TRIPLETT, Thomas L. (6041 Terrace Circle, Rockford, Minnesota, 55373, US)
SCHROEDER, James C. (9000 160th Lane, Ramsey, Minnesota, 55303, US)
TRIPLETT, Thomas L. (6041 Terrace Circle, Rockford, Minnesota, 55373, US)
| CLAIMS 1. A spring assembly for use in a screed box used in a thermoplastic line striper holding molten plastic material prior to dispensing, said spring assembly comprising: a cylindrical sleeve having first and second ends, said sleeve having a slot opening from said first end and an aperture adjacent said second end; and a spring having first and second ends and located in said sleeve. 2. The spring assembly of claim 1 further comprising a mounting tube located in said aperture and extending diametrically across said sleeve, said spring first end engaging said mounting tube. |
TECHNICAL FIELD
This application claims the benefit of US Application serial number 61/228,676, filed July 27, 2009, the contents of which are hereby incorporated by reference.
BACKGROUND ART
Devices for applying thermal markings and striping to roadways and the like are well known.
DISCLOSURE OF THE INVENTION
It is an object of this invention to improve spring life by integrating an enclosure that protects the spring from intense heat and thermoplastic spills. It is further an object to allow installation and removal without tools as well as being safer. Because a torch is used to heat dies up before use the spring takes much of the heat. Heat causes the springs to lose strength and eventually fail. A failed spring allows the die to leak. This is the primary failure mode for die springs.
Current/competitive springs require a pliers to install. The new design is protected from heat. Heat is the number one cause of spring failure. These and other objects and advantages of the invention will appear more fully from the following description made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 shows a screed box with the inventive spring design having the shield partially cut away.
Figure 2 shows the spring design of the instant invention with an integral shield. Figure 3 shows an external view of the shield.
Figure 4 shows another external view.
Figure 5 is a sectional view taken along line 5-5 of Figure 4.
Figure 6 is an external view of one side of the shield sleeve.
Figure 7 is an end view of the shield sleeve. Figure 8 is an external view of the other side of the shield sleeve.
Figure 9 is an external view of the mounting tube.
Figure 10 is an end view of the mounting tube.
Figure 11 is an end view of the spring. Figure 12 is a side view of the spring.
BEST MODE FOR CARRYING OUT THE INVENTION
A screed box 10 used in a thermoplastic line striper 12 holds molten plastic material prior to dispensing. A spring assembly 14 tensions the screed assembly and is subjected to substantial heat during operation. Spring assembly 14 is comprised of a sleeve 16 having a slot 18 therein. A hole 20 is drilled diametrically through sleeve 16 and has located therein a mounting tube 22. One end 24 of spring 26 is engaged by mounting tube 22 while the free end 28 of spring 26 can be seen in slot 18 in Figure 2. To install spring assembly 14, the free end 28 of spring 26 is looped over shaft 30 on door 34 by inserting shaft 30 through slot 18. The user then pulls on the outside of sleeve 16 and stretches spring 26 until the hole 20 and mounting tube 22 can be placed over shaft 32 on the main body of screed box 10.
It is contemplated that various changes and modifications may be made to the spring assembly without departing from the spirit and scope of the invention as defined by the following claims.