He's probably drunk
Why does my father keep getting angry for no reason, or for some other problem that's not our fault, and yell at us, then say he's not angry?
Have you ever thought that maybe your Father is tired and stressed out? It's a tough time for Parents right now. He's probably just ridding himself of inner anger, but in the wrong direction. Good thing is, he knows it, that's why he say's he's not angry. Cut him some slack so he can relax. :)
Your Father sounds like he's stressed out to the max and its a law of Nature that we always take out our stress on those closest to us like your Father with you guys. Parenting is never easy and doesn't come with an instruction manual so combined with all the extra stress in life today and your Father is doing the best he can but the stresss is getting the best of him. Now you can help by not adding to his stress and helping around the house where you can and help him in any way you can.
Taking his anger out on you doesn't mean he doesn't love you anymore so don't ever think that. Its just extremely stressful in the world nowadays. Hope this makes sense and Merry Christmas