

9. A mild steel fixture for dowel puller welding in sheet metal dies, the fixture comprises:

• a main holding block having three (3) holes of different sizes provided for fixing the fixture on a flat surface;

• each dowel puller bolt holder is provided with successively concentrically tapped holes of three (3) different sizes for welding bolts of different sizes on the respective dowel puller rod;

• at least one dowel puller bolt;

• a locking plate for locking the dowel puller rod on the main holding block; and

• a wing bolt for tightening the locking plate on the main holding block for locking the dowel puller rod thereon;

• a plurality of threaded holes of different tap sizes is provided on both side faces of the main holding block for parking Allen bolts of standard sizes for tightening dowel puller holders on the main holding block; and

• ten (10) Allen bolts each are parked on either side of the main holding block, divided in two mutually spaced apart rows;

wherein the main holding block is configured with a pair of mutually spaced apart V-notches made along the length on the upper face thereof, for accurately aligning the centers of the dowel puller rod and dowel puller bolt disposed in one of the V-notches.
10. Mild steel fixture as claimed in claim 9, wherein the tapped hole in the respective dowel puller bolt holder and the respective dowel puller rod are fixed on the main holding block at a position for matching the center of the respective dowel puller bolt with the center of the dowel puller rod after mounting thereof in one of the two ‘V’ notches.

Dated: this day of 30th July 2016. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT