BACKGROUND

Field

The present disclosure relates to handles for assembling and positioning molds to create exothermic welds. In particular, the present disclosure describes a handle that is adjusted to engage with different configurations of exothermic mold components. The present disclosure further describes a handle that connects with mold components using spring-driven connectors

Description of the Related Art

Exothermic molding is a technique for joining metal objects, such as electrical conductors, using a highly exothermic chemical reaction. Welds created using this technique are mechanically strong and provide a secure, low resistance electrical connection between the objects. Such welds may be useful for lightning arrestors, grounding connections for electrical utility equipment, and the like.

Exothermic welding uses a powdered reaction mixture held in the reaction chamber of a mold. When the mixture is ignited it produces a molten metal. The molten metal flows from the reaction chamber into a mold cavity. Objects to be welded are positioned in the mold cavity. The molten metal wets the objects and fills the mold cavity. When the metal cools and solidifies the mold is removed, leaving the finished molded joint. Exothermic welding relies on a chemical reaction, for example, between copper oxide and powdered aluminum, that results in molten copper. Such reactions can reach temperatures in excess of 4000° F. Molds are typically made of refractory materials, such as ceramic or graphite, that can withstand these temperatures.

Molds are shaped to allow conductors with varying sizes, shapes, and configurations to be positioned in the mold cavity. Once the conductors are welded together, the mold needs to be removed from around the newly created joint. The configuration of conductors may be such that portions of the mold need to be separated from one another to release the conductors and welded joint from the mold.

One way to provide a mold that can be removed from welded conductors is to use a single shot mold. A single shot mold is formed from a heat-resistant ceramic body with a reaction chamber that holds the reactant mixture and is positioned above a mold cavity that is shaped to form a welded joint. The mixture is ignited and the resultant liquid metal flows into a cavity surrounding the conductors to create the joint. The ceramic mold is then broken away, releasing the welded conductors. Because the single shot molds are broken away once the weld is complete, they can be formed from a single piece of material and do not require separable sections to release the welded conductors. Single shot molds may be relatively expensive to use since a new mold is required each time a weld is made.

SUMMARY

The present disclosure relates to apparatuses and methods to address these difficulties.

An alternative to using single shot molds is to use a reusable mold. A reusable mold is formed from separable sections that have faces shaped to form a mold cavity and to hold the conductors in the proper configuration to form the welded joint. The mold sections are clamped together to form a mold cavity around the conductors. A reactant chamber above the mold cavity is filled with the reactant mixture and ignited, delivering molten metal to the mold cavity to create the weld. When the weld is complete, the mold sections are separated, allowing the mold sections to be removed intact from the welded conductors and reused.

To hold faces of the mold sections together and to position the mold with respect to conductors, a handle clamp is used. The handle clamp has rods that fit into holes in the mold sections to apply force to close and open the mold. The handle clamp has a locking mechanism to hold the mold closed while the weld is created. The handle clamp has mounting brackets fitted to the rods to secure the mold sections onto the rods. The mounting brackets each include a thumb bolt that is threaded through the bracket. To secure a mold section to the handle clamp, the installer fits the mold section over the rods and tightens the thumb bolts to engage with stabilizer holes on the mold section.

Molds may be designed with mold sections that separate from one another along a plane, for example, along a horizontal or vertical plane. The handle clamp is adjusted to accommodate different mold designs by rotating the mounting brackets about the rods so that the thumb bolts engage with the correct surface of the mold sections and so that the brackets do not interfere with the insertion of the rods into the mold sections.

Adjusting a handle clamp and connecting it with different configurations of mold may be cumbersome, particularly when the mold is used to create multiple welds and may be hot as a result of a previous molding operation. Because mounting bracket can rotate with respect to the rods, the brackets may inadvertently interfere with insertion of the rods into the mold sections. The installer may have to hold the brackets in place while at the same time inserting the rods into the mold sections to assure that the rods are fully inserted into the mold sections. In addition, to make sure the thumb bolts properly engage with stabilizer holes on the mold, the installer must hold the brackets in the correct position while turning the thumb bolts.

One aspect of the disclosure describes a handle clamp for an exothermic mold that includes mounting brackets that can be removably fixed into selected orientations. This allows the installer to set the configuration of the handle to accommodate a selected type of mold so that the rods can be fully inserted into the mold without having to manually hold the brackets in place. This also simplifies the task of tightening the thumb bolts to engage with mold sections because the selected positions of the brackets assure proper alignment of the thumb bolts with stabilizer holes.

According to another aspect of the disclosure, brackets are provided with a detent mechanism that fixes the bracket in either a parallel or perpendicular orientation with respect to the handle. The bracket has a plurality of holes on the surface facing the handle. The handle has a post or convex portion extending toward the bracket. The locations of the holes on the bracket are selected so that engagement of a selected hole with the post fixes the bracket into one of a plurality of the desired angular positions about the rod. A spring presses the bracket toward the surface of the handle, keeping the hole and post engaged with one another and holding the bracket in the selected angular position. Before connecting a selected exothermic mold with the handle, an installer puts the brackets in the proper positions to hold the sections of the selected mold. The rods are inserted into corresponding holes on the mold. When the rods are fully inserted into the mold, the brackets align with stabilizer holes on the mold. The installer fixes the mold to the handle by tightening the thumb bolts to engage the stabilizer holes.

When another configuration of mold is required, the installer adjusts one or more of the brackets so that a different hole on the bracket engages with the post on the handle clamp. The detent arrangement holds the bracket in the newly selected position while the installer fits the new mold sections over the rods and tightens the thumb bolts to fix the handle clamp with the new mold.

According to a further aspect of the disclosure, instead of thumb bolts, a handle clamp is disclosed that includes spring-driven bolts that engage with stabilizer holes on the mold sections. One or more brackets include a hole through which the bolt is inserted. A retaining ring is affixed to the bolt and a coil spring is disposed between the retaining ring and a distal surface of the bracket. The spring provides a biasing force that drives the bolt toward a mold section fitted to the handle. The distal end of the bolt engages a stabilizer hole on the mold section preventing the mold section from disengaging from the handle.

The bolt includes one or more protrusions or keys extending radially outward from the surface of the bolt. The hole in the bracket includes a slot through which the protrusion or key can fit, provided the bolt is angularly oriented so the protrusion or key is aligned with the slot. To disengage a mold section from the handle, an installer rotates the bolt until the protrusion or key aligns with the slot and pulls the bolt in the proximal direction until the protrusion or key is proximal of the bracket. The installer rotates the bolt so the protrusion or key is no longer aligned with the slot and releases the bolt, which moves distally under the bias force exerted by the spring. This brings the protrusion or key in contact with the proximal surface of the bracket, securely holding the distal tip of the bolt away from the mold section so that it does not interfere with the installation of a new mold section. To engage a new mold section with the handle, the installer rotates the bolt so that the key or protrusion aligns with the slot, allowing the bolt to move toward the mold section under the biasing force of the spring. The tip of the bolt engages with the corresponding stabilizer hole on the mold section. The installer then rotates the bolt so that the key or protrusion no longer aligns with the slot and the proximal end of the key or protrusion contacts the distal surface of the bracket, preventing the bolt from moving away from the mold section and assuring that the engagement of the bolt in the mounting hole is secure.

According to a further aspect of the disclosure there is provided a handle clamp for an exothermic mold comprising a pair of grips, a pair of legs connected with respective ones of the grips, the legs arranged to move toward and away from one another in response to motion of the grips. a plurality of engagement rods disposed on each of the legs, wherein the engagement rods on each leg are adapted to engage with respective sections of an exothermic mold, one or more brackets, each bracket rotatably disposed on one of the rods, and a detent mechanism to releasably hold the bracket in a selected angular position with respect to the rod.

According to a further aspect of the disclosure the detent mechanism comprises a convex feature and a plurality of concave features arranged radially about the engagement rod, the convex feature disposed on the leg or the bracket and the concave features disposed on the other of the leg or the bracket, the concave and convex features shaped to engage with one another and positioned so that when a selected one of the concave features is engaged with the convex feature, the bracket is positioned in a respective one of a plurality of angular positions about the rod. The detent mechanism further comprises a force applying member adapted to apply a force to hold the engaged convex and concave features against one another. The force applying member is one of a coil spring, a spring washer, an elastomeric washer, and a magnetic insert.

According to a further aspect of the disclosure the concave feature is a hole or dimple on the leg or bracket. According to a further aspect of the disclosure the convex feature is a pin extending from one of the leg or bracket and the concave feature is a hole in the other of the leg or bracket.

According to a further aspect of the disclosure the handle clamp further comprises a locking mechanism, the locking mechanism releasably locking the grips in a closed position.

According to a further aspect of the disclosure the handle clamp further comprises a bolt hole through the bracket and a bolt disposed in the bolt hole and movable toward and away from a surface of the mold and wherein the bolt and the bolt hole are in threaded engagement with one another. The bolt hole further comprises a key slot, wherein the bolt further comprises a key, wherein the bolt is rotatable in the hole and wherein, when the key is aligned with the key slot, the bolt can slide through the bolt hole. According to a further aspect of the disclosure a proximal end of the key engages a distal surface of the bracket when a tip of the bolt engages with the mold section. The bolt comprises a bolt-driving spring arranged to bias the bolt in a direction toward or away from the mold, wherein the bolt further comprises a spring retaining feature, and wherein the coils spring is disposed between a surface of the bracket and the spring retaining feature.

According to a further aspect of the disclosure the bolt further comprises a threaded portion adapted for threaded engagement with a threaded hole of the mold section. According to a further aspect of the disclosure the threaded portion of the bolt is provided only on a proximal portion of the bolt.

According to a further aspect of the disclosure there is provided a method for forming a weld comprising the steps of: providing an exothermic mold formed from a plurality of mold sections wherein the mold sections comprise rod engaging holes, stabilizer holes, and a mold cavity; providing a handle clamp, the handle clamp comprising: a pair of grips, a pair of legs connected with respective ones of the grips, the legs arranged to move toward and away from one another in response to motion of the grips, a plurality of engagement rods disposed on each of the legs, wherein the engagement rods on each leg are adapted to be inserted into engaging holes of respective sections of the mold, one or more brackets rotatably disposed on respective ones of the rods, wherein the bracket comprises a bolt hole, a bolt movably disposed in the bolt hole, and a detent mechanism to releasably hold the bracket in a selected angular position with respect to the rod; positioning the bracket in the selected angular position; engaging the detent mechanism to hold the bracket in the selected angular position; fitting the engagement rods into the rod engagement holes of the mold sections; extending the bolt through the bolt hole toward the mold section; engaging a tip of the bolt with a respective stabilizer hole of the mold section; positioning the mold sections adjacent a structure to be welded; squeezing the grips to press the mold sections together; activating an exothermic reaction in the mold to form the weld in the mold cavity; separating the grips to separate the mold sections; and removing the weld from the mold cavity.

According to a further aspect of the disclosure the bolt and bolt hole comprise mutually engaged threads and the step of extending comprises rotating the bolt.

According to a further aspect of the disclosure the handle clamp further comprises a spring connected with the bolt and the step of extending comprises biasing the bolt into engagement with the mold section with a biasing force applied by the spring. The bolt further comprises a key, the bolt hole further comprises a key slot, and the step of moving further comprises rotating the bolt to align the key with the key slot to allow the bolt to move through the bolt hole. After the tip is engaged with the stabilizer hole, the step of extending comprises rotating the bolt to misalign the key and the key slot to prevent the bolt tip from moving away from the stabilizer hole.

