Handle

Abstract

A safety razor handle is provided for use with a blade unit which is releasably mountable on the handle, and which includes a recess partially defined by spaced apart parallel vertical planar surfaces and a latch structure. The handle includes a head portion having fixed surfaces of size and shape conforming to the recess of the blade unit for being received therein to position the blade unit on the handle for use in a shaving operation. It also includes a latch member movable between first and second positions. In the first position, the latch member is disposed to latch the latch structure of the blade unit when the surfaces of the head portion are received in the blade unit's recess. The handle further includes biasing means disposed to exert a force on the latch member toward the first position when the latch member is removed from that position and a release member movable between first and second positions and engageable with the latch member. Movement of the release member from the first position to the second position causes motion of the latch member from its first position to its second position and consequent unlatching of the blade unit latch structure. Preferably, the latch member comprises a portion of a spring.

Description

This invention relates to safety razors and, more particularly, to improved means for retaining a blade unit upon a safety razor handle.

It is a principal object of the present invention to provide a safety razor handle which includes improved structure for releasably retaining a blade unit thereto. Further objects include the provision of such a handle which will so releasably retain a shaving head that has cutting edges facing in two opposed directions and the provision of retention means which will substantially eliminate undesirable "wobble" of the blade unit during a shaving operation. It is an additional object of the invention to provide such a safety razor handle which, while firmly retaining a blade unit thereto, provides for the convenient and rapid release of the blade unit when so desired.

In accordance with the invention a safety razor handle is provided for use with a blade unit which is releasably mountable on the handle and which includes a recess partially defined by spaced apart parallel vertical planar surfaces and a latch structure. The handle includes a head portion having fixed surfaces of size and shape conforming to the recess of the blade unit for being received therein to position the blade unit on the handle for use in a shaving operation. It also includes a latch member movable between first and second positions. In the first position, the latch member is disposed to latch the latch structure of the blade unit when the surfaces of the head portion are received in the blade unit's recess. The handle further includes biasing means disposed to exert a force on the latch member toward the first position when the latch member is removed from that position and a release member movable between first and second positions and engageable with the latch member. Movement of the release member from the first position to the second position causes motion of the latch member from its first position to its second position and consequent unlatching of the blade unit latch structure. Preferably, the latch member comprises a portion of a spring.

In one particular preferred embodiment of such a safety razor handle there are a pair of such latch members each comprising a portion of the same wire spring. A pair of release members are provided which are rotatable about an axis for engagement of the latch members. Rotation of the release members is accomplished by the razor's user by exertion of force against a portion of each release member which protrudes from the handle body. This rotation causes the movement of the latch members and consequent unlatching of the blade unit.

In a second particular preferred embodiment a pair of latch members comprise portions of separate springs. The release member is supported for movement along the handle's axis and includes a pair of surfaces disposed to engage the latch members, for unlatching the blade unit, upon movement of the release member.

Other objects, features, and advantages of the invention will appear from the following description of particular preferred embodiments taken together with the accompanying drawings. In the drawings:

FIG. 1 is a perspective view of a razor handle constructed according to the invention and a blade unit suitable for use with that handle;

FIG. 2 is a partially broken-away, exploded view of the handle of FIG. 1;

FIG. 3 is a partially broken-away top plan view of the handle of FIG. 1;

FIG. 4 is a partially broken away front elevation of the upper portion of the handle of FIG. 1;

FIG. 5 is a sectional side view of the upper portion of the handle of FIG. 1 and the blade unit of FIG. 1, the blade unit being retained on the handle in position for a shaving operation;

FIG. 6 is a view similar to FIG. 5 with the blade unit being removed from the handle;

FIG. 7 is a bottom plan view of the blade unit of FIG. 1;

FIG. 8 is a view taken at 8--8 of FIG. 7;

FIG. 9 is a perspective view of an alternative embodiment of a razor handle constructed according to the invention and a blade unit suitable for use therewith;

FIG. 10 is a side elevation of the handle and blade unit of FIG. 9;

FIG. 11 is a view taken at 11--11 of FIG. 10;

FIG. 12 is a view similar to FIG. 11 with the blade unit being removed from the handle;

FIG. 13 is an exploded perspective view of the upper portion of the handle of FIG. 9 and of the blade unit of FIG. 9;

FIG. 14 is a bottom plan view of the blade unit of FIG. 9;

FIG. 15 is a view taken at 15--15 of FIG. 14; and

FIG. 16 is a view taken at 16--16 of FIG. 14.

One preferred embodiment may be described with reference to FIGS. 1-8. Referring in particular to FIG. 1, there is shown a safety razor comprising a handle 10 and a blade unit 12 releasably mountable upon the handle. The handle includes integral elongated grip portion 14 and head portion 15, the latter suitable for receiving the blade unit 12. The handle is 4.295 inches high and the head portion 15 defines an upper rectangular surface which is 1.560 inch long and 0.420 inch wide, having a central rectangular opening 108 for receiving latch members 26 of the blade unit 12. Spring 84 is disposed in the head portion 15 to engage the blade unit latch members 26 when the blade unit is mounted on the handle.

The blade unit 12, which has an overall length of 1.560 inch and an overall width of 0.800 inch, comprises a pair of plastic cap and base members 20, 22 which are permanently secured to each other and which have blade means 166 clamped between them. The member 22 includes a downward-facing recess 24, of generally rectangular cross section, which is suitable for receiving the upper portion of handle 10 (as described in detail below). Recess 24 is 0.440 inch wide, suitable for receiving the head portion of handle 10. The latch members 26 project downwardly from the bottom of base member 22.

The details of construction of the handle 10 will be described with reference to FIGS. 1-6.

The handle consists of a plastic body 16, a pair of identical metallic side plates 60, latch spring 84, and a pair of identical release members in the form of plastic levers 92 suitable for applying pressure against portions of the latch spring 84 as described in detail below.

The plastic body 16 includes a central web 28 which is integral with symmetrically disposed end panels 30. Panel 30 have a multiplicity of ridges 18 on their outer surfaces in the grip portion 14. The longitudinal axis of the handle 10, and in particular of the grip portion 14, is coincident with the center of web 28. Reinforcing ribs 32 are provided on opposite sides of web 28 and are integral with web 28 and panels 30. A pair of downwardly opening notches 31 are provided in the thickened lower end 33 of web 28.

Panels 30 merge in a smooth curve with flanges 34 of head portion 15. The flanges 34 are generally planar and the plane in which they lie is generally perpendicular to the axis of the grip portion 14 of the handle. Each flange 34 is integral with a raised platform 36. The upper surface of platform 36 includes a raised portion 38 and a depression 40. The platform 36 is also integral with downwardly extending reinforcing leg 42, itself integral with the upper most reinforcing rib 32a and an end panel 30. Rod 44 extends between legs 42 intermediate platforms 36 and rib 32a. The legs 42 present surfaces 46 which face each other and have a separation of 0.100 inch. Offset parallel end surfaces 48 of platform 36 have a separation of 0.220 inch. Lips 50 at the outer ends of flanges 34 extend upwardly providing upper surfaces 52 and side surfaces 54. The metal side plates 60 each include an elongated planar panel 62 having a pair of inwardly directed flanges 64 which extend the length of panel 62, the width of flanges 64 increasing uniformly from bottom to top. Foot 66 and upward projection 68 are integral with panel 62.

Flanges 64 merge at their upper, wider ends with flanges 70 which protrude from the lower edges of widened head portion 72 of side plate 60. The head portion 72 includes an integral upper plate 74 projecting from right angle bend 73. The plane of plate 74 is thus perpendicular to that of vertical surface 71 adjacent bend 73. The plate 74 includes a central notch 76, 0.210 inch wide and 0.155 inch deep. Tabs 78 are bent downwardly from the inner edge 80 of plate 74. Each tab 78 is 0.200 inch wide and extends downwardly from the upper surface of plate 74 for a distance of 0.090 inch.

Opening 82 is provided in each panel 62 which is 0.100 inch wide and 0.351 inch high with its lower edge being 0.693 inch below the upper surface of plate 74.

The panel 62 is 0.357 inch wide at its lower end where it is integral with foot 66 and each lateral edge of the panel 62 tapers inwardly at 0.degree.43'. Each flange 64 is approximately 0.105 inch wide at its upper portion where it is integral with flange 70 and tapers at 1.degree.04' to a zero width adjacent foot 66.

Spring 84 is formed in a generally "dumbell" shape from 0.025 inch diameter stainless steel, spring tempered wire. The central, narrower formed portion includes parallel lengths 86 of wire which are separated by 0.155 inch. The total width at each of the wider formed ends 88 is 0.350 inch and the total length of the spring is 1.440 inch. At one of the ends 88 the two ends 90 of the wire from which the spring 84 is formed are bent back toward the center of the spring.

Levers 92 are molded from a resilient plastic and are mounted for rotational movement about rod 44. Each lever includes a surface 94 for engagement of a length 86 of spring 84 and has an arcuate recess 96, having a radius of curvature of 0.050 inch, which engages the rod 44. Surface 98 above recess 96 and surface 100 below recess 96 (seen best in FIGS. 5 and 6) are inclined to each other at an angle of 15.degree.. Surface 102, on the opposite side of the main body 104 of the lever 92 is parallel to surface 100. Cantilevered finger 106 projects at an angle of 30.degree. from the lower portion of surface 94 for a distance of approximately 0.200 inch. The finger 106 is approximately 0.015 inch thick and 0.040 inch wide. As best seen in FIGS. 1, 5 and 6, in the assembled handle 10 the body 104 of lever 92 partially projects through opening 82 in side plate 60 with exposed surface 102 making an angle of approximately 30.degree. with the axis of the handle 10.

In the assembled handle 10, spring 84 lies on platforms 36 with raised platform portions 38 disposed between parallel lengths 86 of the spring 84. Levers 92 have surfaces 94 in contact with lengths 86 of spring 84, recesses 96 engaged with rod 44, and surfaces 102 protruding through openings 82 in side plates 60. Each side plate 60 has its projection 68 inserted into a notch 31 and flanges 64 disposed between panels 30 to abut reinforcing ribs 32. In the head portion flanges 70 of the side plates overlie flanges 34 of the plastic body, while plate 74 overlies platforms 36. Tabs 78 are disposed within recesses 40 of platforms 36. Recesses 76 on the upper plates 74 of side plates 60 cooperate to provide a rectangular opening 108 in the upper surface of handle head portion 15, which surface is defined by plates 72 and edges 52 of lips 50 of a plastic body 16. Central, latching portions 110 of parallel lengths 86 of spring 84 are exposed in opening 108 as are the upper portions of levers 92.

The blade unit 12 may be described with reference to FIGS. 1 and 5-8. A frame comprises plastic cap and base members 20, 22 which are secured together, with blade means 116 disposed therebetween, by means of pins 124 of member 20 which pass through cooperating openings 126 in member 22. Pins 124 have deformed heads 128 which bear upon bosses 130 of member 22 to secure the components of blade unit 12 together as a single unit. The member 22 includes a platform comprising integral planar portions 132, 134 the upper, blade-supporting surfaces of which intersect in an angle of 140.degree.. (The axis of handle 10 bisects this angle so that each blade lies in a plane inclined at 70.degree. to the handle's axis.) Outer blade supports 136 are connected to the platform by webs 138 defining debris removal apertures 139. Guard structures 140 are spaced apart from supports 136 and are connected thereto by webs 142. Apertures 144 are thus provided between the guard structures 140 and the supports 136.

The base member 22 has a set of five ribs 146 extending transversely across the lower surfaces of portions 132, 134 and integral therewith. Ribs 146 provide downwardly facing, horizontal surfaces 148 and, where the ribs 146 are integral with webs 138, vertical surfaces 150. Surfaces 148 and 150 cooperate to define the recess 24 mentioned above. As best seen in FIG. 7 a symmetrically located pair of ribs 146a includes tiny crushbump locators 151 protruding from its vertical surfaces 150a. Latch members 26, integral with portions 132, 134, include an upper stem 154 and a wider foot portion 156 which serves as a latching structure and has shoulders 158 adjacent the stem 154. Camming surfaces 160 are provided on portions 156 below shoulders 158. (Rectangular openings 162, 164 in portions 132 and 134 simplify molding of plastic member 22.)

Cap member 20 includes an opening 161 in each end wall 163 (best seen in FIG. 1). A pair of projections 165 protruding from the central undersurface of member 20 are seated in appropriately positioned recesses 167 (best seen in the embodiment of FIG. 15) on member 22.

The blade means, indicated generally at 166, comprises two sets, each set including a pair of blades 168, 170 having cutting edges 172, 174 respectively, and a spacer 176 between the blades. Edges 172 overlie slots 144 and edges 174 are spaced further inwardly of the blade unit 12 from edges 172. Blades 168, 170 and spacers 176 include appropriate openings for receiving projections 124. Additionally, lower blades 168 include openings aligned with apertures 139 of member 22 (see FIG. 7), thereby permitting shaving debris which is deposited between blades 168 and 170 to flow through apertures 139 and away from cutting edges 172, 174.

In the embodiment described above, the blade unit 12 is releasably mountable on the handle 10 as follows. The blade unit 12 is moved toward the handle 10 oriented such that the planes of the stems 154 of latch members 26 are parallel to the axis of the handle 10 with the latch members 26 directly above opening 108 in the upper surface of the handle head portion 15. As the blade unit and handle are brought together, the camming surfaces 160 on latch members 26 force the center, latch sections 110 of spring lengths 86 away from each other to permit the passage of wider, lower portions 156 of latch structures 26 past the spring. As this is accomplished, the respective spring latch portions 110 snap back to their original configuration and latch the shaving head 12 to the handle by bearing upon shoulders 158, as best seen in FIG. 5.

In addition to the latching action between the handle and blade unit, the recess 24 in the underside of blade unit 12 serves as a socket to receive the appropriately shaped and sized head portion 15 of handle 10. Specifically, the horizontal surfaces 148 of ribs 146 engage the upwardly facing flat portions 74 of side plates 60 and edges 52 of lips 50. The flat vertical side surfaces 71 of side plates 60 adjacent the right angle bend 73 engage the vertical surfaces 150 at the sides of recess 24. The crush-bump locators 151 deform to accommodate the exact size of the particular handle head portion and thereby assure a snug fit.

The snug fit of the head portion of the handle into the recess formed in the lower portion of the blade unit is effective to prevent slight relative movement of the blade unit with respect to the handle during a shaving operation, while the latching engagement of the latch members (i.e., spring portions 110) of the handle with the latch structures 26 of the blade unit serves to retain the blade unit upon the handle.

With the blade unit 12 thus mounted on the handle 10 the razor is ready for use in a shaving operation. Removal of the blade unit 12, for replacement or other reasons, is accomplished by exerting compressive force against the oppositely disposed surfaces 102 of the movable levers 92 thus causing rotation, in opposite senses, of the levers 92 about the rod 44. Surfaces 94 bear upon latch sections 110 of the spring 84 and force those sections outwardly against the force of the spring as a whole, the levers 92 thus serving as release members. This motion of the spring latch sections 110 removes them from engagement with shoulders 154 on blade unit latch members 26 and thus unlatches the blade unit 12 thereby permitting its removal (see FIG. 6).

As best seen in a comparison of FIGS. 5 and 6, this rotation of levers 92 also causes a deformation of the levers 92 in that the projection 106 is bent toward the main body of the respective lever 92. Since the lever 92 is formed from a resilient plastic material, this deformation produces a biasing force, in addition to the force exerted by spring 84, tending to return the levers 92 to the orientation shown in FIG. 5 once the external force exerted by the razor's user is withdrawn.

(Openings 161 in end walls 163 of member 20 provide for a thin central portion of end walls 163 which serve to permit flexure of member 20, as may occur, for example, during assembly of the blade unit.)

Another embodiment of the invention is illustrated by FIGS. 9-16. The blade unit 12a is identical to the blade unit 12 of FIGS. 1 and 5-8 but for the 90.degree. rotation of latch members 26a and openings 162a, 164a (best seen in FIG. 14).

The handle 200 includes an elongated grip portion 202 of generally circular cross section and tapering diameter and a head portion 203. The handle 200 is substantially the same height as the handle described above and the upward facing surfaces (discussed further below) of the head portion 203 again define a rectangle 1.560 inch long and 0.420 inch wide.

The handle grip portion 202 comprises a metallic body 204 and a pair of plastic inserts 206, each having a multiplicity of ridges 208. The head portion 203 is mounted upon a reduced diameter portion 210 of metallic body 204 and comprises a base 212, a pair of springs 214, and a cap 215. Base 212 includes a pair of side edges each having a depressed central portion 218 which support springs 214. End walls 220 of base 212 provide side edbes 222 and upper edges 224. The cap 216 includes edges plate 226 and vertically disposed side flanges 228 integral therewith. Plate 226 has a central opening 230 and depressed tongues 232 on either side of opening 230 spaced apart therefrom. Downward projecting tabs 234 are integral with plate 226 adjacent the side edges of opening 230. Raised end portions 236 of the side edges of base 212 join the depressed central portions 218 to provide stop surfaces 238. The upper surface of plate 226 and edges 224 of end walls 220 define the rectangular structure, mentioned above, which can be received in the recess 24 (see FIG. 15) on the associated blade unit.

Springs 214 are accordian-like, formed wire compression springs having five parallel formed legs each, with neighboring legs connected by rounded 180.degree. bends. The innermost legs 214a serve, in a manner to be described, as latch members for engagement with latch structures 26a on blade unit 12a.

In the assembled handle, base 212 is mounted upon portion 210 of body 202 and springs 214 are supported on edge portions 218 with their outermost legs abutting stop surfaces 238. The innermost legs 214a of springs 214 underlie opening 230 of cap 216 and abut the side edges of tabs 234. The cap 216 is placed over the base 212 with flanges 228 lying outside of side edges 236, 218. Ends 220 of base 212 are crimped inwardly to retain cap 216 in place. Tongues 232 cooperate with stop surfaces 238 to provide a firm structure against which the outermost lengths of springs 214 bear.

Movable release member 240 is disposed within body 204 and includes a head 242 having inclined surfaces 244 which engage the innermost lengths 214a of springs 214. The opposite end 246 of member 240 is provided with teeth 248 which engage mating structure 249 on the internal surface of actuator 250. Actuator 250 includes a portion 252 which extends beyond the outer end of body 204 and flange 254 immediately thereabove. Coil spring 256 is disposed around actuator 250 between flange 254 and stationary ring 258.

In the assembled handle, spring 256 biases actuator 250, and thus movable member 240, downwardly for a maximum exposure of portion 252 and maximum withdrawal of head portion 242 of member 240 below springs 214. The user may apply pressure to portion 252 to overcome the biasing force of spring 256 and move plunger 240 in the direction of cap 216 of the handle 200. As this is done the tapered surfaces 244 cam outwardly (i.e., toward the respective ends 220 of base 212) the innermost lengths 214a of springs 214 (compare FIGS. 11 and 12).

The attachment and release of a blade unit 12a to the handle 200 is as follows. The blade unit 12a is brought together with the cap 216 with latch members 26a aligned with opening 230. The head portion 242 of plunger 240 is located centrally within the opening 230 and is sized to fit between the two members 26a as they are inserted through the opening 230. As the blade unit 12a and handle are brought together, surfaces 160a of members 26a cam lengths 214a of springs 214 outwardly. After the surfaces 160a have passed below the level of lengths 214a, the latter spring back into their original positions and latch the members 26a by bearing upon shoulders 158 adjacent stem portion 154, as best seen in FIG. 11. Concurrently, edges 224 and 222 of end portions 220 of base 212 engage surfaces 148a and 150 of outermost ribs 146 and plate 226 engages surfaces 148 and 150 of interior ribs 146 (see FIG. 11).

Release of the blade unit 12 is accomplished by the user by applying pressure to portion 252 of actuator 250, as described above, This pressure forces plunger 240 upward thereby causing surfaces 244 to cam length 214a of springs 214 outwardly, thus releasing the latching action upon shoulders 158 and permitting removal of the blade unit 12a, as shown in FIG. 12.

While particular presently preferred embodiments of the invention have been described in detail, it will be apparent that other embodiments are within the scope of the invention and the appended claims.

Claims

What is claimed is:

1. A safety razor handle adapted for use with a blade unit which is releasably mountable thereupon and has a recess and latch means,

said handle including a grip portion,

a transversely extending head portion at the end of said grip portion, said head portion having a flat upper surface bounded by a peripheral surface of size and shape conforming to said recess for being received therein to position said blade unit on said handle for use in a shaving operation;

latch structure disposed within said head structure, said latch structure comprising a portion of a spring disposed for movement in a plane parallel to said upper surface and being movable between first and second positions, said latch structure in said first position being disposed to latchingly engage said blade unit latch means when said surfaces of said head portion are received in said blade unit recess;

an aperture in said upper surface of said head portion through which said blade unit latch means may be inserted for engagement with said latch structure;

biasing means disposed to exert a force on said latch structure toward said first position when said latch structure is moved from said first position; and

release structure movable between first and second positions and engageable with said latch structure, movement of said release structure from said first position to said second position causing motion of said latch structure from its first position to its second position and consequent unlatching of said blade unit latch means.

2. A safety razor handle as claimed in claim 1 wherein said release structure includes a surface engaged with said spring portion.

3. A safety razor handle as claimed in claim 1 wherein said latch structure comprises a pair of spaced spring portions.

4. A safety razor handle as claimed in claim 3 wherein said pair of spring portions are portions of a single wire spring.

5. A safety razor handle adapted for use with a blade unit which is releasably mountable thereupon and has a recess and latch means,

said handle including a head portion of size and shape conforming to said recess for being received therein to position said blade unit on said handle for use in a shaving operation;

a single wire spring, said spring having a pair of spaced spring portions that define latch structure,

said latch structure being movable between first and second positions, said latch structure in said first position being disposed to latchingly engage said blade unit latch means when said surfaces of said head portion are received in said blade unit recess;

said single wire spring including biasing portions disposed to exert a force on said latch structure toward said first position when said latch structure is moved from said first position; and

release structure movable between first and second positions and engageable with said latch structure, said release structure including a pair of release members, each said release member having a surface engaged with one of said spring portions, movement of said release structure from said first position to said second position causing motion of said latch structure from its first position to its second position and consequent unlatching of said blade unit latch means.

6. A safety razor handle as claimed in claim 5 wherein each said release member is rotatable about an axis.

7. A safety razor handle as claimed in claim 6 wherein said handle has a longitudinal axis and said axis about which said release members are rotatable is perpendicular to said longitudinal handle axis.

8. A safety razor handle as claimed in claim 7 and further including means for biasing each said release member toward a rotational orientation in which each said spring portion is disposed to engage said latch structure of said blade unit when said handle head portion is received in said recess.

9. A safety razor handle as claimed in claim 7 wherein each said release member includes a thin, cantilevered finger of resilient material, said finger engageable with a surface of the razor handle, whereby each said release member is rotationally biasable.

10. A safety razor handle adapted for use with a blade unit which is releasably mountable thereupon and has a recess and latch means,

said handle including a head portion of size and shape conforming to said recess for being received therein to position said blade unit on said handle for use in a shaving operation;

latch structure comprising a pair of spaced spring portions,

said latch structure being movable between first and second positions, said latch structure in said first position being disposed to latchingly engage said blade unit latch means when said surfaces of said head portion are received in said blade unit recess;

release structure movable between first and second positions and engageable with said latch structure, said release structure including a common release member and each of said spring portions engaging a surface of said release member, movement of said release structure from said first position to said second position causing motion of said latch structure from its first position to it second position and consequent unlatching of said blade unit latch means.

11. A safety razor handle as claimed in claim 10 wherein said handle has a longitudinal axis and said release member is disposed for motion along said longitudinal axis.

12. A safety razor handle as claimed in claim 11 and further including means for biasing said release member in a direction along said longitudinal axis away from said spring portions.

13. A safety razor handle as claimed in claim 10 wherein each said spring portion is a portion of a spring wire.

14. A safety razor handle adapted for use with a blade unit which is releasably mountable thereupon and has a recess and latch means,

said handle including a head portion of size and shape conforming to said recess for being received therein to position said blade unit on said handle for use in a shaving operation, said head portion including an upper surface having an aperture therein;

latch structure including an elongated spring member housed in said head portion and disposed on one side of said aperture for latching engagement with the latch means of a cooperating blade unit, said latch structure being movable between first and second positions, said latch structure in said first position being disposed to latchingly engage said blade unit latch means when said surfaces of said head portion are received in said blade unit recess;

biasing means disposed to exert a force on said latch structure toward said first position when said latch structure is moved from said first position; and

release structure movable between first and second positions and engageable with said latch structure, movement of said release structure from said first position to said second position causing motion of said latch structure from its first position to its second position and consequent unlatching of said blade unit latch means.

15. The safety razor handle as claimed in claim 1 wherein said latch structure includes two opposed elongated wire spring portions housed in said head portion and disposed on opposite sides of said aperture for latching engagement with the latch means of a cooperating blade unit.