Disposable blade cartridge utility knife

1. In a knife, the combination, comprising

a) a cartridge,

b) a blade carried by a portion of the cartridge,

c) an endwise first direction projecting holder supporting the cartridge so that the blade projects endwise from the holder, the holder having a shoulder portion,

d) a shield for the blade, carried to be pivoted relative to the holder and blade to expose the blade, for cutting,

d) the cartridge including a stem projecting in a second endwise direction away from the blade, the holder defining an endwise third direction projecting guide slot receiving the stem, said first, second and third endwise directions projecting in the same relative direction, the blade at all times remaining outside the holder, there being a shield pivot carried by the stem, to enable said shield to pivot,

f) there being first side openings in the holder, and spring arms with catches thereon presented at opposite sides of the holder, via said side openings, to be manually pushed oppositely inwardly to allow slide out removal of the stem from the holder,

g) there being additional manually graspable side openings sunk in opposite sides of the holder and spaced apart in said first direction, away from said shield pivot, first side openings, and blade,

h) said catches carried by the stem to protrude outwardly within two of the first side openings sunk in opposite sides of the holder, the catches located in recessed positioning in said first side openings, and projecting in said stem second endwise direction, said catches being releasably attached to said shoulder portion,

i) said holder including a curved handle portion defining ribs presented at said additional opposite side openings and spaced from said catches in said endwise first direction, remotely from the blade, the ribs extending, generally transversely of handle portion length, said additional side openings successively decreasing in the transverse width dimension, directionally rearwardly away from the pivot, to provide curved handle taper, said ribs including a first rib, said first side openings being defined between said shoulder portion and said first rib,

j) the shield being removably and pivotally carried by the cartridge, and the cartridge defining a pivot to which the shield has connection,

k) the cartridge received by the holder via the stem and slot to be manually controllably endwise removable and replaceable, by simultaneously depressing said spring arms, the cartridge defining an elongated portion supported by an elongated handle portion of the holder,

l) said catches forming a detent connection that holds the cartridge elongated portion to said elongated handle portion,

m) said ribs progressively decreasing in transverse width, in a direction away from the catches,

n) there being guide means whereby the shield is rotatable forwardly and whereby the shield retracts bodily as it is rotated rearwardly toward an open position exposing the blade edge,

o) and including a return spring located to urge the shield toward a closed position,

p) the shield being rotatably supported by the cartridge, and wherein the shield comprises two sections that are held together at opposite sides of the blade and at opposite sides of said portion of the cartridge.

2. The combination of claim 1 wherein the blade and shield project endwise relative to said handle portion of the holder.