1. Field of the Invention
The invention relates generally to a process for breaking ingots into individual charges for later processing. In another aspect, the invention relates to an apparatus for breaking an ingot into separate charges by scoring the ingot and breaking it with a press.
2. Description of the Related Art
Metals, including superalloys of titanium, nickel, and cobalt are commonly formed as ingots for storage or shipping and are later used to form a desired part, usually by melting and casting the ingot or a portion of the ingot. Ingots can be formed using a vacuum melt or air melt process which involves pouring a molten mass of material into an upstanding cylindrical mold where the material is allowed to cool. As the material cools in the mold, a density gradient forms due to gravity, where the ingot is denser near the bottom of the mold and less dense near the top. Further, a depression commonly referred to as a “pipe” forms at the top of the mold due to the uneven cooling of the material within the mold. Thus, ingots are often not homogeneous in composition or structure and, as well, multiple ingots are not homologous with respect to each other.
Superalloys are typically used in the formation of precision parts in the aerospace and medical industries, e.g., turbine blades and surgical implants. Typical exemplary superalloys carry trademarks such as Inconel®, Mar®, and Rene®. Ingots normally come from the mill in diameters ranging from 2″ to 20″ and in lengths up to four feet or more. When a particular amount of material is needed for a desired part, a portion of the ingot, commonly referred to as a charge, is separated from the ingot for further processing. The length of the charge is determined by the weight of material needed. Superalloys are very dense, often having a density of about 0.3 pounds per cubic inch.
It is known to form a charge from an ingot by using an abrasive blade or saw to cut the charge off of the ingot. In a variation of this process, an abrasive blade notches one side of the ingot at a desired charge length, and then a press is applied to the ingot to break it at the notch. However, the use of abrasive blades has proven undesirable for two reasons. First, a blade creates a kerf in the ingot equal to the thickness of the blade, and the material from the kerf is lost. Ingots of superalloy material are very costly and the cumulative cost of material lost to kerfs is high. Second, contaminants from the abrasive blade while cutting or notching can become lodged in the charge, especially if the charge is formed from the end of the ingot with a pipe. These contaminants may adversely affect the quality of the charge, and consequently, the quality of the final parts formed from the charge. Another problem arising from notching one side of the ingot is that the resulting break follows an indeterminate path through the ingot. Consequently the size of the charge may be more or less than desired for subsequent processing. If more, then material may have to be removed, resulting in further waste. If less, then a supplementary charge must be created, resulting in more processing time, if not more waste.
Another known process for forming a charge from an ingot involves breaking the ingot over an anvil where the ingot is positioned to contact a sharp point on the anvil at a desired charge length. The sharp point serves as a fulcrum over which the ingot is broken by a press. Yet another process for forming a charge from an ingot involves using a chevron to notch the ingot at the desired charge length and then impacting an end of the ingot to break off the charge at the notch. Both of these processes have the problem of an indeterminate break path on the charge, resulting in a charge having more or less material than needed for the desired part. If there is too much material, the excess material is typically removed from the break edge using a grinding operation, resulting in lost material and increased risk of contamination.
An efficient apparatus and process is needed for forming a charge that maximizes the amount of usable material per ingot and reduces the likelihood of contamination of the material.
An apparatus for scoring and breaking ingots into charges is provided. According to the invention, the apparatus comprises a scoring station and a breaking station. The scoring station has a scoring assembly to make a circumferential scoring groove in the ingot at a desired charge length. The breaking station has a hydraulic press to break the ingot at the scoring groove to form the charge. The apparatus can further include a control system to automatically control the apparatus. The ingot is positioned in the press between upper and lower reaction plates where the scoring groove is partially or fully over the lower reaction plate.
According to another aspect of the invention, a process for scoring and breaking ingots into charges is provided. The ingot is weighed at at least two points along the length of the ingot. The density of the ingot is calculated and used to determine a desired charge length needed for a given weight of material. A circumferential scoring is then made in the ingot at a desired charge length. Finally, the charge is broken from the ingot at the scoring.
In the drawings:
a is a top view of a first embodiment of a cutting tool insert for use with the scoring station from
b is a side view of the cutting tool insert shown in
c is a side view of an ingot with a scoring groove formed by the tool of
a is a top view of a second embodiment of a cutting tool insert for use with the scoring station from
b is a side view of the cutting tool insert shown in
c is a side view of an ingot with a scoring groove formed by the tool of
The loading station 16 comprises a base 20 supporting a rack 22 for retaining a supply of ingots 100 and for feeding the ingots to the scoring station 12. The loading station 16 further comprises a weighing assembly 24. The weighing assembly 24 has a pair of scales positioned to weigh both ends of the ingot. The weight information (preferably in digital form) is sent to the control system to calculate the density of the ingot, and this calculation is used to determine the length of charge needed for a given material weight. The material weight needed per charge can be inputted into the control system. Given the density and the needed weight, the control system can calculate the length of the charge necessary to fulfill the needed weight. While illustrated as being a part of the loading station 16, the weighing assembly 24 can alternately be a part of the scoring station 12 or it can be part of a separate station.
Referring additionally to
The retaining assembly 26 comprises a chuck 38 that is movable between an open position where an ingot 100 can move unimpeded through the scoring station 12 and a closed position where the ingot is clamped within the chuck 38. The chuck 38 is fully rotatable through 360° of movement and powered to cause an ingot clamped therein to rotate. The scoring assembly 28 comprises a tool holder and driver 40 having a cutting tool 42. The tool holder and driver 40 is movable between a disengaged position where the cutting tool 42 is not in contact with the ingot, and an engaged position where the cutting tool 42 contacts a surface of the ingot. When the tool holder and driver 40 is moved to the engaged position as the ingot 100 rotates with the chuck 38, the cutting tool 42 scores the ingot with a groove 102 to a predetermined groove depth. The groove depth is optimized to reduce the material lost from the ingot when cutting the groove. A preferred range of groove depth is 0.06″ to 0.500″, regardless of the diameter of the ingot. The groove depth can be preprogrammed into the control system of the apparatus 10. As the chuck 38 rotates, the material removed from the ingot is hot and oxidizes, rendering it unfit for immediate recycling. If the cutting area is rendered devoid of oxygen, as, for example, if it were flooded with an inert gas to displace oxygen in the work space, the removed material will come off in the form of uncontaminated chips that can be collected and readily recycled for later use.
A suitable cutting tool 42 for use with the tool holder and driver 40 is shown in
Another suitable cutting tool 48 is shown in
The control system will normally advance the ingot 100 to the correct position beneath the tool holder and driver 40 to make a scoring groove 102, 104 at the desired charge length. A position detector (not shown) can also be provided on the scoring station 12 and in communication with the control system to sense when the ingot 100 is properly positioned. When the ingot 100 is in the correct position beneath the tool holder and driver 40, the chuck 38 will move to the closed position and the scoring assembly 28 will move to the engaged position to make the scoring groove 102, 104. After the scoring groove is made, the ingot will be advanced to the correct position beneath the tool holder and driver 40 for making the next scoring groove at the desired charge length, of another charge is to be made. This cycle continues until the entire ingot has been scored for multiple charges.
After the scoring operation is complete, the ingot 100 is advanced to the breaking station 14. Referring now to
The hydraulic press 56 comprises a hydraulic assembly 64 operating a ram 66 for vertical movement. Preferably, the ram 66 operates at forces sufficient to fracture the largest diameter ingots. When moved vertically downward, a break pad 68 on the end of the ram 66 is positioned to contact the distal end 70 of the ingot 100 away from the scored groove 102, 104. The distal end 70 of the ingot 100 that is to be broken into a charge (i.e. the unclamped end of the ingot) is positioned over a movable charge support 78. The charge support 78 receives the charge after being broken from the ingot and then is moved by a hydraulic cylinder 80 to discharge the charge from the breaking station 14. The charge can be discharged to the transfer station 18, which can comprise a conveyor similar to the conveyor 30 for the notching station 12 or other suitable means for transporting the charges exiting the breaking station 14.
Looking now at
Looking again at
Looking now more closely at
When the break occurs, a huge shock is transmitted to the lower reaction plate 60 from the loading point 130 due to the large reaction load. Consequently, the reaction plates 58, 60, and especially the lower reaction plate 60, are preferably made of compressively resistant, shock resistant tough material that is not brittle. An exemplary material is S-7 steel with at least 54-56 Rockwell C hardness.
Often, the break face 152 of the charge 150 will be rough with sharp points 154. A potential problem with sharp points 154 on the break face 152 is that when the charge is later dropped into a crucible, the sharp points can interact with the surface of the crucible and contaminate the charge, compromising the purity of the finished product. Consequently, a finishing operation can be optionally performed after the charge 150 exits the breaking station 14 to remove the sharp points from the break face 152. The transfer station 18 can transport the charge 150 to a finishing station. The finishing station can comprise an apparatus for any desired finishing process that will remove or otherwise dull any sharp points from the break face 152 on the charge. One suitable finishing process is needle peening from a needle gun, where a cluster of steel or stainless steel needles repeatedly impacts the break face 152 of the charge 150 to blunt any sharp points. Suitable finishing processes will preferably avoid the possibility of contamination of the break face.
Looking now at
The loading point 140 becomes the fulcrum about which the load L generates the moment.
The ductility of the material forming the ingots 100 will also determine where on the charge portion 110 the loading force L is to be applied. Lower ductility suggests that the loading force L will be applied as heretofore shown, i.e., at the distal end 70 of the ingot 100. But a higher ductile material may require the loading force L to be applied inward of the distal end 70.
It can be seen that a process for scoring ingots and breaking them into individual charges according to the invention includes scoring the circumference of an ingot with a shallow groove and then breaking the ingot at the score line. This process can be accomplished with the apparatus 10. One or more ingots 100 are placed on the rack 22. The forwardmost ingot is advanced to the weighing station 24. The proper charge length for a desired weight of material is calculated by the control system from the information provided by the weighing station 24. Since the weighing station 24 has scales positioned at more than one point along the length of the ingot, the density of material at different points can be taken into account. Thus a single ingot 100 may be divided into charges of unequal lengths, but each having the same weight. The ingot 100 is then transferred to the conveyor 30, which advances the ingot to the scoring station 12. When the ingot 100 is correctly positioned within the scoring assembly 28 to make a score for the first charge, the chuck 38 will move to the closed position. The scoring assembly 28 then moves to the engaged position where the cutting tool 42 contacts the surface of the ingot to make an initial scoring groove 102 at a predetermined groove depth. The chuck 38 is then rotated 360° to extend the scoring groove circumferentially around the ingot. The cutting tool 42 is then moved away from the ingot to the disengaged position and the chuck 38 is opened. The ingot 100 is then advanced a length equal to the desired charge length, whereupon the chuck 38 closes and a second scoring groove 102 is made. This continues until the entire ingot 100 has been scored to define the charges to be broken off from the ingot. The ingot 100 is then advanced by the conveyor 30 to the breaking assembly 14. The detector determines when the ingot score line 106 reaches the correct position beneath the hydraulic press 56 for breaking the first charge from the ingot. When the ingot 100 is in the correct position with respect to the hydraulic press 56, the clamps 58, 60 are moved to the closed position. The hydraulic press 56 is then actuated whereby the ram break pad 68 bears against the distal end 70 of the ingot 100 to break off a charge 150. The charge 150 is received by the charge support 78, which moves to discharge the charge from the breaking station 14. The ingot 100 is released by the clamps 58, 60 and advanced such that the next score line 106 is correctly positioned beneath the hydraulic press 56. The cycle continues until the entire ingot 100 has been broken into charges 150. After exiting the breaking assembly 14, the charges 150 can optionally be transferred to a finishing station to smooth any sharp points on the break faces 152 of the charges 150.
The process and apparatus according to the invention offers several advantages over prior art processes and apparatuses. First, material lost during the creation of charges from an ingot is minimized. The groove depth can be optimized to minimize the amount of material cut from the ingot when the scoring groove is cut. Further, since a lathe is used to score the ingot, the material that is cut from the ingot comes off in chips that can be collected and recycled for later use. As well, the risk of contamination of the charge is reduced. By using a cutting tool made of a hard material, such as a silicon carbide, fiber-reinforced ceramic, to make a shallow groove, few particles from the cutting tool will be transferred to the ingot. Further, the apparatus is extremely efficient. The apparatus is fully automated and thus will save time and operating cost. The apparatus is adjustable to accommodate ingots of different diameters
While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit. For example, the ram break pad 68 need not be grooved or angled, but can be positioned to contact anywhere on the charge portion 110. But it will be apparent that the further away from the scored groove (120, 104) the ram break pad contacts the charge portion 110, the greater the moment about the loading point 130.
This application claims the benefit of U.S. provisional application Ser. No. 60/743,322, filed Feb. 20, 2006, which is incorporated herein in its entirety.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/US2007/062415 | 2/20/2007 | WO | 00 | 8/20/2008 |
Number | Date | Country | |
---|---|---|---|
60743322 | Feb 2006 | US |