Hammer dirll

Patent metadata

Field	Value
Publication number	US-2017246734-A1
Application number	US-201715593434-A
Country	US
Kind code	A1
Filing date	May 12, 2017
Priority date	Sep 21, 2012
Publication date	Aug 31, 2017
Grant date	—

Abstract

A hammer drill having a motor mounted within a body and an output spindle; a tool holder mounted on the body capable of holding a cutting tool; a hammer mechanism having a piston; a reciprocating drive for converting rotary movement of the motor into reciprocating movement of the piston; a ram reciprocatingly driven by the piston via an air spring to strike a cutting tool held in the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use; an air replenishment mechanism capable of refreshing the air spring during certain time periods during normal use; the air replenishment mechanism capable of being adjusted to refresh the air spring during time periods within the hammer cycle and/or the system allows different volumes of air into or out of the air spring during the refreshment time periods.

First claim

1 . A method of altering the performance characteristics of a hammer comprising:
a body; a cylinder mounted within the body; a motor mounted within the body having an output spindle; a tool holder mounted on the body, the tool holder being capable of holding a cutting tool; and a hammer mechanism comprising:
a piston slideably mounted within the cylinder;
a reciprocating drive mechanism mounted within the body which, when the motor is activated, converts the rotary movement of the spindle of the motor into a reciprocating movement of the piston within the body;
a ram slideably mounted within the cylinder forward of the piston, the ram being reciprocatingly driven by the reciprocating movement of the piston via an air spring to repetitively strike a cutting tool when held by the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use; and
an air replenishment mechanism which is capable of refreshing the air spring during certain time periods within the hammer cycle during normal use;
wherein the method comprises the steps of adjusting the air replenishment mechanism so that it refreshes the air spring during different time periods within the hammer cycle and/or allows different volumes of air into or out of the air spring during the refreshment time periods to provide the most ideal performance characteristic for the hardness of material intended to be cut by the hammer.

2 . A method as claimed in claim 2 , wherein the cutting tool is capable of being held by the tool holder in a range of axial positions, the average axial position of the cutting tool within the tool holder during use being dependant on the hardness of the material being cut by the cutting tool, the method further comprising the steps of measuring the position of the cutting tool within the tool holder and selectively of adjusting the air replenishment mechanism dependent on the average position of the cutting tool within the tool holder.

3 . A method as claimed in claim 2 , wherein there is further provided:
a beat support structure mounted within the housing; a beat piece slideably mounted within the beat piece support structure, wherein the ram strikes the cutting tool via the beat piece, the method further comprising the steps of determining the position of a cutting tool within the tool holder by determining the position of the beat piece within the beat piece support structure.

4 . A method as claimed in claim 3 , the method further including the step of measuring the average position of the cutting tool within the tool holder or the step of measuring the average position of the beat piece within the beat piece support structure.

5 . A method as claimed in claim 1 , wherein the air replacement mechanism comprises a bleed hole formed through the wall of the cylinder and a valve connected to the bleed hole which, during the hammer cycle, selectively opens and closes the air bleed hole to allow air to pass through it during certain time periods within the hammer cycle and/or controls the volume of air passing through the bleed hole when it is open.

Assignees

• Black & Decker Inc

Inventors

• Gensmann Stefan D

Classifications

• B25D11/005 Primary

  Arrangements for adjusting the stroke of the impulse member or for stopping the impact action when the tool is lifted from the working surface · CPC title

• B25D2250/195

  Regulation means · CPC title

• B25D9/16

  Valve arrangements therefor {(B25D9/145 takes precedence)} · CPC title

• B25D2250/231

  Sleeve details · CPC title

• B25D2250/221

  Sensors · CPC title