Abstract:
A light weight, low cost grinder assembly for a pepper grinder includes male and female rotary grinding members spaced to create between them a gap which determines the size of the ground pepper. Each of the male and female members is a composite of a polymer part and a corrugated steel grinding member which is advantageously produced by pressing.

Description:
TECHNICAL FIELD 
   The present invention relates to a condiment grinder, and particularly to the grinding apparatus of a condiment grinder. 
   BACKGROUND OF THE INVENTION 
   Various types of grinder are known for pepper and other condiments. In a grinding assembly of these devices, grinding is effected by relative rotation between an inner grinding element and an outer grinding element. The two elements have, on the respective contact surfaces, teeth or ribs to grind the condiment. The surfaces are spaced so as to create between them a gap which determines the final grain size of the ground material. One or both of the grinding elements may be tapered and the teeth or ribs may be helicoid to promote axial movement of the condiment between the grinding elements. 
   Conventionally, grinding elements are manufactured from cast stainless steel. This allows their complex shape to be readily produced in a hard material that provides long life and corrosion-free performance. In grinders for many applications however, not only disposable grinders, manufacturing costs are an important consideration. Producing cast grinding elements is relatively costly and cast grinding elements are also heavy. It will therefore be understood that there is a need for light weight grinding elements having like performance to the prior art grinding elements, but which can be made more cost effectively. 
   DISCLOSURE OF THE INVENTION 
   According to one aspect of the present invention there is provided condiment grinding apparatus comprising:
         a female grinding element,   a first aperture extending through the female grinding element, the first aperture defining an inner surface of the female grinding element,   wherein the female grinding element is corrugated to provide first corrugated surface portions in the inner surface of the female grinding element, and second corrugated surface portions on an outer surface of the female grinding element; and   a male grinding element,   a second aperture extending through the male grinding element,   wherein the male grinding element is corrugated to provide third corrugated surface portions in an outer surface of the male grinding element, and fourth corrugated surface portions on an inner surface of the male grinding element,   a polymeric core in the male grinding element in contact with the inner surface of the male grinding element   a third aperture extending through the core, the second and third apertures being aligned for receiving a grinding shaft, whereby   the inner surface of the female grinding element and the outer surface of the male grinding element form a cavity for grinding condiment between the first and third corrugated surface portions upon relative rotation between the shaft and the female grinding element.       

   Preferably the first, second and third apertures are coaxial, the second and third apertures having a substantially square shaped cross-section, and the male grinding element is tapered, having a narrow first end and broader axially opposing second end, wherein the male grinding element extends between a square edge of the second aperture at the first end and a corrugated annular edge at the second end. 
   Preferably outer faces of the first and second ends of the male grinding element are substantially parallel. 
   Preferably the male and the female grinding element are formed by pressing of sheet metal. 
   Preferably the female grinding element has a plurality of circumferentially spaced teeth projecting from the inner surface of the female grinding element, each tooth formed by punching, the sheet metal being sheared by the punching action to separate first and second edges, the first edge being displaced from the second edge to form an opening, the apparatus further including a sleeve extending externally about the female grinding element to close each said opening. 
   Preferably the first and second edges are elongated in the axial direction and lie substantially in a common radial plane, a tapered face of each tooth extends substantially circumferentially from the first edge to the inner surface. Preferably each tapered face extends in a common circumferential direction. 
   Preferably the sleeve and female grinding element include respective radially outwardly-projecting circumferential flanges, an annular recess is formed in the flange on the female grinding element and receives the flange on the sleeve and an inner face of the sleeve frictionally engages the second corrugated surface portions. 
   Preferably the apparatus further includes a body defining a condiment reservoir and driving means for rotating the shaft, wherein the shaft extends through the condiment reservoir and the male and female grinding elements are mounted at abase of the condiment reservoir. 
   This invention provides grinding apparatus which is effective and efficient in operational use, and which may be economically manufactured. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, wherein. 
       FIG. 1  is an exploded view of an embodiment of the condiment grinding apparatus of the invention; 
       FIG. 2  is a plan view of a female grinding element of the assembly of  FIG. 1 ; 
       FIG. 3  is a side elevation of the female grinding element of  FIG. 3 ; 
       FIG. 4  is a section along line AA of  FIG. 2 ; 
       FIG. 5  is a fragmentary section along line BB of  FIG. 4 ; 
       FIG. 6  is a plan view of a male grinding element of the assembly of  FIG. 1 ; 
       FIG. 7  is a side elevation of the male grinding element of  FIG. 6 ; 
       FIG. 8  is a bottom view showing the core assembled inside the male grinding element; 
       FIG. 9  is an enlargement of detail C of  FIG. 8 ; 
       FIG. 10  is a plan view of the assembly of  FIG. 1 ; 
       FIG. 11  is a cross section along line DD of  FIG. 10 , and 
       FIG. 12  is a schematic longitudinal section through a condiment grinder incorporating the assembly of  FIG. 1 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to the drawings,  FIG. 1  shows a grinding assembly  45  for a condiment grinding apparatus such as a pepper grinder. The grinding assembly  45  includes a composite female member  1  assembled from a female grinding element  2  and a sleeve  3 ; and a composite male member  4  assembled from a male grinding element  5  and a core  6 . The male and female members  1 ,  4  and their components are described with reference to their central axis  7 . As used herein, the term “axial” refers to a direction substantially parallel to the axis  7 . The term “radial” refers to a direction substantially orthogonal to the axis  7 . The term “circumferential” refers to the direction of a circular arc having a radius substantially orthogonal to the axis  7 . 
   As seen in  FIGS. 1 to 4 ,  10  and  11  the female grinding element  2  is pressed or punched from stainless steel sheet and has a generally tubular section  8  extending from an upper end  9  to a lower end  10 . Integral with the tubular section  8 , a flange  11  extending from the lower end  10  includes a radially-aligned portion  12  and a cylindrical lip  13  defining an annular recess  27 . Two diametrically opposing notches  20  are formed in the flange  11 . An aperture  14  extends axially through the grinding element  2  and defines an inner surface  15 . The outer end  10  is corrugated to provide helicoid first corrugated surface portions  16  in the inner surface  15 , and helicoid second corrugated surface portions  17  on an outer surface  18  of the female grinding element  2 . The upper end  9  includes eight circumferentially spaced punched teeth  19 , generally aligned axially and projecting from the inner surface  15 . Each tooth  19  is formed by punching, the material being sheared along a line  21  elongated in the axial direction to form first and second edges  22 ,  23 . The first edge  22  is displaced inwardly from the second edge  23 , both lying substantially in a common radial plane  25 . In this manner each tooth provides an opening  24 . A tapered face  26  of each tooth  19  extends substantially circumferentially from the first edge  22  to the inner surface  15 . The teeth  19  are aligned such that the tapered faces  26  extend in a common circumferential direction and the mouth of each opening  24  is facing in the same direction (e.g. in the counter clockwise direction as seen in  FIG. 5 ). 
   The sleeve  3  is shown in  FIGS. 1 ,  10  and  11  and is formed from polymer and has a cylindrical body  28  with an annular flange  29  at a lower end thereof in which two diametrically opposing notches  30  are formed. The sleeve  3  has an inner face  31  which sits adjacent the outer face  18  when the sleeve  3  is received in the female grinding element  2 . The flange  29  is received in the recess  27  and the notch pairs  20 ,  30  angularly aligned. The relatively soft sleeve  3  is deformed by contact with the second corrugated surface portions  17 , serving to restrict relative rotation between the sleeve  3  and grinding element  2 . 
     FIGS. 1 and 6  to  11  show the male grinding element  5  which is pressed or punched from stainless steel sheet and is tapered from a narrow upper end  32  to a broader axially opposing lower end  33 . The male grinding element  5  is corrugated to provide helicoid third corrugated surface portions  34  in an outer surface  35 , and helicoid fourth corrugated surface portions  36  on an inner surface  37 . An aperture  38  having a substantially square shaped cross-section extends axially through radially aligned face  39  at the upper end  32 . A corrugated annular edge  40  at the lower end  33  also lies in a radially-aligned plane. 
   The core  6  is formed of a polymer and, as illustrated in  FIGS. 8 and 9 , the core  6  is received in the male grinding element  5 , having an outer surface  41  in contact with the inner surface  37 , the complementary corrugations preventing relative rotation between the core  6  and the male grinding element  5 . The core  6  allows proper axial alignment of the composite male member  4  to be maintained and it also serves to reinforce the thin-walled male grinding element  5 , to distribute stresses in it. The core  6  may be adhesive bonded to the inner surface  37 . An aperture  42  having a square shaped cross-section extends axially through the core  6 , in alignment with the aperture  38 , both receiving a grinder shaft  43  having a square shaped cross-section and fixed to the end of the shaft  43 . 
   By way of example of the application of the grinding assembly  45 ,  FIG. 12  shows a condiment grinding apparatus  46  with a body  53  defining a condiment reservoir  49  at the base of which the grinding assembly  45  is mounted. The notch pairs  20 ,  30  are received in tabs (not shown) in the body  53 , to prevent rotation of the female member  1 . A rotary handle  48  is fixed to the top of the body  47  and is rotationally fast with the axially-extending shaft  43  with a square cross section and provides drive means for rotating the shaft  43 . The shaft  43  is received in the aligned apertures  38 ,  42  with the male member  4  received in female member  1 , a cavity  44  is provided for grinding condiment between the corrugated surface portions  16 ,  34  upon rotation of the handle  48 . An adjuster knob  50  is attached by a screw thread  51  to the top of the shaft  43 , such that rotation of the knob  50  moves the shaft  43  and the Male member  4  fixed to the end of the shaft  43  to adjust the size of the ground condiment in the known way. 
   Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.