Nordberg Inc. v. Telsmith, Inc.

• Decision Date: 29 March 1995
• Docket Number: No. 90-C-555.,90-C-555.
• Citation: 881 F. Supp. 1252
• Parties: NORDBERG INC., Plaintiff, v. TELSMITH, INC., Defendant.
• Court: U.S. District Court — Eastern District of Wisconsin

881 F. Supp. 1252

NORDBERG INC., Plaintiff, v. TELSMITH, INC., Defendant.

No. 90-C-555.

United States District Court, E.D. Wisconsin.

March 29, 1995.

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James E. Braza, Davis & Kuelthau, Milwaukee, WI, Lawrence J. Crain and Roger D. Greer, Greer, Burns & Crain, Ltd., Chicago, IL, for plaintiff.

Andrew J. Nilles, James E. Nilles, Nilles & Nilles, Milwaukee, WI, Richard W. Bethea, Jr. and Arthur P. Brock, Stophel & Stophel, Chattanooga, TN, for defendant.

DECISION AND ORDER

RANDA, District Judge.

This patent infringement case comes before the Court for decision after a three-week court trial. The Court has carefully considered all of the trial testimony and exhibits, the entire pretrial record, the parties' post-trial findings of fact and conclusions of law and the parties' post-trial briefing. Based on this review, the Court finds the patent claims-in-suit invalid. The Court further finds that, with the exception of two machines, one sold and one not sold, the claims-in-suit are not infringed, either literally or under the doctrine of equivalents, by the accused machines.

FINDINGS OF FACT¹

I. PARTIES AND CLAIMS

1. The plaintiff, Nordberg Inc. ("Nordberg"), is a Delaware corporation with its principal place of business located in Milwaukee, Wisconsin. Nordberg manufactures and sells machinery used in mining and mineral aggregate production. This machinery includes rock crushers, which form the subject matter of the patent in suit. (Nordberg Findings of Fact ("NFOF") at ¶¶ 1, 3; Telsmith Findings of Fact ("TFOF") at ¶ 1; Trial Transcript ("TT"), Vol. 1 at 13-14.)

2. The defendant, Telsmith, Inc. ("Telsmith"), is a Delaware corporation with its principal place of business located in Mequon, Wisconsin. Telsmith also manufactures and sells machinery used in mining and mineral aggregate production, including rock crushers. (NFOF at ¶¶ 2, 5; TFOF at ¶ 2; TT, Vol. 2 at 289-90.)

3. Nordberg and Telsmith are among four major manufacturers competing in the market for conical crushers. Nordberg has been in the market since the 1920's and is the number one supplier of cone crushers in the world with over 16,000 installations worldwide. (NFOF at ¶¶ 5-6; TT, Vol. 4 at 622, 632-637, 676, Vol. 8 at 1539.)

4. Nordberg is the owner, by assignment, of United States Patent No. 4,478,373, entitled "Conical Crusher", issued on October 23, 1984 ("the 373 Patent"). (NFOF at ¶ 4; TFOF at ¶ 3.) Nordberg also owns Reexamination Certificate B1 4,478,373, which issued on January 30, 1990 and involved a reexamination of the original 373 Patent. (NFOF at ¶ 4; TFOF at ¶ 3.)

5. Nordberg contends that certain conical crushers manufactured or developed by Telsmith infringe (or contributorily infringe) upon claims 8-11 and 13 of the 373 Patent. These crushers include Telsmith's 1100F, the "10" series, and models 52, 57 and 84. (TFOF at ¶ 4.)

II. HISTORY AND GENERAL OPERATION OF CONICAL CRUSHERS

6. Conical crushers have existed since the early 1900's. (TFOF at ¶ 5.) They are primarily used in the mining industry to extract minerals from rock and in the aggregate industry to crush rock into various sizes for construction purposes. (TT, Vol. 1 at 14.) This suit involves crushers used for the latter purpose.

7. Conical crushers generally comprise a cylindrical and stationary lower frame assembly which encloses a gyrating conical head (138).² (NFOF at ¶ 7; TFOF at ¶ 5; TT, Vol. 1 at 15-16.) Above the lower frame assembly is an upper frame assembly which can move vertically relative to the lower frame. (NFOF at ¶ 7; TFOF at ¶ 5; TT, Vol. 1 at 15-19.) The upper frame includes a concave bowl (126) surrounding the conical head and a hopper (116) with a central opening to allow the entry of rock. (NFOF at ¶ 7; TFOF at ¶ 5; TT, Vol. 1 at 16.) The rock drops through the hopper into the space between the bowl and the conical head, which is called the crushing cavity. (Id.) Crushing results from the gyratory motion of the head. (NFOF at ¶ 7; TFOF at ¶ 5; TT, Vol. 1 at 16-17.) That is, the access of the head is mounted at a slight angle to the access of the machine. (NFOF at ¶ 7; TT, Vol. 1 at 16.) Because of this slanted access, the crushing cavity, as the head rotates, is narrow at one point on the circumference of the bowl and wider at another point. (NFOF at ¶ 7; TT, Vol. 1 at 16-17.) These two points can be referred to as the "closed" and "open" points of the crushing gap, respectively. (Id.) As the head rotates, the closed and open points similarly rotate around the crushing cavity. (Id.) Rock dropping into the crushing cavity is squeezed between the rotating head and the bowl at various points along the circumference of the bowl. (Id.) The squeezing action crushes the rock into a smaller size generally consistent with the size of the gap in the crushing cavity at the point at which the rock is struck. (TT, Vol. 1 at 16-17, 22-23.) This all happens very quickly. In a typical crusher, the head will complete 4-6 full rotations a second. (NFOF at ¶ 7; TT, Vol. 1 at 17.) The falling rock is typically struck 3-4 times before passing through the crushing cavity. (TT, Vol. 1 at 17.)

8. In order to crush rock, the movable upper frame containing the concave bowl must be held or "biased" against the lower frame. (NFOF at ¶ 8; TFOF at ¶ 5.) Tremendous forces are required to hold the frames together against the resistance forces exerted by the rock. (NFOF at ¶ 8; TT, Vol. 1 at 21.) The hold down force ranges from approximately 300,000 pounds of spring force for a small crusher to 1.2 million pounds for a large crusher. (Id.)

9. Although the upper frame is held against the lower frame during normal crushing, conical crushers typically have provisions allowing the upper frame to raise relative to the lower frame during three basic functions: adjustment, tramp relief and clearing. (NFOF at ¶ 9; TT, Vol. 1 at 22-24.)

10. Adjustment relates to setting the vertical distance between the head and the bowl at the relatively closed gap on the gyrational cycle of the head. (NFOF at ¶ 9; TT, Vol. 1 at 22-23.) That distance determines the size of the crushed rock product. (Id.) In order to control and/or vary the size of the product, conical crushers must have some way of adjusting the distance between the head and the bowl. (Id.) Even if a consistently-sized product is desired, the head must continually be lowered to accommodate for normal wear of the crushing elements. (Id.)

11. Tramp relief relates to the passing of uncrushable material. During the mining or quarrying of rock, large pieces of uncrushable material, such as steel or metal tools, often become inadvertently mixed in with the rock to be crushed. (NFOF at ¶ 10; TFOF at ¶ 6; TT, Vol. 1 at 24-25.) This material is called tramp. (Id.) If a piece of tramp enters a rock crusher and is larger than the setting of the relatively closed gap between the head and bowl, it will become caught in the crushing cavity. (Id.) The crusher will continually try to crush the tramp, which it cannot do. (Id.) If the upper frame was rigidly held against the lower frame at this point, extreme overstresses would develop and damage the crusher. (Id.) Thus, all conical crushers provide means for the upper frame to yield and raise under the pressures exerted by uncrushable tramp. (Id.) That "means", whatever form it may take, is generally referred to as "tramp relief" or "tramp release".

12. Clearing relates to removing jammed material from a stalled or shut down crusher. Occasionally, a crusher will stall or experience a power failure during crushing. (NFOF at ¶ 11; TT, Vol. 1 at 27-28.) In such cases, the crusher shuts down with a full load of rock in the crushing cavity. (Id.) Some of this rock becomes jammed or "pinched" in the cavity. (Id.) The crusher will not restart in that condition because the electric motor which powers the crusher is not strong enough to overcome the forces exerted by the jammed rock in the crushing cavity. (Id.) The rock must first be cleared from the crushing cavity. (Id.) Depending on the type of crusher involved, clearing is either done manually, with picks and crowbars, or mechanically, through some means of raising the upper frame so that the jammed rock may fall through. (Id.)

13. Another important feature in many conical crushers is an "abutting relationship" between the upper and lower frames during normal operation, created by the abutment of complementary beveled U-shaped surfaces on each frame. (NFOF at ¶ 20; TFOF at ¶ 12.) The abutment provides a positive, mechanical reference point for the crusher setting and for the return of the upper frame to a fixed operating position upon the passage of tramp material or the clearing of the crusher. (Id.) The abutting relationship has been well known in the crusher art for decades. (Id.)

14. Until the early-to-mid 70's, the most prevalent and traditional means for biasing the upper frame against the lower frame and for tramp release was the use of coiled springs. (NFOF at ¶ 12; TFOF at ¶ 7.) In spring crushers, the springs are mounted and precompressed between the frames so that the upper frame is biased toward the lower frame during normal crushing. (Id.) When tramp material enters the crushing cavity, it raises the upper frame relative to the lower frame, further compressing the springs. (Id.) The upward travel of the upper frame temporarily creates a larger crushing cavity, allowing the tramp material to pass without damaging the crusher. (Id.) Once the tramp passes, the springs expand and thereby lower the upper frame into its original position. (Id.)

15. The major disadvantage with spring crushers is that springs cannot be used to clear a stalled crusher. (NFOF at ¶ 14; TFOF at ¶ 7.) A stalled spring crusher must be cleared manually with picks and crowbars, which is a process that can take hours to complete. (Id.; TT, Vol. 1 at...