Hi,
The HP OfficeJet 4630 e-All-In-One Printer series is listed as supported in About AirPrint - Apple Support. I assume that you have checked all Wi-Fi settings, and that the printer and the iPad (and any computers) are connected to the same Wi-Fi router. This printer is 2.4 GHz only.
If necessary, and if supported by the router, use WPS.
http://h10032.www1.hp.com/ctg/Manual/c03909822.pdf (page 81)
Use AirPrint to print from your iPhone, iPad, or iPod touch - Apple Support
If there is a problem with AirPrint discovery for one or more devices, you may want to try the following full procedure (in the exact order):
Power off the Wi-Fi router, the printer, the iPad, and all other devices/computers. Wait two to three minutes. Power on the router. Wait two to three minutes. Power on the printer. Wait a minute or two. Power on the iPad. Finally, power on all other devices/computers.