Protective frame of a mask

A protective frame of a mask, said protective frame comprising:

• a first frame unit integrally formed as one piece, and including a first protective part for protecting a portion of a face of a user, and a first connecting part integrally connected to said first protective part;
• a second frame unit integrally formed as one piece, and including a second protective part for protecting another portion of the face of the user, and a second connecting part integrally connected to said second protective part;
• wherein said first connecting part of said first frame unit is connected to said second connecting part of said second frame unit, and said first frame unit and said second frame unit are connected together to constitute said protective frame;
• wherein said first frame unit includes two of said first connecting parts that are spaced apart from each other in a transverse direction transverse to a connecting direction between said first frame unit and said second frame unit, and said second frame unit includes two of said second connecting parts that are spaced apart from each other in the transverse direction;
• wherein said first frame unit and said second frame unit are made of a metallic material;
• wherein said first and second connecting parts are welded together;
• wherein each of said first connecting parts of said first frame unit includes a first female block formed with a first socket, and a first male block;
• wherein each of said second connecting parts of said second frame unit includes a second female block formed with a second socket into which said first male block is fittingly inserted, and a second male block fittingly inserted into said first socket in said first female block;
• wherein each of said first and second sockets has an opening facing one of a forward direction and a rearward direction, and is narrowed toward said opening;
• and
• wherein said first male block has a shape fittingly matching said second socket in said second female block, and said second male block has a shape fittingly matching said first socket in said first female block.