ABRADING APPARATUS

• US 3,866,357 A
• Filed: 06/06/1974
• Issued: 02/18/1975
• Est. Priority Date: 06/06/1974
• Status: Expired due to Term

• Current Assignee: John William Callahan, Martin John Capdevielle
• Original Assignee: John William Callahan, Martin John Capdevielle
• Inventors: Callahan, John William, Capdevielle, Martin John
• Primary Examiner(s): Kelly, Donald G.
• Application Number:
  US05/477,127
• Time in Patent Office: 257 Days
• Field of Search: 51/8R,12
• US Class Current: 451/2
• CPC Class Codes: B24C 3/00 Abrasive blasting machines or devices; Plants
• CPC Class Codes: B24C 7/0046 the abrasive material being fed in a gaseous carrier

Abstract

Abrading apparatus, including a conduit for conducting a mixture of pressurized gas and abrasive powder, is provided with a pressure-tight enclosure for containing leaks from the conduit, also a pressure-responsive switch for detecting leaks into the enclosure and for closing the valve which controls the flow of compressed gas from its source. The same pressure-responsive switch preferably de-energizes a vibrator in the abrasive mixture supply system; and it simultaneously lights a warning lamp and depressurizes the compressed gas supply line.

Claims

1. In abrading apparatus having a nozzle, delivery means providing a pressurized mixture of compressed gas and abrasive powder, and a conduit for conducting said pressurized mixture from said delivery means to said Nozzle, wherein said delivery means includes a solenoid valve which when energized activates said delivery means and which when de-energized deactivates said delivery means, that improvement comprising:

a. a pressure-tight enclosure enclosing said conduit in at least partly spaced relationship to define a chamber therebetween;

b. a pressure-responsive switch including 1. a bellows connected to said enclosure in communication with said chamber whereby said bellows is extendable in response to a substantial increase of pressure in said chamber, 2. a switch connected in an electrical circuit with said solenoid valve to energize said solenoid valve in a first position of said switch, said switch being operably associated with said bellows for movement thereby to a second position wherein said solenoid valve is de-energized when said bellows is extended, 3. retaining means holding said switch in second position against return to the first position when said bellows is depressurized, and 4. manual reset means operable for releasing said retaining means and returning said switch from second position to first position;

whereby a leak of said abrasive powder from said conduit is contained at least partly within said enclosure and said delivery means is deactivated when a leak occurs in said conduit.

2. Abrading apparatus according to claim 1 further including a relief valve having a solenoid connected between atmosphere and said delivery means, said relief valve being closed to atmosphere when its solenoid is de-energized and open to atmosphere when its solenoid is energized, said switch in first position effecting de-energization of said solenoid of said relief valve, and said switch in second position effecting energization of said solenoid valve of said relief valve, whereby said delivery means is depressurized when a leak occurs in said conduit and said bellows extends in response to a substantial increase in pressure in said chamber.

3. retaining means holding said switch in second position against return to the first position when said bellows is depressurized, and

4. Abrading apparatus according to claim 1 wherein said delivery means includes structure defining a mixing chamber for mixing compressed gas and abrasive powder into a pressurized mixture for abrading;

a source of compressed gas connected to said mixing chamber, and an electrically operated vibrator mounted to said structure, said vibrator being connected in said circuit to said switch for energization in first position of said switch and for de-energization in second position of said switch, whereby said vibrator is inoperative when a leak occurs in said conduit which extends said bellows by a substantial increase of pressure in said chamber.